ANSYS Mechanical User's Guide PDF [PDF]

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ANSYS Mechanical User's Guide

ANSYS, Inc. Southpointe 275 Technology Drive Canonsburg, PA 15317 [email protected] http://www.ansys.com (T) 724-746-3304 (F) 724-514-9494

Release 15.0 November 2013 ANSYS, Inc. is certified to ISO 9001:2008.

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Table of Contents Overview .................................................................................................................................................. xxv Application Interface .................................................................................................................................. 1 Mechanical Application Window ............................................................................................................. 1 Windows Management ........................................................................................................................... 2 Main Windows ........................................................................................................................................ 3 Tree Outline ..................................................................................................................................... 3 Understanding the Tree Outline .................................................................................................. 4 Correlating Tree Outline Objects with Model Characteristics ........................................................ 6 Suppressing Objects ................................................................................................................... 8 Filtering the Tree ........................................................................................................................ 9 Details View .................................................................................................................................... 11 Parameterizing a Variable .......................................................................................................... 19 Geometry Window ......................................................................................................................... 20 Viewing the Legend .................................................................................................................. 21 Discrete Legends in the Mechanical Application .................................................................. 21 Print Preview .................................................................................................................................. 21 Report Preview ............................................................................................................................... 22 Publishing the Report ............................................................................................................... 23 Sending the Report .................................................................................................................. 23 Comparing Databases .............................................................................................................. 23 Customizing Report Content ..................................................................................................... 24 Contextual Windows ............................................................................................................................. 25 Selection Information Window ........................................................................................................ 25 Activating the Selection Information Window ............................................................................ 25 Understanding the Selection Modes ......................................................................................... 26 Using the Selection Information Window Toolbar ...................................................................... 33 Selecting, Exporting, and Sorting Data ....................................................................................... 36 Worksheet Window ........................................................................................................................ 38 Graph and Tabular Data Windows ................................................................................................... 39 Exporting Data ......................................................................................................................... 41 Messages Window .......................................................................................................................... 43 Graphics Annotation Window ......................................................................................................... 44 Section Planes Window ................................................................................................................... 44 Manage Views Window ................................................................................................................... 44 The Mechanical Wizard Window ...................................................................................................... 44 Main Menus ......................................................................................................................................... 44 File Menu ....................................................................................................................................... 44 Edit Menu ....................................................................................................................................... 45 View Menu ..................................................................................................................................... 45 Units Menu ..................................................................................................................................... 47 Tools Menu ..................................................................................................................................... 48 Help Menu ..................................................................................................................................... 48 Toolbars ............................................................................................................................................... 48 Standard Toolbar ............................................................................................................................ 49 Graphics Toolbar ............................................................................................................................. 50 Context Toolbar .............................................................................................................................. 53 Named Selection Toolbar ................................................................................................................ 69 Unit Conversion Toolbar .................................................................................................................. 69 Graphics Options Toolbar ................................................................................................................ 69 Edge Graphics Options ................................................................................................................... 71 Release 15.0 - © SAS IP, Inc. 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Mechanical User's Guide Tree Filter Toolbar ........................................................................................................................... 73 Interface Behavior Based on License Levels ........................................................................................... 73 Environment Filtering ........................................................................................................................... 74 Customizing the Mechanical Application ............................................................................................... 74 Specifying Options ......................................................................................................................... 74 Setting Variables ............................................................................................................................. 85 Using Macros .................................................................................................................................. 86 Working with Graphics .......................................................................................................................... 86 Selecting Geometry ........................................................................................................................ 87 Selecting Nodes ............................................................................................................................. 96 Creating a Coordinate System by Direct Node Selection .......................................................... 100 Specifying Named Selections by Direct Node Selection ........................................................... 101 Selecting Elements ....................................................................................................................... 101 Defining Direction ........................................................................................................................ 104 Using Viewports ........................................................................................................................... 106 Controlling Graphs and Charts ...................................................................................................... 106 Managing Graphical View Settings ................................................................................................ 107 Creating a View ....................................................................................................................... 107 Applying a View ...................................................................................................................... 108 Renaming a View .................................................................................................................... 108 Deleting a View ...................................................................................................................... 108 Replacing a Saved View ........................................................................................................... 108 Exporting a Saved View List ..................................................................................................... 108 Importing a Saved View List .................................................................................................... 109 Copying a View to Mechanical APDL ....................................................................................... 109 Creating Section Planes ................................................................................................................ 109 Adding a Section Plane ........................................................................................................... 111 Using Section Planes ............................................................................................................... 112 Modifying a Section Plane ....................................................................................................... 113 Deleting a Section Plane ......................................................................................................... 113 Controlling the Viewing Orientation .............................................................................................. 113 Viewing Annotations .................................................................................................................... 114 Specifying Annotation Preferences .......................................................................................... 119 Controlling Lighting ...................................................................................................................... 121 Inserting Comments, Images, and Figures ...................................................................................... 121 Mechanical Hotkeys ............................................................................................................................ 122 Wizards .............................................................................................................................................. 122 The Mechanical Wizard ................................................................................................................. 123 Steps for Using the Application .............................................................................................................. 125 Create Analysis System ....................................................................................................................... 125 Define Engineering Data ..................................................................................................................... 126 Attach Geometry ................................................................................................................................ 126 Define Part Behavior ........................................................................................................................... 129 Define Connections ............................................................................................................................ 132 Apply Mesh Controls and Preview Mesh .............................................................................................. 133 Establish Analysis Settings .................................................................................................................. 134 Define Initial Conditions ...................................................................................................................... 136 Applying Pre-Stress Effects for Implicit Analysis ................................................................................... 138 Applying Pre-Stress Effects for Explicit Analysis .................................................................................... 140 Apply Loads and Supports .................................................................................................................. 143 Solve .................................................................................................................................................. 145 Review Results .................................................................................................................................... 146

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Mechanical User's Guide Create Report (optional) ..................................................................................................................... 147 Analysis Types ......................................................................................................................................... 149 Design Assessment Analysis ................................................................................................................ 149 Electric Analysis .................................................................................................................................. 152 Explicit Dynamics Analysis .................................................................................................................. 155 Using Explicit Dynamics to Define Initial Conditions for Implicit Analysis ........................................ 176 Linear Dynamic Analysis Types ............................................................................................................ 179 Harmonic Response Analysis ......................................................................................................... 179 Harmonic Response (Full) Analysis Using Pre-Stressed Structural System ........................................ 188 Harmonic Response Analysis Using Linked Modal Analysis System ................................................. 189 Linear Buckling Analysis ................................................................................................................ 192 Modal Analysis ............................................................................................................................. 196 Random Vibration Analysis ........................................................................................................... 202 Response Spectrum Analysis ......................................................................................................... 207 Magnetostatic Analysis ....................................................................................................................... 212 Rigid Dynamics Analysis ..................................................................................................................... 216 Preparing a Rigid Dynamics Analysis ............................................................................................. 217 Command Reference for Rigid Dynamics Systems .......................................................................... 226 IronPython References ............................................................................................................ 226 The Rigid Dynamics Object Model ........................................................................................... 226 Rigid Dynamics Command Objects Library .............................................................................. 227 Command Use Examples ........................................................................................................ 241 Screw Joint ...................................................................................................................... 242 Constraint Equation ......................................................................................................... 242 Joint Condition: Initial Velocity .......................................................................................... 245 Joint Condition: Control Using Linear Feedback ................................................................. 245 Non-Linear Spring Damper ............................................................................................... 247 Spherical Stop .................................................................................................................. 248 Export of Joint Forces ........................................................................................................ 250 Breakable Joint ................................................................................................................ 252 Rigid Body Theory Guide ............................................................................................................... 252 Degrees of freedom ................................................................................................................ 253 Shape Functions ..................................................................................................................... 257 Equations of Motion ............................................................................................................... 259 Time Integration ..................................................................................................................... 263 Geometric Correction and Stabilization ................................................................................... 265 Contact and Stops .................................................................................................................. 266 References ............................................................................................................................. 272 Static Structural Analysis ..................................................................................................................... 272 Steady-State Thermal Analysis ............................................................................................................. 277 Thermal-Electric Analysis .................................................................................................................... 281 Transient Structural Analysis ............................................................................................................... 285 Transient Structural Analysis Using Linked Modal Analysis System ....................................................... 294 Transient Thermal Analysis .................................................................................................................. 297 Special Analysis Topics ........................................................................................................................ 301 Electromagnetics (EM) - Mechanical Data Transfer ......................................................................... 302 Importing Data into a Thermal or Structural (Static or Transient) Analysis ................................. 303 Importing Data into a Harmonic Analysis ................................................................................. 305 Exporting Results from a Thermal or Structural Analysis ........................................................... 308 External Data Import ..................................................................................................................... 310 External Data Export ..................................................................................................................... 317 Fluid-Structure Interaction (FSI) ..................................................................................................... 317 Release 15.0 - © SAS IP, Inc. 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Mechanical User's Guide One-Way Transfer FSI .............................................................................................................. 318 Two-Way Transfer FSI .............................................................................................................. 318 Using Imported Loads for One-Way FSI .................................................................................... 319 Face Forces at Fluid-Structure Interface ............................................................................. 321 Face Temperatures and Convections at Fluid-Structure Interface ........................................ 321 Volumetric Temperature Transfer ....................................................................................... 322 CFD Results Mapping ........................................................................................................ 322 Icepak to Mechanical Data Transfer ............................................................................................... 322 Mechanical-Electronics Interaction (Mechatronics) Data Transfer .................................................... 324 Overall Workflow for Mechatronics Analysis ............................................................................. 324 Set up the Mechanical Application for Export to Simplorer ....................................................... 325 Polyflow to Mechanical Data Transfer ............................................................................................ 325 Simplorer/Rigid Dynamics Co-Simulation ..................................................................................... 327 Simplorer Pins ........................................................................................................................ 329 Static Analysis From Rigid Dynamics Analysis ................................................................................ 330 Submodeling ................................................................................................................................ 331 Understanding Submodeling .................................................................................................. 332 Shell-to-Solid Submodels .................................................................................................. 333 Nonlinear Submodeling .................................................................................................... 334 Structural Submodeling Workflow ........................................................................................... 334 Thermal Submodeling Workflow ............................................................................................. 339 System Coupling .......................................................................................................................... 342 Supported Capabilities and Limitations ................................................................................... 343 Variables Available for System Coupling .................................................................................. 344 System Coupling Related Settings in Mechanical ..................................................................... 345 Fluid-Structure Interaction (FSI) - One-Way Transfers Using System Coupling ............................ 347 Thermal-Fluid-Structural Analyses using System Coupling ....................................................... 348 Restarting Structural Mechanical Analyses as Part of System Coupling ..................................... 350 Generating Mechanical Restart Files .................................................................................. 350 Specifying a Restart Point in Mechanical ............................................................................ 351 Making Changes in Mechanical Before Restarting .............................................................. 351 Recovering the Mechanical Restart Point after a Workbench Crash ..................................... 351 Running Mechanical as a System Coupling Participant from the Command Line ....................... 352 Troubleshooting Two-Way Coupling Analysis Problems ........................................................... 353 Product Licensing Considerations when using System Coupling .............................................. 353 Thermal-Stress Analysis ................................................................................................................. 354 One-way Acoustic Coupling Analysis ............................................................................................. 358 Rotordynamics Analysis ................................................................................................................ 360 Fracture Analysis ........................................................................................................................... 361 Fracture Analysis Workflows .................................................................................................... 361 Limitations of Fracture Analysis ............................................................................................... 363 Multi-Point Constraint (MPC) Contact for Fracture .................................................................... 363 Composite Analysis ....................................................................................................................... 364 Shell Modeling Workflow ........................................................................................................ 364 Solid Modeling Workflow ........................................................................................................ 366 Specifying Geometry .............................................................................................................................. 371 Geometry Basics ................................................................................................................................. 371 Multibody Behavior ...................................................................................................................... 372 Working with Parts ....................................................................................................................... 372 Associativity ................................................................................................................................. 372 Integration Schemes ..................................................................................................................... 373 Color Coding of Parts .................................................................................................................... 373

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Mechanical User's Guide Working with Bodies ..................................................................................................................... 374 Hide or Suppress Bodies ............................................................................................................... 375 Hide or Show Faces ....................................................................................................................... 375 Assumptions and Restrictions for Assemblies, Parts, and Bodies ..................................................... 376 Solid Bodies ........................................................................................................................................ 376 Surface Bodies .................................................................................................................................... 376 Assemblies of Surface Bodies ........................................................................................................ 376 Thickness Mode ............................................................................................................................ 377 Importing Surface Body Models .................................................................................................... 377 Importing Surface Body Thickness ................................................................................................ 378 Surface Body Shell Offsets ............................................................................................................. 378 Specifying Surface Body Thickness ................................................................................................ 380 Specifying Surface Body Layered Sections ..................................................................................... 383 Defining and Applying a Layered Section ................................................................................ 383 Viewing Individual Layers ........................................................................................................ 384 Layered Section Properties ...................................................................................................... 385 Notes on Layered Section Behavior ......................................................................................... 385 Faces With Multiple Thicknesses and Layers Specified .................................................................... 386 Line Bodies ......................................................................................................................................... 387 Mesh-Based Geometry ........................................................................................................................ 388 CDB Import Element Types ............................................................................................................ 397 Assembling Mechanical Models .......................................................................................................... 398 Rigid Bodies ....................................................................................................................................... 401 2D Analyses ........................................................................................................................................ 402 Using Generalized Plane Strain ...................................................................................................... 404 Symmetry ........................................................................................................................................... 405 Types of Regions ........................................................................................................................... 406 Symmetry Region ................................................................................................................... 407 Explicit Dynamics Symmetry ............................................................................................. 409 General Symmetry ...................................................................................................... 410 Global Symmetry Planes ............................................................................................. 410 Periodic Region ...................................................................................................................... 411 Electromagnetic Periodic Symmetry .................................................................................. 411 Periodicity Example .................................................................................................... 412 Cyclic Region .......................................................................................................................... 414 Cyclic Symmetry in a Static Structural Analysis ................................................................... 416 Applying Loads and Supports for Cyclic Symmetry in a Static Structural Analysis .......... 416 Reviewing Results for Cyclic Symmetry in a Static Structural Analysis ........................... 417 Cyclic Symmetry in a Modal Analysis ................................................................................. 418 Applying Loads and Supports for Cyclic Symmetry in a Modal Analysis ........................ 418 Analysis Settings for Cyclic Symmetry in a Modal Analysis ............................................ 419 Reviewing Results for Cyclic Symmetry in a Modal Analysis .......................................... 419 Cyclic Symmetry in a Thermal Analysis ............................................................................... 425 Applying Loads for Cyclic Symmetry in a Thermal Analysis ........................................... 425 Reviewing Results for Cyclic Symmetry in a Thermal Analysis ....................................... 425 Symmetry Defined in DesignModeler ............................................................................................ 425 Symmetry in the Mechanical Application ...................................................................................... 426 Named Selections ............................................................................................................................... 429 Defining Named Selections ........................................................................................................... 432 Specifying Named Selections by Geometry Type ..................................................................... 433 Specifying Named Selections using Worksheet Criteria ............................................................ 434 Promoting Scoped Objects to a Named Selection .......................................................................... 441 Release 15.0 - © SAS IP, Inc. 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Mechanical User's Guide Displaying Named Selections ........................................................................................................ 442 Using Named Selections ............................................................................................................... 446 Using Named Selections via the Toolbar .................................................................................. 446 Scoping Analysis Objects to Named Selections ........................................................................ 448 Including Named Selections in Program Controlled Inflation .................................................... 448 Importing Named Selections ................................................................................................... 448 Exporting Named Selections ................................................................................................... 449 Displaying Interior Mesh Faces ...................................................................................................... 449 Converting Named Selection Groups to Mechanical APDL Application Components ...................... 450 Mesh Numbering ................................................................................................................................ 451 Path (Construction Geometry) ............................................................................................................. 453 Surface (Construction Geometry) ........................................................................................................ 459 Remote Point ...................................................................................................................................... 460 Specify a Remote Point ................................................................................................................. 461 Geometry Behaviors and Support Specifications ........................................................................... 464 Remote Point Features .................................................................................................................. 466 Point Mass .......................................................................................................................................... 468 Thermal Point Mass ............................................................................................................................. 469 Cracks ................................................................................................................................................ 471 Defining a Pre-Meshed Crack ........................................................................................................ 473 Interface Delamination and Contact Debonding .................................................................................. 474 Interface Delamination Application ............................................................................................... 475 Contact Debonding Application .................................................................................................... 478 Interface Delamination and ANSYS Composite PrepPost (ACP) ....................................................... 479 Gaskets .............................................................................................................................................. 480 Gasket Bodies ............................................................................................................................... 481 Gasket Mesh Control ..................................................................................................................... 481 Gasket Results .............................................................................................................................. 482 Setting Up Coordinate Systems .............................................................................................................. 483 Creating Coordinate Systems .............................................................................................................. 483 Initial Creation and Definition ....................................................................................................... 483 Establishing Origin for Associative and Non-Associative Coordinate Systems .................................. 484 Setting Principal Axis and Orientation ........................................................................................... 486 Using Transformations .................................................................................................................. 487 Creating a Coordinate System Based on a Surface Normal .............................................................. 487 Importing Coordinate Systems ............................................................................................................ 488 Applying Coordinate Systems as Reference Locations .......................................................................... 488 Using Coordinate Systems to Specify Joint Locations ........................................................................... 489 Creating Section Planes ...................................................................................................................... 489 Create Construction Surface ................................................................................................................ 491 Transferring Coordinate Systems to the Mechanical APDL Application ................................................. 492 Setting Connections ............................................................................................................................... 493 Connections Folder ............................................................................................................................. 493 Connections Worksheet ...................................................................................................................... 494 Connection Group Folder .................................................................................................................... 497 Common Connections Folder Operations for Auto Generated Connections .......................................... 501 Contact .............................................................................................................................................. 503 Contact Overview ......................................................................................................................... 503 Contact Formulation Theory ......................................................................................................... 504 Contact Settings ........................................................................................................................... 506 Scope Settings ........................................................................................................................ 507 Definition Settings .................................................................................................................. 510

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Mechanical User's Guide Advanced Settings .................................................................................................................. 515 Geometric Modification .......................................................................................................... 525 Supported Contact Types .............................................................................................................. 528 Setting Contact Conditions Manually ............................................................................................ 529 Contact Ease of Use Features ......................................................................................................... 530 Controlling Transparency for Contact Regions ......................................................................... 530 Displaying Contact Bodies with Different Colors ...................................................................... 530 Displaying Contact Bodies in Separate Windows ...................................................................... 531 Hiding Bodies Not Scoped to a Contact Region ........................................................................ 532 Renaming Contact Regions Based on Geometry Names ........................................................... 532 Identifying Contact Regions for a Body .................................................................................... 533 Create Contact Debonding ..................................................................................................... 533 Flipping Contact and Target Scope Settings ............................................................................. 533 Merging Contact Regions That Share Geometry ....................................................................... 534 Saving or Loading Contact Region Settings ............................................................................. 534 Resetting Contact Regions to Default Settings ......................................................................... 535 Locating Bodies Without Contact ............................................................................................ 535 Locating Parts Without Contact ............................................................................................... 535 Contact in Rigid Dynamics ............................................................................................................ 535 Best Practices for Specifying Contact Conditions ............................................................................ 538 Joints ................................................................................................................................................. 542 Joint Characteristics ...................................................................................................................... 542 Joint Types ................................................................................................................................... 545 Joint Properties ............................................................................................................................ 553 Joint Stiffness ............................................................................................................................... 562 Manual Joint Creation ................................................................................................................... 564 Example: Assembling Joints .......................................................................................................... 566 Example: Configuring Joints .......................................................................................................... 576 Automatic Joint Creation .............................................................................................................. 589 Joint Stops and Locks .................................................................................................................... 590 Ease of Use Features ..................................................................................................................... 594 Detecting Overconstrained Conditions .......................................................................................... 597 Mesh Connection ............................................................................................................................... 598 Springs ............................................................................................................................................... 606 Beam Connections .............................................................................................................................. 614 Spot Welds ......................................................................................................................................... 616 End Releases ....................................................................................................................................... 619 Body Interactions in Explicit Dynamics Analyses .................................................................................. 619 Properties for Body Interactions Folder .......................................................................................... 621 Contact Detection .................................................................................................................. 621 Formulation ............................................................................................................................ 623 Shell Thickness Factor ............................................................................................................. 624 Body Self Contact ................................................................................................................... 625 Element Self Contact ............................................................................................................... 625 Tolerance ................................................................................................................................ 625 Pinball Factor .......................................................................................................................... 626 Time Step Safety Factor ........................................................................................................... 626 Limiting Time Step Velocity ..................................................................................................... 626 Edge on Edge Contact ............................................................................................................ 626 Interaction Type Properties for Body Interaction Object ................................................................. 627 Frictionless Type ..................................................................................................................... 627 Frictional Type ........................................................................................................................ 627 Release 15.0 - © SAS IP, Inc. 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Mechanical User's Guide Bonded Type .......................................................................................................................... 628 Reinforcement Type ................................................................................................................ 630 Identifying Body Interactions Regions for a Body ........................................................................... 632 Bearings ............................................................................................................................................. 632 Configuring Analysis Settings ................................................................................................................ 635 Analysis Settings for Most Analysis Types ............................................................................................. 635 Step Controls ................................................................................................................................ 635 Solver Controls ............................................................................................................................. 639 Restart Analysis ............................................................................................................................ 644 Restart Controls ............................................................................................................................ 644 Creep Controls .............................................................................................................................. 646 Cyclic Controls .............................................................................................................................. 646 Radiosity Controls ......................................................................................................................... 647 Options for Analyses ..................................................................................................................... 648 Damping Controls ........................................................................................................................ 653 Nonlinear Controls ........................................................................................................................ 655 Output Controls ............................................................................................................................ 658 Analysis Data Management ........................................................................................................... 664 Rotordynamics Controls ................................................................................................................ 666 Visibility ....................................................................................................................................... 666 Steps and Step Controls for Static and Transient Analyses .................................................................... 666 Role of Time in Tracking ................................................................................................................ 667 Steps, Substeps, and Equilibrium Iterations .................................................................................... 667 Automatic Time Stepping ............................................................................................................. 668 Guidelines for Integration Step Size ............................................................................................... 669 Analysis Settings for Explicit Dynamics Analyses .................................................................................. 670 Explicit Dynamics Step Controls .................................................................................................... 671 Explicit Dynamics Solver Controls .................................................................................................. 675 Explicit Dynamics Euler Domain Controls ...................................................................................... 678 Explicit Dynamics Damping Controls ............................................................................................. 680 Explicit Dynamics Erosion Controls ................................................................................................ 681 Explicit Dynamics Output Controls ................................................................................................ 682 Explicit Dynamics Data Management Settings ............................................................................... 685 Recommendations for Analysis Settings in Explicit Dynamics ......................................................... 685 Explicit Dynamics Analysis Settings Notes ..................................................................................... 689 Setting Up Boundary Conditions ............................................................................................................ 691 Boundary Condition Scoping Method ................................................................................................. 691 Types of Boundary Conditions ............................................................................................................. 694 Inertial Type Boundary Conditions ................................................................................................. 694 Acceleration ........................................................................................................................... 694 Standard Earth Gravity ............................................................................................................ 698 Rotational Velocity .................................................................................................................. 700 Load Type Boundary Conditions .................................................................................................... 703 Pressure ................................................................................................................................. 705 Pipe Pressure .......................................................................................................................... 708 Pipe Temperature ................................................................................................................... 710 Hydrostatic Pressure ............................................................................................................... 712 Force ...................................................................................................................................... 716 Remote Force ......................................................................................................................... 719 Bearing Load .......................................................................................................................... 723 Bolt Pretension ....................................................................................................................... 727 Moment ................................................................................................................................. 731

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Mechanical User's Guide Generalized Plane Strain ......................................................................................................... 734 Line Pressure .......................................................................................................................... 737 PSD Base Excitation ................................................................................................................ 740 RS Base Excitation ................................................................................................................... 741 Joint Load ............................................................................................................................... 742 Thermal Condition .................................................................................................................. 744 Temperature ........................................................................................................................... 747 Convection ............................................................................................................................. 749 Radiation ................................................................................................................................ 753 Heat Flow ............................................................................................................................... 757 Heat Flux ................................................................................................................................ 759 Internal Heat Generation ......................................................................................................... 762 Voltage ................................................................................................................................... 764 Current ................................................................................................................................... 766 Electromagnetic Boundary Conditions and Excitations ............................................................ 769 Magnetic Flux Boundary Conditions .................................................................................. 769 Conductor ........................................................................................................................ 771 Solid Source Conductor Body ...................................................................................... 771 Voltage Excitation for Solid Source Conductors ............................................................ 773 Current Excitation for Solid Source Conductors ............................................................ 774 Stranded Source Conductor Body ............................................................................... 775 Current Excitation for Stranded Source Conductors ..................................................... 777 Motion Load ........................................................................................................................... 779 Fluid Solid Interface ................................................................................................................ 782 Detonation Point .................................................................................................................... 784 Support Type Boundary Conditions ............................................................................................... 788 Fixed Supports ....................................................................................................................... 789 Displacements ........................................................................................................................ 791 Remote Displacement ............................................................................................................. 794 Velocity .................................................................................................................................. 798 Impedance Boundary ............................................................................................................. 800 Frictionless Face ...................................................................................................................... 803 Compression Only Support ..................................................................................................... 805 Cylindrical Support ................................................................................................................. 808 Simply Supported ................................................................................................................... 809 Fixed Rotation ........................................................................................................................ 811 Elastic Support ....................................................................................................................... 813 Conditions Type Boundary Conditions ........................................................................................... 815 Coupling ................................................................................................................................ 815 Constraint Equation ................................................................................................................ 817 Pipe Idealization ..................................................................................................................... 819 Direct FE Type Boundary Conditions .............................................................................................. 822 Nodal Orientation ................................................................................................................... 822 Nodal Force ............................................................................................................................ 823 Nodal Pressure ........................................................................................................................ 825 Nodal Displacement ............................................................................................................... 827 Nodal Rotation ....................................................................................................................... 829 EM (Electro-Mechanical) Transducer ........................................................................................ 831 Remote Boundary Conditions ....................................................................................................... 833 Imported Boundary Conditions ..................................................................................................... 834 Imported Body Force Density .................................................................................................. 838 Imported Body Temperature ................................................................................................... 839 Release 15.0 - © SAS IP, Inc. 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Mechanical User's Guide Imported Convection Coefficient ............................................................................................ 840 Imported Displacement .......................................................................................................... 840 Imported Force ....................................................................................................................... 841 Imported Heat Flux ................................................................................................................. 841 Imported Heat Generation ...................................................................................................... 841 Imported Initial Strain ............................................................................................................. 842 Imported Initial Stress ............................................................................................................. 843 Recommendations and Guidelines for Mapping of Initial Stress and Strain Data ................. 844 Imported Pressure .................................................................................................................. 845 Imported Remote Loads ......................................................................................................... 846 Imported Surface Force Density .............................................................................................. 846 Imported Temperature ............................................................................................................ 846 Imported Velocity ................................................................................................................... 847 Spatial Varying Loads and Displacements ............................................................................................ 847 Defining Boundary Condition Magnitude ............................................................................................ 848 Using Results .......................................................................................................................................... 857 Introduction to the Use of Results ....................................................................................................... 857 Result Definitions ............................................................................................................................... 858 Applying Results Based on Geometry ............................................................................................ 858 Scoping Results ............................................................................................................................ 861 Solution Coordinate System .......................................................................................................... 863 Material Properties Used in Postprocessing ................................................................................... 865 Clearing Results Data .................................................................................................................... 865 Averaged vs. Unaveraged Contour Results ..................................................................................... 866 Peak Composite Results ................................................................................................................ 874 Layered and Surface Body Results ................................................................................................. 875 Unconverged Results .................................................................................................................... 876 Handling of Degenerate Elements ................................................................................................. 877 Structural Results ................................................................................................................................ 877 Deformation ................................................................................................................................. 879 Stress and Strain ........................................................................................................................... 882 Equivalent (von Mises) ............................................................................................................ 883 Maximum, Middle, and Minimum Principal .............................................................................. 883 Maximum Shear ..................................................................................................................... 884 Intensity ................................................................................................................................. 884 Vector Principals ..................................................................................................................... 885 Error (Structural) ..................................................................................................................... 885 Thermal Strain ........................................................................................................................ 886 Equivalent Plastic Strain .......................................................................................................... 887 Equivalent Creep Strain ........................................................................................................... 888 Equivalent Total Strain ............................................................................................................ 888 Membrane Stress .................................................................................................................... 888 Bending Stress ........................................................................................................................ 889 Stabilization Energy ...................................................................................................................... 889 Strain Energy ................................................................................................................................ 890 Linearized Stress ........................................................................................................................... 890 Damage Results ............................................................................................................................ 892 Contact Results ............................................................................................................................. 895 Frequency Response and Phase Response ..................................................................................... 898 Stress Tools ................................................................................................................................... 904 Maximum Equivalent Stress Safety Tool .................................................................................. 905 Maximum Shear Stress Safety Tool .......................................................................................... 907

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Mechanical User's Guide Mohr-Coulomb Stress Safety Tool ............................................................................................ 908 Maximum Tensile Stress Safety Tool ......................................................................................... 910 Fatigue (Fatigue Tool) .................................................................................................................... 912 Fracture Results ............................................................................................................................ 912 Fracture Tool ........................................................................................................................... 915 Defining a Fracture Result ....................................................................................................... 915 Contact Tool ................................................................................................................................. 916 Contact Tool Initial Information ............................................................................................... 920 Beam Tool ..................................................................................................................................... 922 Beam Results ................................................................................................................................ 923 Shear-Moment Diagram .......................................................................................................... 924 Structural Probes .......................................................................................................................... 926 Energy (Transient Structural and Rigid Dynamics Analyses) ...................................................... 936 Reactions: Forces and Moments .............................................................................................. 937 Joint Probes ............................................................................................................................ 944 Response PSD Probe ............................................................................................................... 946 Spring Probes ......................................................................................................................... 947 Bearing Probes ....................................................................................................................... 947 Beam Probes .......................................................................................................................... 948 Bolt Pretension Probes ............................................................................................................ 948 Generalized Plain Strain Probes ............................................................................................... 948 Gasket Results .............................................................................................................................. 948 Campbell Diagram Chart Results ................................................................................................... 949 Thermal Results .................................................................................................................................. 952 Temperature ................................................................................................................................. 952 Heat Flux ...................................................................................................................................... 952 Heat Reaction ............................................................................................................................... 953 Error (Thermal) ............................................................................................................................. 953 Thermal Probes ............................................................................................................................. 953 Magnetostatic Results ......................................................................................................................... 955 Electric Potential ........................................................................................................................... 955 Total Magnetic Flux Density .......................................................................................................... 955 Directional Magnetic Flux Density ................................................................................................. 955 Total Magnetic Field Intensity ........................................................................................................ 956 Directional Magnetic Field Intensity .............................................................................................. 956 Total Force .................................................................................................................................... 956 Directional Force .......................................................................................................................... 956 Current Density ............................................................................................................................ 956 Inductance ................................................................................................................................... 956 Flux Linkage ................................................................................................................................. 957 Error (Magnetic) ............................................................................................................................ 958 Magnetostatic Probes ................................................................................................................... 958 Electric Results .................................................................................................................................... 960 Electric Probes .............................................................................................................................. 961 Fatigue Results ................................................................................................................................... 961 Fatigue Material Properties ........................................................................................................... 962 Fatigue Analysis and Loading Options ........................................................................................... 963 Reviewing Fatigue Results ............................................................................................................. 966 User Defined Results ........................................................................................................................... 970 Overview ...................................................................................................................................... 970 Characteristics .............................................................................................................................. 971 Application ................................................................................................................................... 972 Release 15.0 - © SAS IP, Inc. 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Mechanical User's Guide Node-Based Scoping .................................................................................................................... 973 User Defined Result Expressions .................................................................................................... 974 User Defined Result Identifier ........................................................................................................ 977 Unit Description ........................................................................................................................... 978 User Defined Results for the Mechanical APDL Solver .................................................................... 979 User Defined Results for Explicit Dynamics Analyses ...................................................................... 983 Result Outputs .................................................................................................................................... 988 Chart and Table ............................................................................................................................ 988 Contour Results ............................................................................................................................ 991 Coordinate Systems Results .......................................................................................................... 991 Nodal Coordinate Systems Results ........................................................................................... 991 Elemental Coordinate Systems Results .................................................................................... 992 Rotational Order of Coordinate System Results ........................................................................ 993 Eroded Nodes in Explicit Dynamics Analyses ................................................................................. 993 Euler Domain in Explicit Dynamics Analyses .................................................................................. 995 Path Results .................................................................................................................................. 996 Probes ........................................................................................................................................ 1001 Overview and Probe Types .................................................................................................... 1001 Probe Details View ................................................................................................................ 1003 Surface Results ........................................................................................................................... 1007 Vector Plots ................................................................................................................................ 1010 Result Summary Worksheet ......................................................................................................... 1010 Result Utilities ................................................................................................................................... 1011 Adaptive Convergence ................................................................................................................ 1011 Animation .................................................................................................................................. 1011 Capped Isosurfaces ..................................................................................................................... 1014 Dynamic Legend ......................................................................................................................... 1015 Exporting Results ........................................................................................................................ 1016 Generating Reports ..................................................................................................................... 1017 Renaming Results Based on Definition ........................................................................................ 1017 Results Legend ........................................................................................................................... 1017 Results Toolbar ........................................................................................................................... 1019 Solution Combinations ............................................................................................................... 1019 Understanding Solving ......................................................................................................................... 1023 Solve Modes and Recommended Usage ............................................................................................ 1025 Using Solve Process Settings ............................................................................................................. 1027 Solution Restarts ............................................................................................................................... 1032 Solving Scenarios .............................................................................................................................. 1040 Solution Information Object .............................................................................................................. 1042 Postprocessing During Solve ............................................................................................................. 1048 Result Trackers .................................................................................................................................. 1049 Structural Result Trackers ............................................................................................................ 1051 Thermal Result Trackers ............................................................................................................... 1053 Explicit Dynamics Result Trackers ................................................................................................ 1054 Point Scoped Result Trackers for Explicit Dynamics ................................................................ 1054 Body Scoped Result Trackers for Explicit Dynamics ................................................................ 1059 Force Reaction Result Trackers for Explicit Dynamics .............................................................. 1063 Spring Result Trackers for Explicit Dynamics .......................................................................... 1064 Viewing and Filtering Result Tracker Graphs for Explicit Dynamics .......................................... 1064 Adaptive Convergence ...................................................................................................................... 1065 File Management in the Mechanical Application ................................................................................ 1070 Solving Units .................................................................................................................................... 1071

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Mechanical User's Guide Saving your Results in the Mechanical Application ............................................................................. 1132 Writing and Reading the Mechanical APDL Application Files .............................................................. 1133 Converting Boundary Conditions to Nodal DOF Constraints (Mechanical APDL Solver) ....................... 1135 Resolving Thermal Boundary Condition Conflicts ............................................................................... 1136 Resume Capability for Explicit Dynamics Analyses ............................................................................. 1136 Solving a Fracture Analysis ................................................................................................................ 1137 Commands Objects ............................................................................................................................... 1141 Commands Object Features .............................................................................................................. 1141 Using Commands Objects with the MAPDL Solver ............................................................................. 1145 Using Commands Objects with the Rigid Dynamics Solver ................................................................ 1149 Setting Parameters ............................................................................................................................... 1151 Specifying Parameters ....................................................................................................................... 1151 CAD Parameters ................................................................................................................................ 1153 Using Design Assessment ..................................................................................................................... 1157 Predefined Assessment Types ............................................................................................................ 1159 Modifying the Predefined Assessment Types Menu ...................................................................... 1160 Using Advanced Combination Options with Design Assessment .................................................. 1160 Introduction ......................................................................................................................... 1161 Defining Results .................................................................................................................... 1161 Using BEAMST and FATJACK with Design Assessment .................................................................. 1163 Using BEAMST with the Design Assessment System ..................................................................... 1163 Introduction ......................................................................................................................... 1163 Information for Existing ASAS Users ....................................................................................... 1164 Attribute Group Types ........................................................................................................... 1166 Code of Practise Selection ............................................................................................... 1167 General Text .................................................................................................................... 1168 Geometry Definition ....................................................................................................... 1168 Load Dependant Factors ................................................................................................. 1169 Material Definition .......................................................................................................... 1170 Ocean Environment ........................................................................................................ 1171 Available Results ................................................................................................................... 1171 AISC LRFD Results ........................................................................................................... 1171 AISC WSD Results ............................................................................................................ 1172 API LRFD Results ............................................................................................................. 1173 API WSD Results .............................................................................................................. 1176 BS5950 Results ................................................................................................................ 1182 DS449 High Results ......................................................................................................... 1182 DS449 Normal Results ..................................................................................................... 1185 ISO Results ...................................................................................................................... 1186 NORSOK Results .............................................................................................................. 1189 NPD Results .................................................................................................................... 1192 Using FATJACK with the Design Assessment System .................................................................... 1195 Introduction ......................................................................................................................... 1195 Information for Existing ASAS Users ....................................................................................... 1196 Solution Selection Customization .......................................................................................... 1197 Attribute Group Types ........................................................................................................... 1198 Analysis Type Selection ................................................................................................... 1198 General Text .................................................................................................................... 1199 Geometry Definition ....................................................................................................... 1199 Joint Inspection Points ................................................................................................... 1200 SCF Definitions ............................................................................................................... 1200 Material Definition .......................................................................................................... 1201 Release 15.0 - © SAS IP, Inc. 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Mechanical User's Guide Ocean Environment ........................................................................................................ 1202 Available Results ................................................................................................................... 1202 Damage Values ............................................................................................................... 1203 Fatigue Assessment ........................................................................................................ 1204 SCF Values ...................................................................................................................... 1204 Stress Histogram Results ................................................................................................. 1204 Stress Range Results ....................................................................................................... 1205 Changing the Assessment Type or XML Definition File Contents ......................................................... 1206 Solution Selection ............................................................................................................................. 1207 The Solution Selection Table ....................................................................................................... 1207 Results Availability ...................................................................................................................... 1208 Solution Combination Behavior ................................................................................................... 1209 Using the Attribute Group Object ...................................................................................................... 1211 Developing and Debugging Design Assessment Scripts .................................................................... 1212 Using the DA Result Object ............................................................................................................... 1213 The Design Assessment XML Definition File ....................................................................................... 1214 Attributes Format ....................................................................................................................... 1215 Attribute Groups Format ............................................................................................................. 1218 Script Format .............................................................................................................................. 1219 Results Format ............................................................................................................................ 1222 Design Assessment API Reference ..................................................................................................... 1225 DesignAssessment class .............................................................................................................. 1232 Example Usage ..................................................................................................................... 1233 Typical Evaluate (or Solve) Script Output ................................................................................ 1234 Helper class ................................................................................................................................ 1234 Example Usage ..................................................................................................................... 1235 Typical Evaluate (or Solve) Script Output ................................................................................ 1235 Typical Solver Output ............................................................................................................ 1235 MeshData class ........................................................................................................................... 1236 Example Usage ..................................................................................................................... 1236 Typical Evaluate (or Solve) Script Output ................................................................................ 1237 DAElement class ......................................................................................................................... 1237 Example Usage ..................................................................................................................... 1239 Typical Evaluate (or Solve) Script Output ................................................................................ 1239 DANode class ............................................................................................................................. 1239 Example Usage ..................................................................................................................... 1240 Typical Evaluate (or Solve) Script Output ................................................................................ 1240 SectionData class ........................................................................................................................ 1240 Example Usage ..................................................................................................................... 1241 Typical Evaluate (or Solve) Script Output ................................................................................ 1241 AttributeGroup class ................................................................................................................... 1242 Example Usage ..................................................................................................................... 1242 Typical Evaluate (or Solve) Script Output ................................................................................ 1242 Attribute class ............................................................................................................................. 1243 Example Usage ..................................................................................................................... 1243 Typical Evaluate (or Solve) Script Output ................................................................................ 1244 SolutionSelection class ............................................................................................................... 1244 Example Usage ..................................................................................................................... 1244 Typical Evaluate (or Solve) Script Output ................................................................................ 1244 Solution class .............................................................................................................................. 1245 Example Usage ..................................................................................................................... 1248 Typical Evaluate (or Solve) Script Output ................................................................................ 1249

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Mechanical User's Guide SolutionResult class .................................................................................................................... 1249 Example Usage ..................................................................................................................... 1254 Typical Evaluate (or Solve) Script Output ................................................................................ 1254 DAResult class ............................................................................................................................ 1255 Example Usage ..................................................................................................................... 1256 Typical Evaluate (or Solve) Script Output ................................................................................ 1257 DAResultSet class ........................................................................................................................ 1257 Example Usage ..................................................................................................................... 1258 Typical Evaluate (or Solve) Script Output ................................................................................ 1259 Examples of Design Assessment Usage .............................................................................................. 1259 Using Design Assessment to Obtain Results from Mechanical APDL ............................................. 1260 Creating the XML Definition File ............................................................................................ 1260 Creating the Script to be Run on Solve, MAPDL_S.py ........................................................... 1263 Creating the Script to be Run on Evaluate All Results, MAPDL_E.py ...................................... 1264 Expanding the Example ........................................................................................................ 1265 Using Design Assessment to Calculate Complex Results, such as Those Required by ASME ............ 1266 Creating the XML Definition File ............................................................................................ 1266 Creating the Script to be Run on Evaluate .............................................................................. 1268 EvaluateAllResults ........................................................................................................... 1268 EvaluateDamage ............................................................................................................. 1268 EvaluateCulmativeDamage ............................................................................................. 1269 Plot ................................................................................................................................ 1269 Using Design Assessment to Perform Further Results Analysis for an Explicit Dynamics Analysis .... 1270 Creating the XML Definition File ............................................................................................ 1270 Creating the Script to be Run on Evaluate .............................................................................. 1272 Expanding the Example ........................................................................................................ 1273 Using Design Assessment to Obtain Composite Results Using Mechanical APDL .......................... 1273 Creating the XML Definition File ............................................................................................ 1275 Creating the Script to be Run on Solve, SolveFailure.py ................................................ 1277 Creating the Script to be Run on Evaluate All Results, EvaluateFailure.py ..................... 1277 Using a Dictionary to Avoid a Long if/elif/else Statement. ................................................. 1277 Writing the MADPL .inp File from Within Design Assessment ........................................ 1278 Running Mechanical APDL Multiple Times ....................................................................... 1278 Expanding the Example ........................................................................................................ 1279 Using Design Assessment to Access and Present Multiple Step Results ......................................... 1279 Creating the XML Definition File ............................................................................................ 1279 Creating the Script to be Run on Evaluate .............................................................................. 1280 Using Design Assessment to Perform an Explicit-to-Implicit Sequential Analysis ........................... 1281 Creating the XML Definition File ............................................................................................ 1281 Creating the Solve Script ....................................................................................................... 1281 Productivity Tools ................................................................................................................................. 1287 Generating Multiple Objects from a Template Object ......................................................................... 1287 Tagging Objects ................................................................................................................................ 1292 Creating Tags .............................................................................................................................. 1292 Applying Tags to Objects ............................................................................................................. 1292 Deleting a Tag ............................................................................................................................. 1293 Renaming a Tag .......................................................................................................................... 1293 Highlighting Tagged Tree Objects ................................................................................................ 1293 Objects Reference ................................................................................................................................. 1295 Alert ................................................................................................................................................. 1297 Analysis Settings ............................................................................................................................... 1298 Angular Velocity ................................................................................................................................ 1299 Release 15.0 - © SAS IP, Inc. 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Mechanical User's Guide Beam ................................................................................................................................................ 1300 Body ................................................................................................................................................. 1302 Body Interactions .............................................................................................................................. 1304 Body Interaction ............................................................................................................................... 1306 Chart ................................................................................................................................................ 1307 Commands ....................................................................................................................................... 1307 Comment ......................................................................................................................................... 1309 Connections ..................................................................................................................................... 1309 Connection Group ............................................................................................................................ 1311 Construction Geometry .................................................................................................................... 1313 Contact Debonding .......................................................................................................................... 1313 Contact Region ................................................................................................................................. 1314 Object Properties - Most Structural Analyses ................................................................................ 1316 Object Properties - Explicit Dynamics Analyses ............................................................................ 1317 Object Properties - Thermal and Electromagnetic Analyses .......................................................... 1317 Object Properties - Rigid Body Dynamics Analyses ....................................................................... 1318 Contact Tool (Group) ......................................................................................................................... 1318 Convergence .................................................................................................................................... 1320 Coordinate System ............................................................................................................................ 1321 Coordinate Systems .......................................................................................................................... 1324 Crack ................................................................................................................................................ 1325 Direct FE (Group) .............................................................................................................................. 1327 End Release ...................................................................................................................................... 1328 Environment (Group) ........................................................................................................................ 1329 Fatigue Tool (Group) ......................................................................................................................... 1330 Figure ............................................................................................................................................... 1333 Fluid Surface ..................................................................................................................................... 1334 Fracture ............................................................................................................................................ 1335 Gasket Mesh Control ......................................................................................................................... 1336 Geometry ......................................................................................................................................... 1336 Global Coordinate System ................................................................................................................. 1339 Image ............................................................................................................................................... 1340 Imported Layered Section ................................................................................................................. 1340 Imported Load (Group) ..................................................................................................................... 1342 Imported Remote Loads .................................................................................................................... 1343 Imported Thickness .......................................................................................................................... 1345 Imported Thickness (Group) .............................................................................................................. 1347 Initial Conditions ............................................................................................................................... 1348 Initial Temperature ............................................................................................................................ 1349 Interface Delamination ..................................................................................................................... 1350 Joint ................................................................................................................................................. 1353 Layered Section ................................................................................................................................ 1354 Loads, Supports, and Conditions (Group) ........................................................................................... 1355 Mesh ................................................................................................................................................ 1357 Mesh Connection .............................................................................................................................. 1359 Mesh Control Tools (Group) ............................................................................................................... 1361 Mesh Group (Group) ......................................................................................................................... 1363 Mesh Grouping ................................................................................................................................. 1364 Mesh Numbering .............................................................................................................................. 1364 Modal ............................................................................................................................................... 1365 Model ............................................................................................................................................... 1366 Named Selections ............................................................................................................................. 1367

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Mechanical User's Guide Numbering Control ........................................................................................................................... 1370 Part .................................................................................................................................................. 1371 Path .................................................................................................................................................. 1372 Periodic/Cyclic Region ....................................................................................................................... 1373 Point Mass ........................................................................................................................................ 1375 Pre-Meshed Crack ............................................................................................................................. 1376 Pre-Stress ......................................................................................................................................... 1377 Probe ............................................................................................................................................... 1379 Project .............................................................................................................................................. 1380 Remote Point .................................................................................................................................... 1381 Remote Points .................................................................................................................................. 1383 Result Tracker ................................................................................................................................... 1383 Results and Result Tools (Group) ........................................................................................................ 1385 Solution ............................................................................................................................................ 1389 Solution Combination ....................................................................................................................... 1390 Solution Information ......................................................................................................................... 1391 Spot Weld ......................................................................................................................................... 1391 Spring .............................................................................................................................................. 1393 Stress Tool (Group) ............................................................................................................................ 1395 Surface ............................................................................................................................................. 1397 Symmetry ......................................................................................................................................... 1397 Symmetry Region ............................................................................................................................. 1398 Thermal Point Mass ........................................................................................................................... 1399 Thickness .......................................................................................................................................... 1401 Validation ......................................................................................................................................... 1402 Velocity ............................................................................................................................................ 1404 Virtual Body ...................................................................................................................................... 1405 Virtual Body Group ........................................................................................................................... 1407 Virtual Cell ........................................................................................................................................ 1407 Virtual Hard Vertex ............................................................................................................................ 1408 Virtual Split Edge .............................................................................................................................. 1409 Virtual Split Face ............................................................................................................................... 1410 Virtual Topology ............................................................................................................................... 1410 CAD System Information ...................................................................................................................... 1413 General Information .......................................................................................................................... 1414 Troubleshooting ................................................................................................................................... 1415 General Product Limitations .............................................................................................................. 1415 Problem Situations ............................................................................................................................ 1415 A Linearized Stress Result Cannot Be Solved. ............................................................................... 1416 A Load Transfer Error Has Occurred. ............................................................................................. 1417 Although the Exported File Was Saved to Disk ............................................................................. 1417 Although the Solution Failed to Solve Completely at all Time Points. ............................................ 1417 An Error Occurred Inside the SOLVER Module: Invalid Material Properties ..................................... 1418 An Error Occurred While Solving Due To Insufficient Disk Space ................................................... 1419 An Error Occurred While Starting the Solver Module .................................................................... 1419 An Internal Solution Magnitude Limit Was Exceeded. ................................................................... 1420 An Iterative Solver Was Used for this Analysis ............................................................................... 1420 At Least One Body Has Been Found to Have Only 1 Element ......................................................... 1420 At Least One Spring Exists with Incorrectly Defined Nonlinear Stiffness ........................................ 1421 Animation Does not Export Correctly .......................................................................................... 1421 Application Not Closing as Expected ........................................................................................... 1422 Assemblies Missing Parts 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Mechanical User's Guide CATIA V5 and IGES Surface Bodies ............................................................................................... 1422 Constraint Equations Were Not Properly Matched ........................................................................ 1422 Error Inertia tensor is too large .................................................................................................... 1422 Failed to Load Microsoft Office Application .................................................................................. 1422 Illogical Reaction Results ............................................................................................................. 1422 Large Deformation Effects are Active ........................................................................................... 1423 MPC equations were not built for one or more contact regions or remote boundary conditions .... 1423 One or More Contact Regions May Not Be In Initial Contact .......................................................... 1423 One or more MPC contact regions or remote boundary conditions may have conflicts ................. 1424 One or More Parts May Be Underconstrained ............................................................................... 1424 One or More Remote Boundary Conditions is Scoped to a Large Number of Elements .................. 1425 Problems Unique to Background (Asynchronous) Solutions ......................................................... 1425 Problems Using Solution ............................................................................................................. 1426 Running Norton AntiVirusTM Causes the Mechanical Application to Crash .................................... 1427 The Correctly Licensed Product Will Not Run ................................................................................ 1427 The Deformation is Large Compared to the Model Bounding Box ................................................. 1428 The Initial Time Increment May Be Too Large for This Problem ...................................................... 1428 The Joint Probe cannot Evaluate Results ...................................................................................... 1429 The License Manager Server Is Down ........................................................................................... 1429 Linux Platform - Localized Operating System ............................................................................... 1429 The Low/High Boundaries of Cyclic Symmetry ............................................................................ 1430 The Remote Boundary Condition object is defined on the Cyclic Axis of Symmetry ....................... 1430 The Solution Combination Folder ................................................................................................ 1430 The Solver Engine was Unable to Converge ................................................................................. 1431 The Solver Has Found Conflicting DOF Constraints ...................................................................... 1432 Problem with RSM-Mechanical Connection ................................................................................. 1432 Unable to Find Requested Modes ................................................................................................ 1432 You Must Specify Joint Conditions to all Three Rotational DOFs .................................................... 1433 Recommendations ............................................................................................................................ 1433 A. Glossary of General Terms .................................................................................................................... 1435 B. Tutorials .............................................................................................................................................. 1439 Steady-State and Transient Thermal Analysis of a Circuit Board ........................................................... 1439 Cyclic Symmetry Analysis of a Rotor - Brake Assembly ........................................................................ 1449 Using Finite Element Access to Resolve Overconstraint ...................................................................... 1464 Actuator Mechanism using Rigid Body Dynamics .............................................................................. 1495 Track Roller Mechanism using Point on Curve Joints and Rigid Body Dynamics .................................. 1504 Simple Pendulum using Rigid Dynamics and Nonlinear Bushing ........................................................ 1510 Fracture Analysis of a Double Cantilever Beam (DCB) using Pre-Meshed Crack .................................... 1515 Fracture Analysis of an X-Joint Problem with Surface Flaw using Internally Generated Crack Mesh ...... 1522 Fracture Analysis of a 2D Cracked Specimen using Pre-Meshed Crack ................................................. 1528 Interface Delamination Analysis of Double Cantilever Beam ............................................................... 1536 Delamination Analysis using Contact Based Debonding Capability .................................................... 1555 Nonlinear Static Structural Analysis of a Rubber Boot Seal .................................................................. 1569 C. Data Transfer Mesh Mapping ............................................................................................................... 1595 Mapping Validation ........................................................................................................................... 1612 D. LS-DYNA Keywords Used in an Explicit Dynamics Analysis .................................................................... 1617 Supported LS-DYNA Keywords .......................................................................................................... 1617 LS-DYNA General Descriptions .......................................................................................................... 1646 E. Workbench Mechanical Wizard Advanced Programming Topics ............................................................ 1649 Overview .......................................................................................................................................... 1649 URI Address and Path Considerations ................................................................................................ 1650 Using Strings and Languages ............................................................................................................ 1651

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Mechanical User's Guide Guidelines for Editing XML Files ......................................................................................................... 1652 About the TaskML Merge Process ...................................................................................................... 1652 Using the Integrated Wizard Development Kit (WDK) ......................................................................... 1653 Using IFRAME Elements .................................................................................................................... 1653 TaskML Reference ............................................................................................................................. 1654 Overview Map of TaskML ............................................................................................................. 1654 Document Element ..................................................................................................................... 1655 simulation-wizard ................................................................................................................. 1655 External References ..................................................................................................................... 1656 Merge ................................................................................................................................... 1656 Script .................................................................................................................................... 1656 Object Grouping ......................................................................................................................... 1657 object-group ........................................................................................................................ 1657 object-groups ....................................................................................................................... 1658 object-type ........................................................................................................................... 1658 Status Definitions ........................................................................................................................ 1659 status ................................................................................................................................... 1659 statuses ................................................................................................................................ 1660 Language and Text ...................................................................................................................... 1660 data ...................................................................................................................................... 1660 language .............................................................................................................................. 1660 string .................................................................................................................................... 1661 strings .................................................................................................................................. 1661 Tasks and Events ......................................................................................................................... 1662 activate-event ....................................................................................................................... 1662 task ...................................................................................................................................... 1663 tasks ..................................................................................................................................... 1663 update-event ........................................................................................................................ 1664 Wizard Content ........................................................................................................................... 1664 body ..................................................................................................................................... 1664 group ................................................................................................................................... 1665 iframe ................................................................................................................................... 1666 taskref .................................................................................................................................. 1666 Rules .......................................................................................................................................... 1667 Statements ........................................................................................................................... 1667 and ................................................................................................................................. 1667 debug ............................................................................................................................ 1667 if then else stop .............................................................................................................. 1668 not ................................................................................................................................. 1669 or ................................................................................................................................... 1669 update ........................................................................................................................... 1669 Conditions ............................................................................................................................ 1670 assembly-geometry ........................................................................................................ 1670 changeable-length-unit ................................................................................................. 1670 geometry-includes-sheets ............................................................................................... 1670 level ............................................................................................................................... 1671 object ............................................................................................................................. 1671 zero-thickness-sheet ....................................................................................................... 1672 valid-emag-geometry ..................................................................................................... 1673 enclosure-exists .............................................................................................................. 1673 Actions ................................................................................................................................. 1673 click-button .................................................................................................................... 1674 Release 15.0 - © SAS IP, Inc. 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Mechanical User's Guide display-details-callout ..................................................................................................... 1674 display-help-topic ........................................................................................................... 1675 display-outline-callout .................................................................................................... 1675 display-status-callout ...................................................................................................... 1676 display-tab-callout .......................................................................................................... 1676 display-task-callout ......................................................................................................... 1677 display-toolbar-callout .................................................................................................... 1677 open-url ......................................................................................................................... 1678 select-all-objects ............................................................................................................. 1679 select-field ...................................................................................................................... 1680 select-first-object ............................................................................................................ 1680 select-first-parameter-field .............................................................................................. 1681 select-first-undefined-field .............................................................................................. 1682 select-zero-thickness-sheets ........................................................................................... 1682 select-enclosures ............................................................................................................ 1682 send-mail ....................................................................................................................... 1682 set-caption ..................................................................................................................... 1683 set-icon .......................................................................................................................... 1684 set-status ........................................................................................................................ 1684 Scripting ..................................................................................................................................... 1685 eval ...................................................................................................................................... 1685 Standard Object Groups Reference .................................................................................................... 1686 Tutorials ........................................................................................................................................... 1689 Tutorial: Adding a Link ................................................................................................................. 1689 Tutorial: Creating a Custom Task .................................................................................................. 1691 Tutorial: Creating a Custom Wizard .............................................................................................. 1692 Tutorial: Adding a Web Search IFRAME ......................................................................................... 1693 Completed TaskML Files .............................................................................................................. 1695 Links.xml .............................................................................................................................. 1695 Insert100psi.xml ................................................................................................................... 1695 CustomWizard.xml ................................................................................................................ 1696 Search.htm ........................................................................................................................... 1697 CustomWizardSearch.xml ..................................................................................................... 1698 Wizard Development Kit (WDK) Groups ............................................................................................. 1699 WDK: Tools Group ....................................................................................................................... 1699 WDK: Commands Group .............................................................................................................. 1700 WDK Tests: Actions ...................................................................................................................... 1701 WDK Tests: Flags (Conditions) ...................................................................................................... 1701 F. Material Models Used in Explicit Dynamics Analysis .............................................................................. 1703 Introduction ..................................................................................................................................... 1703 Explicit Material Library ..................................................................................................................... 1705 Density ............................................................................................................................................. 1711 Linear Elastic ..................................................................................................................................... 1711 Isotropic Elasticity ....................................................................................................................... 1711 Orthotropic Elasticity .................................................................................................................. 1712 Viscoelastic ................................................................................................................................. 1712 Test Data .......................................................................................................................................... 1713 Hyperelasticity .................................................................................................................................. 1713 Plasticity ........................................................................................................................................... 1719 Bilinear Isotropic Hardening ........................................................................................................ 1719 Multilinear Isotropic Hardening ................................................................................................... 1720 Bilinear Kinematic Hardening ...................................................................................................... 1720

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Mechanical User's Guide Multilinear Kinematic Hardening ................................................................................................. 1720 Johnson-Cook Strength .............................................................................................................. 1721 Cowper-Symonds Strength ......................................................................................................... 1723 Steinberg-Guinan Strength ......................................................................................................... 1724 Zerilli-Armstrong Strength .......................................................................................................... 1725 Brittle/Granular ................................................................................................................................. 1727 Drucker-Prager Strength Linear ................................................................................................... 1727 Drucker-Prager Strength Stassi .................................................................................................... 1728 Drucker-Prager Strength Piecewise ............................................................................................. 1729 Johnson-Holmquist Strength Continuous .................................................................................... 1730 Johnson-Holmquist Strength Segmented .................................................................................... 1732 RHT Concrete Strength ................................................................................................................ 1734 MO Granular ............................................................................................................................... 1740 Equations of State ............................................................................................................................. 1741 Background ................................................................................................................................ 1741 Bulk Modulus .............................................................................................................................. 1742 Shear Modulus ............................................................................................................................ 1742 Ideal Gas EOS .............................................................................................................................. 1742 Polynomial EOS .......................................................................................................................... 1743 Shock EOS Linear ........................................................................................................................ 1745 Shock EOS Bilinear ...................................................................................................................... 1746 JWL EOS ..................................................................................................................................... 1748 Porosity ............................................................................................................................................ 1750 Porosity-Crushable Foam ............................................................................................................ 1750 Compaction EOS Linear .............................................................................................................. 1753 Compaction EOS Non-Linear ....................................................................................................... 1754 P-alpha EOS ................................................................................................................................ 1756 Failure .............................................................................................................................................. 1759 Plastic Strain Failure .................................................................................................................... 1760 Principal Stress Failure ................................................................................................................. 1760 Principal Strain Failure ................................................................................................................. 1761 Stochastic Failure ........................................................................................................................ 1762 Tensile Pressure Failure ............................................................................................................... 1764 Crack Softening Failure ............................................................................................................... 1764 Johnson-Cook Failure .................................................................................................................. 1767 Grady Spall Failure ...................................................................................................................... 1768 Strength ........................................................................................................................................... 1769 Thermal Specific Heat ....................................................................................................................... 1769 Rigid Materials .................................................................................................................................. 1770 G. Explicit Dynamics Theory Guide ........................................................................................................... 1771 Why use Explicit Dynamics? .............................................................................................................. 1771 What is Explicit Dynamics? ................................................................................................................ 1771 The Solution Strategy .................................................................................................................. 1772 Basic Formulations ...................................................................................................................... 1772 Implicit Transient Dynamics .................................................................................................. 1773 Explicit Transient Dynamics ................................................................................................... 1773 Time Integration ......................................................................................................................... 1774 Implicit Time Integration ....................................................................................................... 1774 Explicit Time Integration ....................................................................................................... 1774 Mass Scaling ......................................................................................................................... 1776 Wave Propagation ....................................................................................................................... 1777 Elastic Waves ........................................................................................................................ 1777 Release 15.0 - © SAS IP, Inc. 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Mechanical User's Guide Plastic Waves ........................................................................................................................ 1777 Shock Waves ......................................................................................................................... 1778 Reference Frame ......................................................................................................................... 1779 Lagrangian and Eulerian Reference Frames ............................................................................ 1779 Eulerian (Virtual) Reference Frame in Explicit Dynamics ......................................................... 1780 Post-Processing a Body with Reference Frame Euler (Virtual) .................................................. 1782 Key Concepts of Euler (Virtual) Solutions ............................................................................... 1783 Multiple Material Stress States ......................................................................................... 1784 Multiple Material Transport ............................................................................................. 1786 Supported Material Properties ........................................................................................ 1786 Known Limitations of Euler Solutions .............................................................................. 1786 Explicit Fluid Structure Interaction (Euler-Lagrange Coupling) ...................................................... 1786 Shell Coupling ...................................................................................................................... 1788 Sub-cycling ........................................................................................................................... 1788 Analysis Settings ............................................................................................................................... 1789 Step Controls .............................................................................................................................. 1789 Damping Controls ....................................................................................................................... 1790 Solver Controls ........................................................................................................................... 1794 Erosion Controls ......................................................................................................................... 1802 Remote Points in Explicit Dynamics ................................................................................................... 1803 Explicit Dynamics Remote Points ................................................................................................. 1803 Explicit Dynamics Remote Boundary Conditions .......................................................................... 1804 References ........................................................................................................................................ 1804 H. Content to be provided ....................................................................................................................... 1807 Introduction ..................................................................................................................................... 1807 Index ...................................................................................................................................................... 1809

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Overview ANSYS Mechanical is a Workbench application that can perform a variety of engineering simulations, including stress, thermal, vibration, thermo-electric, and magnetostatic simulations. A typical simulation consists of setting up the model and the loads applied to it, solving for the model's response to the loads, then examining the details of the response with a variety of tools. The Mechanical application has "objects" arranged in a tree structure that guide you through the different steps of a simulation. By expanding the objects, you expose the details associated with the object, and you can use the corresponding tools and specification tables to perform that part of the simulation. Objects are used, for example, to define environmental conditions such as contact surfaces and loadings, and to define the types of results you want to have available for review. The following Help topics describe in detail how to use the Mechanical application to set up and run a simulation: • Application Interface • Steps for Using the Application • Analysis Types • Specifying Geometry • Setting Up Coordinate Systems • Setting Connections • Configuring Analysis Settings • Setting Up Boundary Conditions • Using Results • Understanding Solving • Commands Objects • Setting Parameters

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Mechanical Application Interface This section describes the elements of the Mechanical Application interface, their purpose and conditions, as well as the methods for their use. The following topics are covered in this section: Mechanical Application Window Windows Management Main Windows Contextual Windows Main Menus Toolbars Interface Behavior Based on License Levels Environment Filtering Customizing the Mechanical Application Working with Graphics Mechanical Hotkeys Wizards

Mechanical Application Window The functional elements of the interface include the following. Window Component

Description

Main Menus (p. 44)

This menu includes the basic menus such as File and Edit.

Standard Toolbar (p. 49)

This toolbar contains commonly used application commands.

Graphics Toolbar (p. 50)

This toolbar contains commands that control pointer mode or cause an action in the graphics browser.

Context Toolbar (p. 53)

This toolbar contains task-specific commands that change depending on where you are in the Tree Outline (p. 3).

Unit Conversion Toolbar (p. 69)

Not visible by default. This toolbar allows you to convert units for various properties.

Named Selection Toolbar (p. 69)

Not visible by default. This toolbar contains options to manage named selections.

Graphics Options Toolbar (p. 69)

This toolbar provides access to general graphics controls such as wireframe and mesh visibility.

Edge Graphics Options (p. 71)

This toolbar provides access to graphics features pertaining to edge display, such as the ability to distinguish mesh connectivity.

Tree Outline (p. 3)

Outline view of the simulation project. Always visible. Location in the outline sets the context for other controls. Provides access to object's context menus. Allows renaming of objects. Establishes what details display in the Details View (p. 11).

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Application Interface Window Component

Description

Details View (p. 11)

The Details View (p. 11) corresponds to the Outline selection. Displays a details window on the lower left panel of the Mechanical application window which contains details about each object in the Outline.

Geometry Window (p. 20)

Displays and manipulates the visual representation of the object selected in the Outline. This window displays: • 3D Geometry • 2D/3D Graph • Spreadsheet • HTML Pages

Note The Geometry window may include splitter bars for dividing views. Reference Help

Opens an objects reference help page for the highlighted object.

Status Bar

Brief in-context tip. Selection feedback.

Splitter Bar

Application window has up to three splitter bars.

Windows Management The Mechanical window contains window panes that house graphics, outlines, tables, object details, and other views and controls. Window management features allow you to move, resize, tab-dock, and auto-hide window panes. A window pane that is "tab-docked" is collapsed and displayed at the side of the application interface. Auto-hide indicates that a window pane (or tab-docked group of panes) automatically collapses when not in use.

Auto-Hiding Panes are either pinned or unpinned . Toggle this state by clicking the icon in the pane title bar. A pinned pane occupies space in the window. An unpinned pane collapses to a tab on the periphery of the window when inactive. To examine an unpinned pane, move the mouse pointer over the tab. This causes the pane to open overtop of any other open window panes. Holding the mouse pointer over the tab keeps the tab visible. Clicking the tab actives the window pane (also causing it to remain visible). Pin the pane to restore it to its open state.

Moving and Docking Drag a window’s title bar to move and undock a window pane. Once you begin to drag the window, a number of dock targets (blue-filled arrows and circle) appear in the interface window. At this point you:

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Main Windows 1.

Move the mouse pointer over a target to preview the resulting location for the pane. Arrow targets indicate adjacent locations; a circular target allows tab-docking of two or more panes (to share screen space).

2.

Release the button on the target to move the pane. You can abort the drag operation by pressing the ESC key.

Tip You can also double-click a window’s title bar to undock the window and move it freely around the screen. Once undocked, you can resize the window by dragging its borders/corners.

Restore Original Window Layout Choose Rest Layout from the View>Windows menu to return to the default/original pane configuration.

Main Windows In addition to the menu and toolbar structure of the interface, there are three primary graphical user interface areas of the application, and include: • Tree Outline • Details View • Geometry Window Selecting a tree object in the Outline displays attributes and controls for the selected object in the Details view. The Geometry window displays your CAD model and, based on the tree object selected, displays pertinent information about object specifications and how they relate to the displayed geometry. The Geometry window is considered a “tab”. In addition to Geometry, there is a Print Preview tab and a Report Preview tab. These tabs provide alternative views of the currently selected Outline object. These user interface elements are described in more detail in the following sections: Tree Outline Details View Geometry Window Print Preview Report Preview

Tree Outline The object Tree Outline matches the logical sequence of simulation steps. Object sub-branches relate to the main object. For example, an analysis environment object, such as Static Structural, contains loads. You can right-click on an object to open a context menu which relates to that object. You can rename objects prior to and following the solution process. Refer to the Objects Reference section of the Help for a listing and description of all of the objects available in the application. The following is an example of the Outline window pane:

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Application Interface

Note Numbers preceded by a space at the end of an object's name are ignored. This is especially critical when you copy objects or duplicate object branches. For example, if you name two force loads as Force 1 and Force 2, then copy the loads to another analysis environment, the copied loads are automatically renamed Force and Force 2. However, if you rename the loads as Force_1 and Force_2, the copied loads retain the same names as the two original loads. The following topics present further details related to the tree outline. Understanding the Tree Outline Correlating Tree Outline Objects with Model Characteristics Suppressing Objects Filtering the Tree

Understanding the Tree Outline The Tree Outline uses the following conventions: • Icons appear to the left of objects in the tree. Their intent is to provide a quick visual reference to the identity of the object. For example, icons for part and body objects (within the Geometry object folder) can help distinguish solid, surface and line bodies. • A symbol to the left of an item's icon indicates that it contains associated subitems. Click to expand the item and display its contents. • To collapse all expanded items at once, double-click the Project name at the top of the tree. • Drag-and-drop function to move and copy objects. • To delete a tree object from the Tree Outline (p. 3), right-click on the object and select Delete. A confirmation dialog asks if you want to delete the object.

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Main Windows • Filter tree contents and expand the tree by setting a filter and then clicking the Expand on Refresh button.

Status Symbols As described below, a small status icon displays to the left of the object icon in the Tree Outline (p. 3). Status Symbol Name

Symbol

Example A load requires a nonzero magnitude.

Underdefined

Load attachments may break during an Update.

Error

Face could not be mapped meshed, or mesh of face pair could not be matched.

Mapped Face or Match Control Failure

The object is defined properly and/or any specific action on the object is successful.

Ok

Equivalent to "Ready to Answer!"

Needs to be Updated

A body or part is hidden.

Hidden

The symbol appears for a meshed body within the Geometry folder, or for a multibody part whose child bodies are all meshed.

Meshed

An object is suppressed.

Suppress

• Yellow lightning bolt: Item has not yet been solved. • Green lightning bolt: Solve in progress. • Green check mark: Successful solution. • Red lightning bolt: Failed solution. An overlaid pause icon indicates the solution could resume with the use of restart points.

Solve

• Green down arrow: Successful background solution ready for download. • Red down arrow: Failed background solution ready for download. See also Tree Outline (p. 3).

Note The state of an environment folder can be similar to the state of a Solution folder. The solution state can indicate either solved (check mark) or not solved (lightening bolt) depending on whether or not an input file has been generated.

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Correlating Tree Outline Objects with Model Characteristics The Go To feature provides you with instant visual correlation of objects in the tree outline as they relate to various characteristics of the model displayed in the Geometry window. To activate this feature, right-click anywhere in the Geometry window, choose Go To, then choose an option in the context menu. In some cases (see table below), you must select geometry prior to choosing the Go To feature. The resulting objects that match the correlation are highlighted in the tree outline and the corresponding geometry is highlighted on the model. For example, you can identify contact regions in the tree that are associated with a particular body by selecting the geometry of interest and choosing the Contacts for Selected Bodies option. The contact region objects associated with the body of the selected items will be highlighted in the tree and the contact region geometry will be displayed on the model. Several options are filtered and display only if specific conditions exist within your analysis. The Go To options are presented in the following table along with descriptions and conditions under which they appear in the context menu. Go To Option

Description / Application

Required Conditions for Option to Appear

Corresponding Bodies in Tree

Identifies body objects in the tree that correspond to selections in the Geometry window.

At least one vertex, edge, face, or body is selected.

Hidden Bodies in Tree

Identifies body objects in the tree that correspond to hidden bodies in the Geometry window.

At least one body is hidden.

Suppressed Bodies in Tree

Identifies body objects in the tree that correspond to suppressed bodies in the Geometry window.

At least one body is suppressed.

Bodies Without Contacts in Tree

Identifies bodies that are not in contact with any other bodies. When you are working with complex assemblies of more than one body, it is helpful to find bodies that are not designated to be in contact with any other bodies, as they generally cause problems for a solution because they are prone to rigid body movements.

Parts Without Contacts in Identifies parts that are not Tree in contact with any other parts. When you are working with complex assemblies of more than one multibody part, it is

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More than one body in an assembly.

More than one part in an assembly.

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Main Windows Go To Option

Description / Application

Required Conditions for Option to Appear

helpful to find parts that are not designated to be in contact with any other parts. For example, this is useful when dealing with shell models which can have parts that include many bodies each. Using this feature is preferred over using the Bodies Without Contact in Tree option when working with multibody parts mainly because contact is not a typical requirement for bodies within a part. Such bodies are usually connected by shared nodes at the time of meshing. Contacts for Selected Bodies

Identifies contact region objects in the tree that are associated with selected bodies.

Contacts Common to Selected Bodies

Identifies contact region objects in the tree that are shared among selected bodies.

Joints for Selected Bodies Identifies joint objects in the tree that are associated with selected bodies. Joints Common to Selected Bodies

Identifies joint objects in the tree that are shared among selected bodies.

At least one vertex, edge, face, or body is selected.

Springs for Selected Bod- Identifies spring objects in the tree ies that are associated with selected bodies. Mesh Controls for Selected Bodies

Identifies mesh control objects in the tree that are associated with selected bodies.

Mesh Connections for Selected Bodies

Highlights mesh connection objects in the tree that are associated with the selection.

At least one vertex, edge, face, or body is selected and at least one mesh connection exists.

Mesh Connections Common to Selected Bodies

Highlights mesh connection objects in the tree that are shared among selected bodies.

At least one vertex, edge, face, or body is selected.

Field Bodies in Tree

Identifies enclosure objects in the At least one body is an enclosure. tree that are associated with selected bodies.

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Application Interface Go To Option

Description / Application

Required Conditions for Option to Appear

Bodies With One Element Through the Thickness

Identifies bodies in the tree with one element in at least two directions (through the thickness).

At least one body with one element in at least two directions (through the thickness).

This situation can produce invalid results when used with reduced integration. See At Least One Body Has Been Found to Have Only 1 Element (p. 1420) in the troubleshooting section for details. Thicknesses for Selected Faces

Identifies objects with defined thicknesses in the tree that are associated with selected faces.

At least one face with defined thickness is selected.

Body Interactions for Selected Bodies

Identifies body interaction objects At least one body interaction is in the tree that are associated with defined and at least on body is selected bodies. selected.

Body Interactions Common to Selected Bodies

Identifies body interaction objects At least one body interaction is in the tree that are shared with defined and at least on body is selected bodies. selected.

Suppressing Objects Certain objects in the Mechanical application tree outline can be suppressed, meaning that they can be individually removed from any further involvement in the analysis. For example, suppressing a part removes the part from the display and from any further loading or solution treatment. For Geometry and Environment folders, the objects that you Suppress are removed from the solved process. For Solution folder, if you suppress a solved result object, the result information will be deleted for the suppressed result object. The suppressed object is not considered in the subsequent result evaluations. You can use this feature to leave out an under-defined result object and obtain values for other results under Solution. You can Unsuppress the result object and evaluate all results to get an updated result value. To suppress results objects from the context menu, right-click the result object, and then click Suppress. Click Yes to suppress the object, or No to cancel the message box.

How to Suppress or Unsuppress Objects If available, set the Suppressed option in the Details view to Yes. Conversely, you can unsuppress items by setting the Suppressed option to No. You can also suppress/unsuppress these items through context menu options available via a right mouse button click. Included is the context menu option Invert Suppressed Body Set, which allows you to reverse the suppression state of all bodies (unsuppressed bodies become suppressed and sup-

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Main Windows pressed bodies become unsuppressed). You can suppress the bodies in a named selection using either the context menu options mentioned above, or through the Named Selection Toolbar. Another way to suppress a body is by selecting it in the graphics window, then using a right mouse button click in the graphics window and choosing Suppress Body in the context menu. Conversely, the Unsuppress All Bodies option is available for unsuppressing bodies. Options are also available in this menu for hiding or showing bodies. Hiding a body only removes the body from the display. A hidden body is still active in the analysis.

Filtering the Tree At the top of the Tree Outline window is the Tree Filter toolbar.

This toolbar enables you to filter tree items by either showing or hiding objects which match one or more search terms. Filtering options include the following: Filter Type

Description

Name

Filters the tree for or removes one or more specified search terms.

Tag

Filters for tree objects marked with one or more specified tag names. See the Tagging Objects section.

Type

Provides a drop-down list of objects for which you can filter. The options include: • All - this default option displays all tree objects and requires you to make a selection to initiate the filter process. • Results • Boundary Conditions • Connections • Commands

State

Provides a drop-down list of filters for a selected state. State options include: • All states

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Application Interface Filter Type

Description • Suppressed • Not Licensed • Underdefined

Coordinate System

Provides a drop-down list of all coordinate systems in the tree. You can select to filter for All coordinate system objects or specify an individual coordinate system object. The filter displays all objects within the tree that employ the individually selected coordinate system.

Note Note that all coordinate systems display in the filter. There are cases where an object does not have a coordinate system property in its Details view, but it does have an associated coordinate system as a requirement. As a result, it may appear as though an unaccounted for coordinate system is present. This is especially true for the Global Coordinate System.

Note Performing a search for an object that does not exist in the tree results in all objects being displayed.

Toolbar Buttons The filter toolbar buttons perform the following actions. Refresh Search Refreshes the search criteria that you have specified following changes to the environment. Clear Search Clear the filter and returns the tree to the full view. Remove Turned off by default. Depressing this button turns the feature on and off. When active, it removes the objects in question from the tree display. Expand on Refresh Turned on by default so that your modifications are automatically captured. You may "un-click" this option to turn it off.

Using the Filter Feature To filter the tree outline: 1.

Select a filter type: • Name

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Main Windows • Tag • Type • State • Coordinate System 2.

For Name and Tag, enter one or more search terms. For the other filters, select an option from the drop-down list to further specify your inquiry.

3.

Click the Refresh Search button (or press Enter) to execute your search. If you want to eliminate content from the tree, click the Remove button and then click Refresh Search to remove the requested objects.

4.

When searching, the tree displays only objects matching your search criteria. If you enter multiple search terms, the tree shows only objects matching all of the specified terms. When removing objects, the requested objects do not display.

Details View The Details view is located in the bottom left corner of the window. It provides you with information and details that pertain to the object selected in the Tree Outline (p. 3). Some selections require you to input information (e.g., force values, pressures). Some selections are drop-down dialogs, which allow you to select a choice. Fields may be grayed out. These cannot be modified. The following example illustrates the Details view for the object called Geometry.

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For more information, see: Features (p. 13) Header (p. 13) Categories (p. 13) Undefined or Invalid Fields (p. 14) Decisions (p. 14) Text Entry (p. 15) 12

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Main Windows Numeric Values (p. 17) Ranges (p. 17) Increments (p. 17) Geometry (p. 18) Exposing Fields as Parameters (p. 19) Options (p. 19)

Features The Details view allows you to enter information that is specific to each section of the Tree Outline. It automatically displays details for branches such as Geometry, Model, Connections, etc. Features of the Details view include: • Collapsible bold headings. • Dynamic cell background color change. • Row selection/activation. • Auto-sizing/scrolling. • Sliders for range selection. • Combo boxes for boolean or list selection. • Buttons to display dialog box (e.g. browse, color picker). • Apply / Cancel buttons for geometry selection. • Obsolete items are highlighted in red.

Header The header identifies the control and names the current object.

The header is not a windows title bar; it cannot be moved.

Categories Category fields extend across both columns of the Details Pane:

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This allows for maximum label width and differentiates categories from other types of fields. To expand or collapse a category, double-click the category name.

Undefined or Invalid Fields Fields whose value is undefined or invalid are highlighted in yellow:

Decisions Decision fields control subsequent fields:

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Note The left column always adjusts to fit the widest visible label. This provides maximum space for editable fields in the right column. You can adjust the width of the columns by dragging the separator between them.

Text Entry Text entry fields may be qualified as strings, numbers, or integers. Units are automatically removed and replaced to facilitate editing:

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Inappropriate characters are discarded (for example, typing a Z in an integer field). A numeric field cannot be entered if it contains an invalid value. It is returned to its previous value. Separator Clarification Some languages use “separators” within numerical values whose meanings may vary across different languages. For example, in English the comma separator [,] indicates “thousand” (“2,300” implies “two thousand three hundred”), but in German the comma separator indicates “decimal” (“2,300” implies “two and three tenths”, equivalent to “2.300” in English). To avoid misinterpretation of numerical values you enter that include separators, you are asked to confirm such entries before they are accepted. For example, in English, if you enter “2,300”, you receive a message stating the following: “Entered value is 2,300. Do you want to accept the correction proposed below? 2300 To accept the correction, click Yes. To close this message and correct the number yourself, click No.

Note If an invalid entry is detected, an attempt is made to interpret the entry as numerical and you receive the message mentioned above if an alternate value is found. If an invalid value is entered, for example "a1.3.4", and no numerical alternative is found, the entry is rejected and the previous value is re-displayed.

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Main Windows

Numeric Values You can enter numeric expressions in the form of a constant value or expression, tabular data, or a function. See Defining Boundary Condition Magnitude (p. 848) for further information.

Ranges If a numeric field has a range, a slider appears to the right of the current value:

If the value changes, the slider moves; if the slider moves the value updates.

Increments If a numeric field has an increment, a horizontal up/down control appears to the right of the current value:

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The arrow button controls behave the same way a slider does.

Geometry Geometry fields filter out inappropriate selection modes. For example, a bearing load can only be scoped to a face. Geometries other than face will not be accepted.

Direction fields require a special type of selection:

Clicking Apply locks the current selection into the field. Other gestures (clicking Cancel or selecting a different object or field) do not change the field's preexisting selection.

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Main Windows

Exposing Fields as Parameters A P appears beside the name of each field that may be treated as a parameter. Clicking the box exposes the field as a parameter. For more information, see Parameterizing a Variable (p. 19).

Options Option fields allow you to select one item from a short list. Options work the same way as Decisions (p. 14), but don't affect subsequent fields. Options are also used for boolean choices (true/false, yes/no, enabled/disabled, fixed/free, etc.) Double-clicking an option automatically selects the next item down the list. Selecting an option followed by an ellipsis causes an immediate action.

Parameterizing a Variable Variables that you can parameterize display in the interface with a check box. Clicking the check box displays a blue capital "P", as illustrated below.

The boxes that appear in the Mechanical application apply only to the Parameter Workspace. Checking or unchecking these boxes will have no effect on which CAD parameters are transferred to Design Exploration. For more information, see "Setting Parameters" (p. 1151).

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Geometry Window The Geometry window displays the geometry model. All view manipulation, geometry selection, and graphics display of a model occurs in this window, which contains: • 3D Graphics. • A scale ruler. • A legend and a triad control (when you display the solution). • Contour results objects.

Note When you insert a Comment, the Geometry window splits horizontally; the HTML comment editor displays in the bottom of the window, and the geometric representation of the model displays at the top. For more information about editing comments, refer to the Comment object reference.

Features of the Geometry window are described in the following sections: Viewing the Legend

Displaying Shells for Large Deflections The display of shells may become distorted for large deformations such as in large deflection, explicit dynamics analyses, etc. A workaround is to disable shell thickness by toggling View> Thick Shells and Beams on the Main Menus (p. 44). Or, set a Workbench variable, UsePseudoShellDisp = 1, via Tools> Variable Manager. It may be necessary to toggle the deformation scaling from True Scale to Undeformed to True Scale again. Note that this option requires True Scaling to work properly.

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Viewing the Legend To view the legend, confirm that Legend is selected in the View menu. The legend is displayed in the top left corner of the graphics window when you select an object in the tree outline. Note that the legend is not accessible via any of the toolbars in any of the modules.

Repositioning Legend To reposition the legend within the graphics window, select the legend with your mouse, hold down the left mouse button and drag the mouse. Note that the multiple view window configuration does not allow for the legend to be permanently saved in a unique location. Resumption of a database file and toggling between a single view and multiple views will result in the legend being saved to its default position in the upper left corner of the graphics window.

Discrete Legends in the Mechanical Application • Geometry Legend: Contents is driven by Display Style selection in the Details view panel. • Joint Legend: Depicts the free degrees of freedom characteristic of the type of joint. • Results Legend: Content is accessible via the right mouse when the legend for a solved object in the Solution folder is selected.

Print Preview Print Preview runs a script to generate an HTML page and image. The purpose of the Print Preview tab is to allow you to view your results or graphics image.

The title block is an editable HTML table. The table initially contains the Author, Subject, Prepared For and Date information supplied from the details view of the Project tree node. To change or add this information, double click inside the table. The information entered in the table does not propagate any changes back to the details view and is not saved after exiting the Print Preview tab. The image is generated in the same way as figures in Report.

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Report Preview The Report Preview tab enables you to create a report based on the analyses in the Tree Outline. This report selects items in the Tree Outline, examines the worksheets for it, then appends any material data used in the analysis. The report generation process starts immediately, and, once started, it must run to completion before you can begin working in the interface again.

You can click the Report Preview tab to create a report that covers all analyses in the Tree Outline. The process starts immediately. Unlike prior report generators, this system works by extracting information from the user interface. It first selects each item in the Outline, then examines worksheets in a second pass, and finally appends any material data used in the analysis. The material data will be expressed in the Workbench standard unit system which most closely matches the Mechanical application unit system. Once started the report generation process must run to completion. Avoid clicking anywhere else in Workbench during the run because this will stop the report process and may cause an error. This approach to reporting ensures consistency, completeness, and accuracy. This section examines the following Report Preview topics: Publishing the Report Sending the Report Comparing Databases Customizing Report Content

Tables Most tables in the report directly correspond to the Details of an object or set of related objects. Object names appear across the top of the tables. By default, tables contain no more than six columns. This limit increases the likelihood that tables will fit on the screen and on printed pages. In the Report Options dialog you can increase or decrease the limit. For example, you may allow more columns if object names take up little space, if you have a high resolution screen, or print in landscape layout. The minimum is two columns, in which case no grouping of objects occurs and the Contents is equivalent to the Outline.

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Main Windows The system merges identical table cells by default. This reduces clutter and helps to reveal patterns. You can disable this feature in the Report Options dialog.

Note The Report Preview feature does not display table entries from the nonlinear joint stiffness matrix.

Figures and Images Figures and Images appear in the report as specified in the Outline. The system automatically inserts charts as needed. The system creates all bitmap files in PNG format. You may change the size of charts and figures in the Report Options dialog. For example, you may specify smaller charts due to few data points or bigger figures if you plan to print on large paper. For best print quality, increase the Graphics Resolution in the Report Options dialog.

Publishing the Report Click the Publish toolbar button to save your report as a single HTML file that includes the picture files in a given folder, or as an HTML file with a folder containing picture files. The first option produces a single MHT file containing the HTML and pictures. MHT is the same format used by Internet Explorer when a page is saved as a “Web Archive”. Only Internet Explorer 5.5 or later on Windows supports MHT. For the other two options, the HTML file is valid XHTML 1.0 Transitional. Full support for MHT file format by any other browser cannot be guaranteed.

Sending the Report Click the Send To button to send the report as an E-mail attachment, or to open the report in Microsoft Word or import the figures into Microsoft PowerPoint. When emailing, a single MHT file is automatically attached. Note that some email systems may strip or filter MHT files from incoming messages. If this occurs, email a ZIP archive of a published report or email the report from Microsoft Word. Sending a report to Word is equivalent to opening a published HTML file in the application. Sending a report to PowerPoint creates a presentation where one figure or image appears per slide. No other data is imported.

Comparing Databases Because the report content directly corresponds to the user interface, it is easy to determine exactly how two databases differ. Generate a report for the first database, open it in Word, save and exit. Open the report for the second database in Word and choose Tools>Compare Documents. In the dialog, uncheck the Find Formatting box and select the first file. Word highlights the differences, as illustrated here:

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Application Interface

Customizing Report Content Report customization falls into two categories: preferences in the Report Options dialog and the ability to run a modified report generator from a local or network location. This ability to externalize the system is shared by the Mechanical Wizard. It allows for modifications outside of the installation folder and reuse of a customized system by multiple users. To run report externally: 1. Copy the following folder to a different location: Program Files\ANSYS Inc\v150\AISOL\DesignSpace\DSPages\Language\en-us\Report2006. 2. Specify the location under Custom Report Generator Folder in the Report Options (for example: \\server\copied_Report2006_folder). The easiest customization is to simply replace Logo.png. The system uses that image on the wait screen and on the report cover page. The file Template.xml provides the report skeleton. Editing this file allows: • Reformatting of the report by changing the CSS style rules. • Addition of standard content at specific points inside the report body. This includes anything supported by XHTML, including images and tables. The file Rules.xml contains editable configuration information: • Standard files to include and publish with reports. The first is always the logo; other files could be listed as the images used for custom XHTML content. • Rules for excluding or bolding objects in the Contents. • Rules for applying headings when objects are encountered. • Selective exclusion of an object’s details. For example, part Color (extracted as a single number) isn’t meaningful in a report. • Exclusion of Graph figures for certain objects. This overrides the other four criteria used to decide if a Graph figure is meaningful. • Rules against comparing certain types of objects. • Object states that are acceptable in a “finalized” report. 24

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Contextual Windows • Search and replace of Details text. For example, the report switches "Click to Change" to "Defined". This capability allows for the use of custom terminology. • Insertion of custom XHTML content based on object, analysis and physics types, and whether the content applies to the details table, the chart or the tabular data. For example, report includes a paragraph describing the modal analysis bar chart. All files in the Report2006 folder contain comments detailing customization techniques.

Contextual Windows A number of other windows are available. Some appear when specific tools are activated; others are available from the View>Windows menu. This section discusses the following windows: Selection Information Window Worksheet Window Graph and Tabular Data Windows Messages Window Graphics Annotation Window Section Planes Window Manage Views Window The Mechanical Wizard Window

Selection Information Window The Selection Information window provides a quick and easy way for you to interrogate and find geometric information on items that you have selected on the model. The following topics are covered in this section: Activating the Selection Information Window Understanding the Selection Modes Using the Selection Information Window Toolbar Selecting, Exporting, and Sorting Data

Activating the Selection Information Window You can display the Selection Information window using any of the following methods: • Select the Selection Information button on the Standard Toolbar (p. 49). • Choose View>Windows>Selection Information from the Main Menus (p. 44). • Double-click the field on the Status Bar that displays the geometry description.

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Application Interface

An example Selection Information window is illustrated below.

Understanding the Selection Modes The supported selection modes are vertex, edge, face, body, and coordinate. Reported information for each mode is described below.

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Contextual Windows

Vertex Individual vertex location and average location are reported. If two vertices are selected, their distance and x, y, z distances are reported. The bodies that the vertex attaches to are also reported.

Node The information displayed for selected node is similar to a vertex with addition of the Node ID.

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Application Interface

Edge Combined and individual edge length and centroid are reported. The bodies that the edge attaches to are reported. The type of the edge is also reported. If an edge is of circle type, the radius of the edge is reported.

Face Combined and individual area and centroid are reported. The bodies that the face attaches to are reported. The type of the face is reported. If a face is of cylinder type, the radius of the face is also reported.

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Contextual Windows

Body Combined and individual volume, mass, and centroid are reported. The body name is reported. Your choice of the mass moment of inertia in the selected coordinate system or the principal is also reported. The choice is provided in the Selection Information Column Control dialog box (accessible from the Using the Selection Information Window Toolbar (p. 33)).

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Application Interface

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Contextual Windows

Coordinate If there is a mesh present, the picked point location and the closest mesh node ID and location are reported.

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Application Interface

In the case of a surface body model, the closest node will be located on the non-expanded mesh (that can be seen if you turn off the option View> Thick Shells and Beams). Non-expanded shell view:

Expanded shell view:

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Contextual Windows

Using the Selection Information Window Toolbar The toolbar located at the top of the Selection Information window includes the following controls:

Each of these controls is described below.

Coordinate System A Coordinate System drop down selection box is provided on the toolbar. You can select the coordinate system under which the selection information is reported. The centroid, location, and moment of inertia information respect the selected coordinate system.

For example, if a cylindrical coordinate system is selected, the vertex location is reported using the cylindrical coordinates.

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Application Interface

Selection Information Column Control If you click the Selection Information Column Control, a column control dialog box appears to give you control over what columns are visible and what columns you can hide. The choices that you made with the column control are retained for the application.

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Contextual Windows

Note The Moment of Inertia option is unchecked by default. The following example shows the effects of un-checking the centroid for face.

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Application Interface

Selection Information Row Control The Selection Information Row Control has three options: Show Individual and Summary, Show Individual, and Show Summary. Depending upon your choice, the individual and/or summary information is reported.

Selecting, Exporting, and Sorting Data This section describes how you can reselect rows, export data, and sort data in the Selection Information window. Each function is described below.

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Contextual Windows

Reselect Right click to reselect the highlighted rows.

Export Right click to export the table to a text file or Excel file.

Sort Click on the column header to sort the table.

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Application Interface

Worksheet Window The worksheet presents you with information about objects in the tree in the form of tables, charts and text, thereby supplementing the Details view. It is typically intended to summarize data for a collection of objects (for example, the Connections folder worksheet reveals the inputs for all contacts, joints and others) or to receive tabular inputs (for example, to specify the coefficients and the analyses to include in Solution Combinations).

Behavior • Dockable Worksheet By default, when you select an applicable object in the tree, a dockable Worksheet window displays alongside the Geometry window, allowing you to review both at once. You may, however, disable the display of the Worksheet window using the Worksheet toolbar button (see below). This preference is persisted in future sessions of the product. There are specific objects that ignore the preference, as outlined below. Worksheet Function

Worksheet Behavior When Object is Selected

Example Objects

Data input and display information

Automatically appears and gains focus

Constraint Equation, Solution Combination

Display information related to object settings

Automatically appears but does not gain focus

Analysis Settings

Display information related to objects within a folder

Appears only if display is Geometry folder, Contact folder turned on manually using the Worksheet toolbar button (see below)

• Worksheet Toolbar Button

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Contextual Windows For tree objects that include an associated Worksheet, the Worksheet button on the standard toolbar allows you to toggle the Worksheet window display on or off. The button is not available (grayed out) for objects that do not include a Worksheet. Worksheets designed to display many data items do not automatically display the data. The data readily appears however when you click the Worksheet button. This feature applies to the worksheets associated with the following object folders: Geometry, Coordinate System, Contact, Remote Points, Mesh, and Solution.

Features • Go To Selected items This useful feature allows you to find items in either the tree or Geometry window that match one or more rows of the worksheet. If the worksheet displays a tabular summary of a number of objects, select the rows of interest, right-click, and choose Go To Selected Items in Tree to instantly highlight items that match the contents of the Name column (leftmost column). Control is thus transferred to the tree or Geometry window, as needed. • Viewing Selected Columns When a worksheet includes a table with multiple columns, you can control which columns to display. To do so, right-click anywhere inside the table. From the context menu, check the column names of interest to activate their display. Some columns may ignore this setting and remain hidden should they be found inapplicable. To choose the columns that will display, right mouse click anywhere inside the worksheet table. From the context menu, click on any of the column names. A check mark signifies that the column will appear. There are some columns in the worksheet that will not always be shown even if you check them. For example, if all contact regions have a Pinball Region set to Program Controlled, the Pinball Radius will not display regardless of the setting.

Graph and Tabular Data Windows Whenever you highlight the following objects in the Mechanical application tree, a Graph window and Tabular Data window appear beneath the Geometry window. • Analysis Settings • Loads • Contour Results • Probes • Charts These windows are designed to assist you in managing analysis settings and loads and in reviewing results. The Graph window provides an instant graphical display of the magnitude variations in loads and/or results, while the Tabular Data window provides instant access to the corresponding data points. Below are some of the uses of these windows.

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Application Interface

Analysis Settings For analyses with multiple steps, you can use these windows to select the step(s) whose analysis settings you want to modify. The Graph window also displays all the loads used in the analysis. These windows are also useful when using restarts. See Solution Restarts (p. 1032) for more information.

Loads Inserting a load updates the Tabular Data window with a grid to enable you to enter data on a perstep basis. As you enter the data, the values are reflected in the Graph window.

A check box is available for each component of a load in order to turn on or turn off the viewing of the load in the Graph window. Components are color-coded to match the component name in the Tabular Data window. Clicking on a time value in the Tabular Data window or selecting a row in the Graph window will update the display in the upper left corner of the Geometry window with the appropriate time value and load data. As an example, if you use a Displacement load in an analysis with multiple steps, you can alter both the degrees of freedom and the component values for each step by modifying the contents in the Tabular Data window as shown above. If you wish for a load to be active in some steps and removed in some other steps you can do so by following the steps outlined in Activation/Deactivation of Loads (p. 637).

Contour Results and Probes For contour results and probes, the Graph and Tabular Data windows display how the results vary over time. You can also choose a time range over which to animate results. Typically for results the minimum and maximum value of the result over the scoped geometry region is shown. To view the results in the Geometry window for the desired time point, select the time point in the Graph window or Tabular Data window, then click the right mouse button and choose Retrieve Results. The Details view for the chosen result object will also update to the selected step.

Charts With charts, the Graph and Tabular Data windows can be used to display loads and results against time or against another load or results item.

Context Menu Options Presented below are some of the commonly used options available in a context menu that displays when you click the right mouse button within the Graph window and/or the Tabular Data window. The options vary depending on how you are using these windows (for example, loads vs. results). • Retrieve This Result: Retrieves and presents the results for the object at the selected time point.

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Contextual Windows • Insert Step: Inserts a new step at the currently selected time in the Graph window or Tabular Data window. The newly created step will have default analysis settings. All load objects in the analysis will be updated to include the new step. • Delete Step: Deletes a step. • Copy Cell: Copies the cell data into the clipboard for a selected cell or group of cells. The data may then be pasted into another cell or group of cells. The contents of the clipboard may also be copied into Microsoft Excel. Cell operations are only valid on load data and not data in the Steps column. • Paste Cell: Pastes the contents of the clipboard into the selected cell, or group of cells. Paste operations are compatible with Microsoft Excel. • Delete Rows: Removes the selected rows. In the Analysis Settings object this will remove corresponding steps. In case of loads this modifies the load vs time data. • Select All Steps: Selects all the steps. This is useful when you want to set identical analysis settings for all the steps. • Select All Highlighted Steps: Selects a subset of all the steps. This is useful when you want to set identical analysis settings for a subset of steps. • Activate/Deactivate at this step!: This allows a load to become inactive (deleted) in one or more steps. By default any defined load is active in all steps. • Zoom to Range: Zooms in on a subset of the data in the Graph window. Click and hold the left mouse at a step location and drag to another step location. The dragged region will highlight in blue. Next, select Zoom to Range. The chart will update with the selected step data filling the entire axis range. This also controls the time range over which animation takes place. • Zoom to Fit: If you have chosen Zoom to Range and are working in a zoomed region, choosing Zoom to Fit will return the axis to full range covering all steps. Result data is charted in the Graph window and listed in the Tabular Data window. The result data includes the Maximum and Minimum values of the results object over the steps.

Exporting Data Export Tabular Data Most of the loads and results in the Mechanical application are supported through the Graph and Tabular data windows. You can export the data in the Tabular Data window in a Text and Excel File Format. To export the data in the table, right-click the table, and then select Export. The right-click menu also provides copy and paste features for this same purpose.

Export Model Information You can also export a variety of model information to a tab delimited file that Excel can read directly. The following objects allow exporting without access to worksheet data: Contour Results Node-Based Named Selections Element-Based Named Selections Imported Loads Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Application Interface The following objects require the worksheet data to be active in order to export: Connections Contact Group Contact Initial Information Contact Tool Convergence Coordinate Systems Fatigue Sensitivities Frequency Response Geometry Mesh Solution Thermal Condition

Note When you select Top/Bottom as the Shell setting in the Details view for a surface body and export the result contours (such as stresses and strains), the export file contains two results for every node on a shell element. The first result is for the bottom face and the second result is for the top face. Steps to export 1.

Select an object in the tree.

2.

Click the Worksheet to give it focus (if applicable).

3.

Right-mouse click the selected object in the tree to produce the menu, then select Export.

4.

Specify a file name for the Excel file and save the file. Once saved, Excel opens automatically if installed on your computer.

Note You must right-mouse click on the selected object in the tree to use this Export feature. On Windows platforms, if you have the Microsoft Office 2002 (or later) installed, you may see an Export to Excel option if you right-mouse click in the Worksheet. This is not the Mechanical application Export feature but rather an option generated by Microsoft Internet Explorer.

Options Settings The Export the Mechanical application settings in the Options dialog box allows you to: Automatically Open Excel (Yes by default) Include Node Numbers (Yes by default) Include Node Location (No by default)

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Contextual Windows

Messages Window The Messages Window is a Mechanical application feature that prompts you with feedback concerning the outcome of actions you have taken in the Mechanical application. For example, Messages display when you resume a database, Mesh a model, or when you initiate a Solve. Messages come in three forms: • Error • Warning • Information By default the Messages Window is hidden, but displays automatically as a result of irregularities during Mechanical application operations. To display the window manually: select View>Windows>Messages. An example of the Messages Window is shown below.

In addition, the status bar provides a dedicated area (shown above) to alert you should one or more messages become available to view. The Messages Window can be auto-hidden or closed using the buttons on the top right corner of the window.

Note You can toggle between the Graph and Messages windows by clicking a tab. Once messages are displayed, you can: • Double-click a message to display its contents in a pop-up dialog box. • Highlight a message and then press the key combination Ctrl + C to copy its contents to the clipboard. • Press the Delete key to remove a selected message from the window. • Select one or more messages and then use the right mouse button click to display the following context menu options: – Go To Object - Selects the object in the tree which is responsible for the message. – Show Message - Displays the selected message in a popup dialog box. – Copy - Copies the selected messages to the clipboard. – Delete - Removes the selected messages.

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Application Interface – Refresh - Refreshes the contents of the Messages Window as you edit objects in the Mechanical application tree.

Graphics Annotation Window This window is displayed when you choose the User Defined Graphics Annotation button located on the Standard Toolbar. See the description of that button in the Standard Toolbar (p. 49) section for more information.

Section Planes Window The Section Plane window gives you access to the functionality for creating a cut or slice on your model so that you can view internal geometry, or mesh and results displays. For more information on this feature, see Creating Section Planes (p. 109).

Manage Views Window The Manage Views window gives you access to the functionality for saving graphical views and returning to a specific view at any time. For more information, see Managing Graphical View Settings (p. 107).

The Mechanical Wizard Window The Mechanical Wizard window appears in the right side panel whenever you click the Standard Toolbar (p. 49). See the The Mechanical Wizard (p. 123) section for details.

in the

Main Menus The main menus include the following items.

File Menu Edit Menu View Menu Units Menu Tools Menu Help Menu

File Menu Function

Description

Refresh All Data

Updates the geometry, materials, and any imported loads that are in the tree.

Save Project

Allows you to save the project.

Export

Allows you to export outside of the project. You can export a .mechdat file (when running the Mechanical application) that later can be imported into a new Workbench project. Note that only the data native to the Mechanical application is saved to the .mechdat file. External files (such as solver files) will not be exported. You can also export the mesh for input to any of the following: Fluent (.msh), Polyflow (.poly), CGNS (.cgns), and ICEM CFD (.prj).

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Main Menus Function

Description

Clear Generated Data

Clears all results and meshing data from the database depending on the object selected in the tree.

Close Mechanical

Exits the Mechanical application session.

Edit Menu Function

Description

Duplicate

Duplicates the object you highlight. The model and environment duplication is performed at the Project Schematic level (see Moving, Deleting, and Replacing Systems for details).

Duplicate Without Results

(Only available on solved result objects.) Duplicates the object you highlight, including all subordinate objects. Because the duplicated objects have no result data the process is faster than performing Duplicate.

Copy

Copies an object.

Cut

Cuts the object and saves it for pasting.

Paste

Pastes a cut or copied object.

Delete

Deletes the object you select.

Select All

Selects all items in the Model of the current selection filter type. Select All is also available in a context menu if you click the right mouse button in the Geometry window.

View Menu Function

Description

Shaded Exterior and Edges

Displays the model in the graphics window with shaded exteriors and distinct edges. This option is mutually exclusive with Shaded Exterior and Wireframe.

Shaded Exterior

Displays the model in the graphics window with shaded exteriors only. This option is mutually exclusive with Shaded Exterior and Edges and Wireframe. Displays the model in the Geometry window with a wireframe display rather than a shaded one (recommended for seeing gaps in surface bodies). This option is mutually exclusive with Shaded Exterior and Edges and Shaded Exterior. The Wireframe option not only applies to geometry, mesh, or named selections displayed as a mesh, but extends to probes, results, and variable loads to enable a better understanding of regions of interest.

Wireframe

When the View> Wireframe option is set, just the exterior faces of the meshed models are shown, not the interior elements. Note that when this option is on, green scoping is not drawn on probes. Also, elements are shown on probes and results, whereas the outline of the mesh is shown on isoline contour results. Selecting any of the edges options on contour results automatically closes Wireframe mode.

Graphics Options

Allows you to change the drawing options for edge connectivity. Most of these options are also available on the Edge Graphics Options toolbar. See the Edge Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Application Interface Function

Description Graphics Options (p. 71) section for additional details. This menu also provides the Draw Face Mode menu that allows you to change how faces are displayed as a function of back-face culling. Options include: • Auto Face Draw (default) - turning back-face culling on or off is program controlled. Using Section Planes is an example of when the application would turn this feature off. • Draw Front Faces - face culling is forced to stay on. Back-facing faces will not be drawn in any case, even if using Section Planes. • Draw Both Faces - back-face culling is turned off. Both front-facing and back-facing faces are drawn. See the Displaying Interior Mesh Faces section in the of the Help for a related discussion of how these options are used.

Cross Section Solids (Geometry)

Displays line body cross sections in 3D geometry. See Viewing Line Body Cross Sections (p. 388) for details.

Thick Shells and Beams

Toggles the visibility of the thickness applied to a shell or beam in the graphics window when the mesh is selected. See notes below.

Visual Expansion

Toggles the visibility of either a single cyclic sector mesh or the full symmetry mesh in a cyclic symmetry analysis. Toggling this option can help preview before solving the density of nodes on the sector boundaries, or it can help confirm the expanded mesh in each case.

Annotation PreferDisplays the Annotation Preferences dialog box. ences Annotations

Toggles the visibility of annotations in the graphics window.

Ruler

Toggles the visibility of the visual scale ruler in the graphics window.

Legend

Toggles the visibility of the results legend in the graphics window.

Triad

Toggles the visibility of the axis triad in the graphics window.

Eroded Nodes

Toggles the visibility of eroded nodes for explicit dynamics analyses.

Large Vertex Contours

Used in mesh node result scoping to toggle the size of the displayed dots that represent the results at the underlying mesh nodes.

Display Edge Direction

Displays model edge directions. The direction arrow appears at the midpoint of the edge. The size of the arrow is proportional to the edge length. Expand All - Restores tree objects to their original expanded state.

Outline

Collapse Environments - Collapses all tree objects under the Environment object(s). Collapse Models - Collapses all tree objects under the Model object(s). Named Selections - Displays the Named Selection Toolbar (p. 69). Unit Conversion - Displays the Unit Conversion Toolbar (p. 69).

Toolbars

Graphics Options - Displays the Graphics Options Toolbar (p. 69). Edge Graphics Options - Displays the Edge Graphics Options (p. 71). Tree Filter - Displays the Tree Filter Toolbar (p. 73). Joint Configure - Displays the Joint Configure Context Toolbar (p. 57).

Windows

Messages - Toggles the display of the Messages window.

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Main Menus Function

Description Mechanical Wizard - Toggles the display of a wizard on the right side of the window which prompts you to complete tasks required for an analysis. Graphics Annotations - Toggles the display of the Annotations window. Section Planes - Toggles the display of the Section Planes window. Selection Information - Toggles the display of the Selection Information window. Manage Views - Toggles the display of the Manage Views window. Tags - Toggles the display of the Tags window. Reset Layout - Restores the Window layout back to a default state.

Notes: • Displaying Shells for Large Deflections: The display of shells may become distorted for large deformations such as in large deflection or during an Explicit Dynamics analyses. A workaround for this is to disable Shell Thickness by toggling View>Thick Shells and Beams. Or, set a Workbench variable, UsePseudoShellDisp = 1, through Tools> Variable Manager. It may be necessary to toggle the deformation scaling from True Scale to Undeformed to True Scale again (see Scaling Deformed Shape in the Context Toolbar Section). Note that this option requires True Scaling to work properly. • Displaying Shells on Shared Entities: The display of shells is done on a nodal basis. Therefore, graphics plot only 1 thickness per node, although node thickness can be prescribed and solved on a per elemental basis. When viewing shell thickness at sharp face intersections or a shared body boundary, the graphics display may become distorted. • Displaying Contours and Displaced Shapes on Line Bodies: The contour result on a line body are expanded to be viewed on the cross section shape, but only one actual result exists at any given node and as a result no contour variations across a beam section occur. • Display Pipes using Pipe Idealizations: Although the solution will account for cross section distortions, the graphics rendering for the results display the cross sections in their original shape.

Units Menu Function

Description

Metric (m, kg, N, s, V, A)

Sets unit system.

Metric (cm, g, dyne, s, V, A) Metric (mm, kg, N, s, mV, mA) Metric (mm, t, N, s, mV, mA) Metric (mm, dat, N, s, mV, mA) Metric (µm, kg, µN, s, V, mA) U.S. Customary (ft, lbm, lbf, °F, s, V, A) U.S. Customary (in, lbm, lbf, °F, s, V, A) Degrees

Sets angle units to degrees.

Radians

Set angle units to radians.

rad/s

Sets angular velocity units to radians per second.

RPM

Sets angular velocity units to revolutions per minute.

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Application Interface Function

Description

Celsius

Sets the temperature values to degree Celsius (not available if you choose either of the U.S. Customary settings).

Kelvin

Sets the temperature values to Kelvin (not available if you choose either of the U.S. Customary settings).

Tools Menu Function

Description

Write Input File...

Writes the Mechanical APDL application input file from the active Solution branch. This option does not initiate a Solve.

Read Result File...

Reads the Mechanical APDL application result files (.rst, solve.out, and so on) in a directory and copies the files into the active Solution branch.

Solve Process Settings

Allows you to configure solve process settings.

Addins...

Launches the Addins manager dialog that allows you to load/unload third-party add-ins that are specifically designed for integration within the Workbench environment.

Options...

Allows you to customize the application and to control the behavior of Mechanical application functions.

Variable Manager

Allows you to enter an application variable.

Run Macro...

Opens a dialog box to locate a script (.vbs , .js ) file.

Help Menu Function

Description

Mechanical Help

Displays the Help system in another browser window.

About Mechanical

Provides copyright and application version information.

Note View menu settings are maintained between Mechanical application sessions except for the Outline items and Reset Layout in the Windows submenu.

Toolbars Toolbars are displayed across the top of the window, below the menu bar. Toolbars can be docked to your preference. The layouts displayed are typical. You can double-click the vertical bar in the toolbar to automatically move the toolbar to the left. The various toolbars are described in the following sections: Standard Toolbar Graphics Toolbar Context Toolbar Named Selection Toolbar Unit Conversion Toolbar Graphics Options Toolbar

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Toolbars Edge Graphics Options Tree Filter Toolbar

Standard Toolbar

The Standard Toolbar contains application-level commands, configuration toggles and important general functions. Each icon button and its description follows: Icon Button

Application-level command

Description

View Mechanical Wizard

Activates the Mechanical Wizard in the user interface.

View Object Generator

Activates the Object Generator window in the user interface.

Solve analysis with a given solve process setting.

Drop-down list to select a solve process setting.

Show Errors

Displays error messages associated with tree objects that are not properly defined.

New Section Plane

View a section cut through the model (geometry, mesh and results displays) as well as obtained capped displays on either side of the section. Refer to the Creating Section Planes (p. 109) section for details.

User Defined Graphics Annotation

Adds a text comment for a particular item in the Geometry window. To use: • Select button in toolbar. • Click a placement location on the geometry. A chisel-shaped annotation is anchored in 3D. • A blank annotation appears and the Graphics Annotation window is made visible or brought forward. • A new row is created for the annotation. • Type entry. To edit, double click the corresponding entry in the Graphics Annotation window and type new information. To delete, select the entry and press the delete key. To move, select the annotation in the geometry window and move while pressing down the left mouse button. To exit without creating an annotation, re-click the annotation button.

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Application Interface Icon Button

Application-level command

Description

New Chart and Table

Refer to the Chart and Table (p. 988) section for details.

New Simplorer Pin

For Rigid Dynamic analyses, Simplorer Pins are used to define/describe interface points between a Simplorer model and the joints of the Rigid Dynamics model.

New Comment

Adds a comment within the currently highlighted outline branch.

New Figure

Captures any graphic displayed for a particular object in the Geometry window.

New Image

Adds an image within the currently highlighted outline branch.

Image from File

Imports an existing graphics image.

Image to File

Saves the current graphics image to a file (.png, .jpg, .tif, .bmp, .eps).

Note The Aero Theme display mode in Windows 7 is incompatible with the screen capture used in Mechanical. If you are running Windows 7, select a Basic Theme display mode to restore this capability. Show/Hide Worksheet Window

Enables Worksheet window to be displayed for specific objects.

Selection Information

Activates the Selection Information Window (p. 25).

Graphics Toolbar The Graphics Toolbar sets the selection/manipulation mode for the cursor in the graphics window. The toolbar also provides commands for modifying a selection or for modifying the viewpoint. Each icon button and its description follows: Icon Button

Tool Tip Name Displayed Label

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Description Allows you to move and place the label of a load anywhere along the feature that the load is currently scoped to.

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Toolbars Icon Button

Tool Tip Name Displayed

Description

Direction

Chooses a direction by selecting either a single face, two vertices, or a single edge (enabled only when Direction field in the Details view has focus). See Pointer Modes.

Hit Point Coordinate

(Active only if you are setting a location, for example, a local coordinate system.) Enables the exterior coordinates of the model to display adjacent to the cursor and updates the coordinate display as the cursor is moved across the model. If you click with the cursor on the model, a label displays the coordinates of that location. This feature is functional on faces only. It is not functional on edges or line bodies.

Select Type

• Select Geometry: This option allows you to select geometric entities (bodies, faces, edges, and vertices). • Select Mesh: This option allows you to select nodes or a group of nodes by picking the node or nodes graphically or by defining a node or group of nodes as a Named Selection. Note that you must first generate the mesh.

Select Mode

Defines how geometry or node selections are made: • Single Select • Box Select • Box Volume Select • Lasso Select • Lasso Volume Select These options are used in conjunction with the selection filters (Vertex, Edge, Face, Body)

Note Selection shortcuts: • You can change your selection mode from Single Select to Box Select by holding the right mouse button and then clicking the left mouse button. • Given a generated mesh and that the Mesh Select option is active, holding the right mouse button and then clicking the left mouse button scrolls through the available selection options (single section, box selection, box volume, lasso, lasso volume).

Vertex

Designates vertex or node only for picking or viewing selection.

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Application Interface Icon Button

Tool Tip Name Displayed

Description

Edge

Designates edges only for picking or viewing selection.

Face

Designates faces only for picking or viewing selection.

Body

Designates bodies only for picking or viewing selection.

Extend Selection

Adds adjacent faces (or edges) within angle tolerance, to the currently selected face (or edge) set, or adds tangent faces (or edges) within angle tolerance, to the currently selected face (or edge) set.

Rotate

Activates rotational controls based on the positioning of the mouse cursor.

Pan

Moves display model in the direction of the mouse cursor.

Zoom

Displays a closer view of the body by dragging the mouse cursor vertically toward the top of the graphics window, or displays a more distant view of the body by dragging the mouse cursor vertically toward the bottom of the graphics window.

Box Zoom

Displays selected area of a model in a box that you define.

Fit

Fits the entire model in the graphics window.

Toggle Magnifier Window On/Off

Displays a Magnifier Window, which is a shaded box that functions as a magnifying glass, enabling you to zoom in on portions of the model. When you toggle the Magnifier Window on, you can: • Pan the Magnifier Window across the model by holding down the left mouse button and dragging the mouse. • Increase the zoom of the Magnifier Window by adjusting the mouse wheel, or by holding down the middle mouse button and dragging the mouse upward. • Recenter or resize the Magnifier Window using a right mouse button click and choosing an option from the context menu. Recenter the window by choosing Reset Magnifier. Resizing options include Small Magnifier, Medium Magnifier, and Large Magnifier for preset sizes, and Dynamic Magnifier Size On/Off for gradual size control accomplished by adjusting the mouse wheel. Standard model zooming, rotating, and picking are disabled when you use the Magnifier Window.

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Previous View

To return to the last view displayed in the graphics window, click the Previous View button on the toolbar. By continuously clicking you can see the previous views in consecutive order.

Next View

After displaying previous views in the graphics window, click the Next View button on the toolbar to scroll forward to the original view.

Set (ISO)

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Toolbars Icon Button

Tool Tip Name Displayed

Description (arbitrary rotation), or define the "up" direction so that geometry appears upright.

Look at

Centers the display on the currently selected face or plane.

Manage Views

Displays the Manage Views window, which you can use to save graphical views.

Rescale Annotation

Adjusts the size of annotation symbols, such as load direction arrows.

Tags

Displays the Tags window, where you can mark objects in the tree with meaningful labels, which can then be used to filter the tree.

Viewports

Splits the graphics display into a maximum of four simultaneous views.

Keyboard Support The same functionality is available via your keyboard provided the NumLock key is enabled. The numbers correlate to the following functionality: 0 = View Isometric 1 = +Z Front 2 = -Y Bottom 3 =+X Right 4 = Previous View 5 = Default Isometric 6 = Next View 7 = -X Left 8 = +Y Top 9 = -Z Back . (dot) = Set Isometric

Context Toolbar The Context Toolbar configures its buttons based on the type of object selected in the Tree Outline (p. 3). The Context Toolbar makes a limited number of relevant choices more visible and readily accessible. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Application Interface Context Toolbars include: • Model Context Toolbar (p. 55) • Geometry Context Toolbar (p. 56) • Virtual Topology Context Toolbar (p. 56) • Symmetry Context Toolbar (p. 56) • Connections Context Toolbar (p. 57) • Joint Configure Context Toolbar (p. 57) • Coordinate System Context Toolbar (p. 57) • Meshing Context Toolbar (p. 58) • Fracture Context Toolbar (p. 58) • Gap Tool Context Toolbar (p. 58) • Environment Context Toolbar (p. 58) • Variable Data Toolbar (p. 59) • Solution Context Toolbar (p. 59) • Solution Information Toolbar (p. 59) • Vector Display Context Toolbar (p. 64) • Result Context Toolbar (p. 59) • Geometry (p. 62) • Comment Context Toolbar (p. 68) • Print Preview Context Toolbar (p. 69) • Report Preview Context Toolbar (p. 69)

Note • Some Context Toolbar items, such as Connections or Mesh Controls, can be hidden. • Some Context Toolbar items cannot be hidden (for simplicity and to avoid jumbling the screen). The toolbar appears blank when no options are relevant. • The toolbar displays a text label for the current set of options. • A Workbench Options dialog box setting turns off button text labels to minimize context toolbar width.

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Toolbars

Model Context Toolbar

The Model Context toolbar becomes active when the Model object is selected in the tree. The Model Context toolbar contains options for creating objects related to the model, as described below. Construction Geometry See the Path (Construction Geometry) (p. 453) and Surface (Construction Geometry) (p. 459) sections for details. Virtual Topology You can use the Virtual Topology option to reduce the number of elements in a model by merging faces and lines. This is particularly helpful when small faces and lines are involved. The merging will impact meshing and selection for loads and supports. See Virtual Topology Overview for details. Symmetry For symmetric bodies, you can remove the redundant portions based on the inherent symmetry, and replace them with symmetry planes. Boundary conditions are automatically included based on the type of analyses. Remote Point See the Remote Point (p. 460) section for details. Connections The Connections button is available only if a connection object is not already in the tree (such as a model that is not an assembly), and you wish to create a connections object. Connection objects include contact regions, joints, and springs. You can transfer structural loads and heat flows across the contact boundaries and “connect” the various parts. See the Contact section for details. A joint typically serves as a junction where bodies are joined together. Joint types are characterized by their rotational and translational degrees of freedom as being fixed or free. See the Joints section for details. You can define a spring (longitudinal or torsional) to connect two bodies together or to connect a body to ground. See the Springs section for details. Mesh Numbering The Mesh Numbering feature allows you to renumber the node and element numbers of a generated meshed model consisting of flexible parts. See the Mesh Numbering (p. 451) section for details. Solution Combination Use the Solution Combination option to combine multiple environments and solutions to form a new solution. A solution combination folder can be used to linearly combine the results from an arbitrary number of load cases (environments). Note that the analysis environments must be static structural with no solution convergence. Results such as stress, elastic strain, displacement, contact, and fatigue may be requested. To add a load case to the solution combination folder, right click on the worksheet view of the solution combination folder, choose add, and then select the scale factor and the environment name. An environment may be added more than once and its effects will be cumulative. You may suppress the effect of a load case by using the check box in the worksheet view or by deleting it through a right click. For more information, see Solution Combinations (p. 1019).

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Application Interface Named Selection You can create named selections to specify and control like-grouped items such as types of geometry. For more information, see Named Selections (p. 429).

Geometry Context Toolbar

The Geometry Context toolbar is active when you select the Geometry branch in the tree or any items within the Geometry branch. If you are using an assembly meshing algorithm, you can use the Geometry toolbar to insert a virtual body. Using the Geometry toolbar you can also apply a Point Mass or a Thermal Point Mass. You can also add a Commands object to individual bodies. For surface bodies, you can add a Thickness object or an Imported Thickness object to define variable thickness, or Layered Section objects to define layers applied to surfaces.

Construction Geometry

See Path (Construction Geometry) (p. 453) and Surface (Construction Geometry) (p. 459) for details.

Virtual Topology Context Toolbar The Virtual Topology Context toolbar includes the following controls: • Merge Cells button: For creating Virtual Cell objects in which you can group faces or edges. • Split Edge at + and Split Edge buttons: For creating Virtual Split Edge objects, which allow you to split an edge to create two virtual edges. • Split Face at Vertices button: For creating Virtual Split Face objects, which allow you to split a face along two vertices to create 1 to N virtual faces. The selected vertices must be located on the face that you want to split. • Hard Vertex at + button: For creating Virtual Hard Vertex objects, which allow you to define a hard point according to your cursor location on a face, and then use that hard point in a split face operation. •

and buttons: For cycling through virtual topology entities in the sequence in which they were created. If any virtual topologies are deleted or merged, the sequence is adjusted automatically. See Cycling Through Virtual Entities in the Geometry Window.

• Edit button: For editing virtual topology entities. • Delete button: For deleting selected virtual topology entities, along with any dependents if applicable.

Symmetry Context Toolbar The Symmetry Context toolbar includes an option to insert Symmetry Region, Periodic Region, or Cyclic Region objects where you can define symmetry planes.

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Toolbars

Connections Context Toolbar The Connections context toolbar includes the following settings and functions: • Connection Group button: Inserts a Connection Group object. • Contact drop down menu: Inserts one of the following: a manual Contact Region object set to a specific contact type, a Contact Tool object (for evaluating initial contact conditions), or a Solution Information object. • Spot Weld button: Inserts a Spot Weld object. • Mesh Connection button: Inserts a Mesh Connection object. • End Release button: Inserts an End Release object. • Body Interactions See Body Interactions in Explicit Dynamics Analyses (p. 619) for details. • Body-Ground drop-down menu: Inserts a type of Joint object, Spring object, or a Beam object, whose reference side is fixed. • Body-Body drop-down menu: Inserts a type of Joint object, Spring object, or a Beam object, where neither side is fixed. • Body Views toggle button: For joints, Mesh Connections, and Contacts, displays parts and connections in separate auxiliary windows. • Sync Views toggle button: When the Body Views button is engaged, any manipulation of the model in the Geometry window will also be reflected in both auxiliary windows. • Commands icon button: Inserts a Commands object.

Joint Configure Context Toolbar

The Joint Configure context toolbar includes the following settings and functions: • Configure, Set, and Revert buttons; and ∆ = field: Graphically configures the initial positioning of a joint. Refer to Example: Configuring Joints (p. 576) for details. • Assemble button: For joints, performs the assembly of the model, finding the closest part configuration that satisfies all the joints. This toolbar only displays when you have a Joint selected. It can be displayed manually by selecting View>Toolbars>Joint Configure.

Coordinate System Context Toolbar

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Application Interface The Coordinate System context toolbar includes the following options: • Create Coordinate System: use the Create Coordinate System button ( a coordinate system.

) on the toolbar to create

• Transform the coordinate system using one of the following features: – Translation: Offset X, Offset Y, or Offset Z. – Rotation: Rotate X, Rotate Y, or Rotate Z. – Flip: Flip X, Flip Y, or Flip Z. – Move Up and Move Down: scroll up or down through the Transformation category properties. – Delete: delete Transformation category properties.

Meshing Context Toolbar

The Meshing Context toolbar includes the following controls: • Update button - for updating a cell that references the current mesh. This will include mesh generation as well as generating any required outputs. • Mesh drop down menu - for implementing meshing ease of use features. • Mesh Control drop down menu - for adding Mesh Controls to your model. • Metric Graph button - for hiding and showing the Mesh Metrics bar graph.

Fracture Context Toolbar

The Fracture Context toolbar allows you to apply the objects associated with a Fracture Analysis, including Cracks as well as progressive failure features in the form of Interface Delamination and Contact Debonding objects.

Gap Tool Context Toolbar

The Gap Tool Context toolbar is used to have the Mechanical application search for face pairs within a specified gap distance that you specify.

Environment Context Toolbar

The Environment Context toolbar allows you to apply loads to your model. The toolbar display varies depending on the type of simulation you choose. For example, the toolbar for a Static Structural analysis is shown above.

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Toolbars

Variable Data Toolbar

The Variable Data toolbar allows you to view contours or the isoline representation of variable data, including spatial varying loads, imported loads, and thicknesses. You can also view the variable data as an isoline.

Note • The isoline option is drawn based on nodal values. When drawing isolines for imported loads that store element values (Imported Body Force Density, Imported Convection, Imported Heat Generation, Imported Heat Flux, Imported Pressure, and Imported Surface Force Density), the program automatically calculates nodal values by averaging values of the elements to which a node is attached. • This toolbar is not available for Imported Loads that are scoped to nodal-based Named Selections.

Solution Context Toolbar

The Solution toolbar applies to Solution level objects that either: • Never display contoured results (such as the Solution object), or • Have not yet been solved (no contours to display). The options displayed on this toolbar are based on the type of analysis that is selected. The example shown above displays the solution options for a static structural analysis. Objects created via the Solution toolbar are automatically selected in the Outline. Prior to a solution this toolbar always remains in place (no contours to display). A table in the Applying Results Based on Geometry (p. 858) section indicates which bodies can be represented by the various choices available in the drop-down menus of the Solution toolbar.

Solution Information Toolbar

Selecting the Solution Information object displays a corresponding toolbar. It’s options include the Result Tracker drop-down menu and the Retrieve button. The Retrieve feature allows you to track background solutions.

Result Context Toolbar

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Application Interface The Result toolbar applies to Solution level objects that display contour or vector results. The following subsections describe the options available on this toolbar. • Scaling Deformed Shape (p. 60) • Relative Scaling (p. 61) • Geometry (p. 62) • Contours Options (p. 62) • Edges Options (p. 63) • Vector Display Context Toolbar (p. 64) • Max, Min, and Probe Annotations (p. 66) • Display (p. 66)

Scaling Deformed Shape For results with an associated deformed shape, the Scaling combo box provides control over the onscreen scaling:

Scale factors precede the descriptions in parentheses in the list. The scale factors shown above apply to a particular model's deformation and are intended only as an example. Scale factors vary depending on the amount of deformation in the model. You can choose a preset option from the list or you can type a customized scale factor relative to the scale factors in the list. For example, based on the preset list shown above, typing a customized scale factor of 0.6 would equate to approximately 3 times the Auto Scale factor. • Undeformed does not change the shape of the part or assembly. • True Scale is the actual scale. • Auto Scale scales the deformation so that it's visible but not distorting. • The remaining options provide a wide range of scaling. The system maintains the selected option as a global setting like other options in the Result toolbar. As with other presentation settings, figures override the selection.

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Toolbars For results that are not scaled, the combo box has no effect.

Note Most of the time, a scale factor will be program chosen to create a deformed shape that will show a visible deflection to allow you to better observe the nature of the results. However, under certain conditions, the True Scale displaced shape (scale factor = 1) is more appropriate and is therefore the default if any of the following conditions are true: • Rigid bodies exist. • A user-defined spring exists in the model. • Large deflection is on. This applies to all analyses except for modal and linear buckling analyses (in which case True Scale has no meaning). Currently, if you are performing a Modal or Linear Buckling analysis that includes rigid body parts, the application is experiencing a limitation while scaling and/or animating results. The motion of rigid parts is subject to changes in the position of the center of mass (linear displacement) and changes in rotation (angular displacements). Because linear displacement and angular displacement are different concepts, a scaling (other than True) that satisfies both (and one which is calculated quickly) has not yet been implemented. Therefore, True scale is the best setting when animating rigid parts. For the best scaling results when working on a Modal analysis (where displacements are not true), use the Auto Scale option. However, when you have multiple scaling options selected, such as a body whose optimal scaling is True and another body whose optimal scaling is Auto Scale, then the graphical display of the motion of the bodies does not appear cleanly. For random vibration (PSD) and response spectrum analyses, Mechanical sets the scale factor to zero. In this case, the image of the finite element model does not deform.

Relative Scaling The combo list provides five "relative" scaling options. These options scale deformation automatically relative to preset criteria: • Undeformed • True Scale • 0.5x Auto • Auto Scale • 2x Auto • 5x Auto

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Application Interface

Geometry You can observe different views from the Geometry drop-down menu.

• Exterior This view displays the exterior results of the selected geometry. • IsoSurfaces This view displays the interior only of the model at the transition point between values in the legend, as indicated by the color bands. • Capped IsoSurfaces This view displays contours on the interior and exterior. When you choose Capped IsoSurfaces, a Capped Isosurface toolbar appears beneath the Result context toolbar. Refer to Capped Isosurfaces for a description of the controls included in the toolbar. • Section Planes This view displays planes cutting through the result geometry; only previously drawn Section Planes are visible. The model image changes to a wireframe representation.

Contours Options To change the way you view your results, click any of the options on this toolbar.

• Smooth This view displays gradual distinction of colors. • Contour This view displays the distinct differentiation of colors. • Isolines This view displays a line at the transition between values. 62

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Toolbars • Solid This view displays the model only with no contour markings.

Edges Options You can switch to wireframe mode to see gaps in surface body models. Red lines indicate shared edges. In addition, you can choose to view wireframe edges, include the deformed model against the undeformed model, or view elements. Showing a subdued view of the undeformed model along with the deformed view is especially useful if you want to view results on the interior of a body yet still want to view the rest of the body's shape as a reference. An example is shown here.

The Show Undeformed Model option is useful when viewing any of the options in the Geometry dropdown menu.

• No Wireframe This view displays a basic picture of the body. • Show Undeformed Wireframe This view shows the body outline before deformation occurred. If the Creating Section Planes (p. 109) feature is active, choosing Show Undeformed WireFrame actually displays the wireframe with the deformations added to the nodes. This is intended to help you interpret the image when you drag the section plane anchor across smaller portions of the model. • Show Undeformed Model This view shows the deformed body with contours, with the undeformed body in translucent form. • Show Elements This view displays element outlines.

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Application Interface

Vector Display Context Toolbar Using the Graphics button, you can display results as vectors with various options for controlling the display.

• Click the Graphics button on the Result context toolbar to convert the result display from contours (default) to vectors. • When in vector display, a Vector Display toolbar appears with controls as described below.

Displays vector length proportional to the magnitude of the result. Displays a uniform vector length, useful for identifying vector paths. Controls the relative length of the vectors in incremental steps from 1 to 10 (default = 5), as displayed in the tool tip when you drag the mouse cursor on the slider handle. Displays all vectors, aligned with each element. Displays vectors, aligned on an approximate grid. Controls the relative size of the grid, which determines the quantity (density) of the vectors. The control is in uniform steps from 0 [coarse] to 100 [fine] (default = 20), as displayed in the tool tip when you drag the mouse cursor on the slider handle.

Note This slider control is active only when the adjacent button is chosen for displaying vectors that are aligned with a grid. Displays vector arrows in line form. Displays vector arrows in solid form.

• When in vector display, click the Graphics button on the Result context toolbar to change the result display back to contours. The Vector Display toolbar is removed. Presented below are examples of vector result displays.

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Toolbars

Uniform vector lengths identify paths using vector arrows in line form.

Course grid size with vector arrows in solid form.

Same using wireframe edge option.

Uniform vector lengths , grid display on section plane with vector arrows in solid form.

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Application Interface

Zoomed-in uniform vector lengths , grid display with arrow scaling and vector arrows in solid form.

Max, Min, and Probe Annotations

Toolbar buttons allow for toggling Max and Min annotations and for creating probe annotations. See also Viewing Annotations (p. 114).

Display

The Display feature on the Result Context Toolbar allows you to view: • All Bodies - Regions of the model not being drawn as a contour are plotted as translucent even for unscoped bodies as long as the bodies are visible (not hidden).

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Toolbars

• Scoped Bodies - (default setting) Regions of the model not being drawn as a contour are plotted as translucent for scoped bodies only. Unscoped bodies are not drawn.

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Application Interface • Results Only - Only the resultant contour or vector is displayed.

Limitations The following limitations apply to this feature: • The Scoped Bodies and Results Only options support geometry-based scoping (Geometry Selection property = Geometry) and Named Selections that are based on geometry selections or worksheet criteria. • The Scoped Bodies and Results Only options do not support Construction Geometry features Path and Surface. • The Results Only option does not support the Explicit Dynamics Solver (AUTODYN). • For the Scoped Bodies option for results that are scoped across multiple entities (vertices, edges, faces, or volumes), all of these entities may not display because there are times when only the nodes of one of the shared entities are used in the calculation.

Comment Context Toolbar

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Toolbars When you select the Comment button in the standard toolbar or when you select a Comment object already in the tree, the Comment Context toolbar and Comment Editor appear. The buttons at the top allow you to insert an image or apply various text formatting. To insert an image, click the button whose tool tip is Insert Image, then complete the information that appears in the dialog box. For the Image URL, you can use a local machine reference (C:\...) or a web reference (http:\\...).

Print Preview Context Toolbar

The Print Preview toolbar allows you to print the currently-displayed image, or send it to an e-mail recipient or to a Microsoft Word or PowerPoint file.

Report Preview Context Toolbar The Report Preview toolbar allows you to send the report to an e-mail recipient or to a Microsoft Word or PowerPoint file, print the report, save it to a file, or adjust the font size.

Named Selection Toolbar The Named Selection toolbar allows you to select, add to, and remove items from existing user-defined named selections as well as modify the visibility and suppression states. The specific features available on the toolbar are described in the Using Named Selections via the Toolbar (p. 446) section.

Unit Conversion Toolbar The Unit Conversion toolbar is a built-in conversion calculator. It allows conversion between consistent unit systems. The Units menu sets the active unit system. The status bar shows the current unit system. The units listed in the toolbar and in the Details view are in the proper form (i.e. no parenthesis). The Unit Conversions toolbar is hidden by default. To see it, select View> Toolbars> Unit Conversion.

Graphics Options Toolbar

The Graphics Options toolbar provides quick access to features that are useful for controlling the graphical display of models. The toolbar is displayed by default, but can be hidden (or turned back on) by selecting View> Toolbars> Graphics Options. Refer to the table below for the specific actions you can take using this toolbar’s features.

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Application Interface Icon Button

Tool Tip Name Displayed

Description

Toggle Show Vertices On or Off

Enabling the Show Vertices button highlights all vertices on the model. This feature is especially useful when examining complex assemblies where vertices might normally be hidden from view. It can also be used to ensure that edges are complete and not segmented unintentionally. Enabling Wireframe mode displays the model in the Geometry window with a wireframe display rather than a shaded one (recommended for seeing gaps in surface bodies). The Wireframe option not only applies to geometry, mesh, or named selections displayed as a mesh, but extends to probes, results, and variable loads to enable a better understanding of regions of interest.

Wireframe Mode On or Off

When Wireframe mode is set, just the exterior faces of the meshed models are shown, not the interior elements. Note that when this option is on, green scoping is not drawn on probes. Also, elements are shown on probes and results, whereas the outline of the mesh is shown on isoline contour results. Selecting any of the edges options on contour results automatically closes Wireframe mode.

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Show Mesh

Enabling the Show Mesh button displays the model’s mesh regardless of the selected tree object. When enabled, to make sure that Annotations display properly, also turn on Wireframe mode. See Note below.

Show all Coordinate Systems

Enabling the Show all Coordinate Systems button displays all available coordinate systems associated with the model – default as well as user defined.

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Toolbars Icon Button

Tool Tip Name Displayed

Description

Random Colors

By default, all loads, supports, named selections, and contacts are shown in one color. Enabling the Random Colors button displays each distinct load, support, named selection, or contact with a random color at each redraw.

Annotation Preferences

Displays the Annotation Preferences dialog box, in which you set preferences for annotation display.

Note As illustrated below, annotations may not always display properly when the Show Mesh button is activated. Turning on Wireframe mode accurately displays Annotations when Show Mesh is selected.

Edge Graphics Options

The Edge Graphics Options toolbar is a graphical display feature used for displaying the edges on a model; their connectivity and how they are shared by faces. The toolbar is displayed by default, but can be hidden (or turned back on) by selecting View>Toolbars>Edge Graphics Options. Refer to the table below for the specific actions you can take using this toolbar’s features. Also see the Assemblies of Surface Bodies (p. 376) section for details. Icon Button

Tool Tip Name Displayed

Description By Body Color: Displays body colors to represent boundary edges.

Edge Coloring

By Connection: Displays five different colors corresponding to five different categories of connectivity. The categories are: free (blue), single (red), double (black), triple (pink) and multiple (yellow). Free means that the edge is not shared by any faces. Single means that the edge is shared by one face and so on. The color scheme is also displayed in the Edge/Face Connectivity legend.

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Application Interface Icon Button

Tool Tip Name Displayed

Description Black: Turns off the edge/face connectivity display. The entire model is displayed in black. Hide Free: Hides only edges not shared by any faces.

Free

Show Free: Displays only edges not shared by any faces. Thick Free: Displays only edges not shared by any faces at a different edge thickness compared to the rest of the model. Hide Single: Hides only edges that are shared by one face.

Single

Show Single: Displays only that are shared by one face. Thick Single: Displays only edges that are shared by one face at a different edge thickness compared to the rest of the model. Hide Double: Hides only edges that are shared by two faces.

Double

Show Double: Displays only that are shared by two faces. Thick Double: Displays only edges that are shared by two faces at a different edge thickness compared to the rest of the model. Hide Triple: Hides only edges that are shared by three faces.

Triple

Show Triple: Displays only that are shared by three faces. Thick Triple: Displays only edges that are shared by three faces at a different edge thickness compared to the rest of the model. Hide Multiple: Hides only edges that are shared by more than three faces.

Multiple

Edge Direction

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Show Multiple: Displays only that are shared by more than three faces. Thick Multiple: Displays only edges that are shared by more than three faces at a different edge thickness compared to the rest of the model. Displays model edge directions. The direction arrow appears at the midpoint of the edge. The size of

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Interface Behavior Based on License Levels Icon Button

Tool Tip Name Displayed

Description the arrow is proportional to the edge length.

Edges Joined by Mesh Connection

Display the edges using coloring schema, by taking into account the mesh connection information.

For annotations scoped to lines (for example, annotations representing loads, Thicken annotations scoped named selections, point masses, and so to lines on), enabling this button thickens these lines so they are more easily identifiable on the screen.

Note The following restrictions apply when using the Edge Graphics Options functions on the mesh, as compared to their use on geometry: • Not all the buttons/options are functional, for example, Double always displays thin black lines. The width of the colored lines cannot be changed. They are always thick. • During slicing, the colors of shared element edges are not drawn. They display as black and appear only when the selected section plane is losing focus in the slice tool pane.

Tree Filter Toolbar The Tree Filter toolbar is used to filter the tree for objects or tags matching specified search terms For information on using this toolbar, see Filtering the Tree (p. 9). The Tree Filter toolbar is shown by default. To hide it, select View> Toolbars> Tree Filter. Mechanical will restore your last setting with each new session.

Interface Behavior Based on License Levels The licensing level that you choose automatically allows you to exercise specific features and blocks other features that are not allowed. Presented below are descriptions of how the interface behaves when you attempt to use features not allowed by a license level. • If the licensing level does not allow an object to be inserted, it will not show in the Insert menus. • If you open a database with an object that does not fit the current license level, the database changes to "read-only" mode. • If a Details view option is not allowed for the current license level, it is not shown.

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Application Interface • If a Details view option is not allowed for the current license level, and was preselected (either through reopening of a database or a previous combination of settings) the Details view item will become invalid and shaded yellow.

Note When you attempt to add objects that are not compatible with your current license level, the database enters a read-only mode and you cannot save data. However, provided you are using any license, you can delete the incompatible objects, which removes the read-only mode and allows you to save data and edit the database.

Environment Filtering The Mechanical interface includes a filtering feature that only displays model-level items applicable to the particular analysis type environments in which you are working. This provides a simpler and more focused interface. The environment filter has the following characteristics: • Model-level objects in the tree that are not applicable to the environments under a particular model are hidden. • The user interface inhibits the insertion of model-level objects that are not applicable to the environments of the model. • Model-level object properties (in the Details view of objects) that are not applicable to the environments under the model are hidden. The filter is enabled by default when you enter the Mechanical application. You can disable the filter by highlighting the Model object, clicking the right mouse button, and choosing Disable Filter from the context menu. To enable the filter, repeat this procedure but choose Auto Filter from the context menu. You can also check the status of the filter by highlighting the Model object and in the Details view, noting whether Control under Filter Options is set to Enabled or Disabled. The filter control setting (enabled or disabled) is saved when the model is saved and returns to the same state when the database is resumed.

Customizing the Mechanical Application Specifying Options (p. 74) Setting Variables (p. 85) Using Macros (p. 86)

Specifying Options You can control the behavior of functions in the Mechanical application through the Options dialog box. To access the Mechanical application options: 1. From the main menu, choose Tools> Options. An Options dialog box appears and the Mechanical application options are displayed on the left. 2. Click on a specific option.

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Customizing the Mechanical Application 3. Change any of the option settings by clicking directly in the option field on the right. You will first see a visual indication for the kind of interaction required in the field (examples are drop-down menus, secondary dialog boxes, direct text entries). 4. Click OK.

Note • If you enter a number with the thousand separator (in English, the thousand separator is a comma [,]), you will be asked to confirm the entry before it is accepted. For example, if you enter “2,300”, you receive a message stating the following: “Entered value is 2,300. Do you want to accept the correction proposed below? 2300 To accept the correction, click Yes. To close this message and correct the number yourself, click No. • Option settings within a particular language are independent of option settings in another language. If you change any options from their default settings, then start a new Workbench session in a different language, the changes you made in the original language session are not reflected in the new session. You are advised to make the same option changes in the new language session.

Mechanical Options The following Mechanical application options appear in the Options dialog box: Connections Convergence Import Export Fatigue Frequency Geometry Graphics Miscellaneous Report Analysis Settings and Solution Visibility Wizard

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Application Interface

Connections The Auto Detection category allows you to change the default values in the Details view for the following:

Note The auto contact detection on geometry attach can be turned on/off from the Workbench Options dialog box for the Mechanical application. See the Mechanical part of the Setting ANSYS Workbench Options section of the Help. • Tolerance: Sets the default for the contact detection slider; i.e., the relative distance to search for contact between parts. The higher the number, the tighter the tolerance. In general, creating contacts at a tolerance of 100 finds less contact surfaces than at 0. The default is 0. The range is from -100 to +100. • Face/Face: Sets the default preference1 (p. 76) for automatic contact detection between faces of different parts. The choices are Yes or No. The default is Yes. • Face/Edge: Sets the default preference1 (p. 76) for automatic contact detection between faces and edges of different parts. The choices are: – Yes – No (default) – Only Solid Body Edges – Only Surface Body Edges • Edge/Edge: Sets the default preference1 (p. 76) for automatic contact detection between edges of different parts. The choices are Yes or No. The default is No. • Priority: Sets the default preference1 (p. 76) for the types of contact interaction priority between a given set of parts. The choices are: – Include All (default) – Face Overrides – Edge Overrides • Revolute Joints: Sets the default preference for automatic joint creation of revolute joints. The choices are Yes and No. The default is Yes. • Fixed Joints: Sets the default preference for automatic joint creation of fixed joints. The choices are Yes and No. The default is Yes. 1

Unless changed here in the Options dialog box, the preference remains persistent when starting any Workbench project.

The Transparency category includes the following exclusive controls for this category. There are no counterpart settings in the Details view.

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Customizing the Mechanical Application • Parts With Contact: Sets transparency of parts in selected contact region so the parts are highlighted. The default is 0.8. The range is from 0 to 1. • Parts Without Contact: Sets transparency of parts in non-selected contact regions so the parts are not highlighted. The default is 0.1. The range is from 0 to 1. The Default category allows you to change the default values in the Details view for the following: • Type: Sets the definition type of contact. The choices are: – Bonded (default) – No Separation – Frictionless – Rough – Frictional • Behavior: Sets the contact pair. The choices are: – Program Controlled (default) – Asymmetric – Symmetric – Auto Asymmetric • Formulation: Sets the type of contact formulation method. The choices are: – Program Controlled (default) – Augmented Lagrange – Pure Penalty – MPC – Normal Lagrange • Update Stiffness: Enables an automatic contact stiffness update by the program. The choices are: – Program Controlled (default) – Never – Each Iteration – Each Iteration, Aggressive • Shell Thickness Effect (p. 508): This settings allows you to automatically include the thickness of surface bodies during contact calculations. The default setting is No. • Auto Rename Connections: Automatically renames joint, spring, contact region, and joint condition objects when Type or Scoping are changed. The choices are Yes and No. The default is Yes. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Convergence The Convergence category allows you to change the default values in the Details view for the following: • Target Change: Change of result from one adapted solution to the next. The default is 20. The range is from 0 to 100. • Allowable Change: This should be set if the criteria is the max or min of the result. The default is Max. The Solution category allows you to change the default values in the Details view for the following: • Max Refinement Loops: Allows you to change the number of loops. The default is 1. The range is from 1 to 10.

Import The Import category allows you to specify preferences for when you import data into Mechanical. Currently, these preferences are for importing delamination interfaces from the ANSYS Composite PrepPost (ACP) application. • Create Delamination Objects: This option controls the automatic creation of Interface Delamination objects in Mechanical when importing layered section data from ACP. When Interface layers are specified in ACP, Interface Delamination objects corresponding to Interface Layers are automatically inserted into the Mechanical Tree Outline under the Fracture object. The default setting is Yes. • Delete Invalid Objects: This option controls the deletion of Invalid Interface Delamination objects scoped to Interface Layers from ACP. When an Interface Layer specified in ACP is deleted, the corresponding Interface Delamination object is deleted in Mechanical when the project is refreshed. The default settings is No. This default setting suppresses invalid objects instead of automatically deleting them.

Export The Export category provides the following exclusive settings. There are no counterpart settings in the Details view. • Automatically Open Excel: Excel will automatically open with exported data. The default is Yes. • Include Node Numbers: Node numbers will be included in exported file. The default is Yes. • Include Node Location: Node location can be included in exported file. The default is No.

Fatigue The General category allows you to change the default values in the Details view for the following: • Design Life: Number of cycles that indicate the design life for use in fatigue calculations. The default is 1e9. • Analysis Type: The default fatigue method for handling mean stress effects. The choices are: – SN - None (default) – SN - Goodman – SN - Soderberg 78

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Customizing the Mechanical Application – SN - Gerber – SN - Mean Stress Curves The Goodman, Soderberg, and Gerber options use static material properties along with S-N data to account for any mean stress while Mean-Stress Curves use experimental fatigue data to account for mean stress. The Cycle Counting category allows you to change the default values in the Details view for the following: • Bin Size: The bin size used for rainflow cycle counting. A value of 32 means to use a rainflow matrix of size 32 X 32. The default is 32. The range is from 10 to 200. The Sensitivity category allows you to change the default values in the Details view for the following: • Lower Variation: The default value for the percentage of the lower bound that the base loading will be varied for the sensitivity analysis. The default is 50. • Upper Variation: The default value for the percentage of the upper bound that the base loading will be varied for the sensitivity analysis. The default is 150. • Number of Fill Points: The default number of points plotted on the sensitivity curve. The default is 25. The range is from 10 to 100. • Sensitivity For: The default fatigue result type for which sensitivity is found. The choices are: – Life (default) – Damage – Factor of Safety

Frequency The Frequency category allows you to change the default values in the Details view for the following: • Max Number of Modes: The number of modes that a newly created frequency branch will contain. The default is 6. The range is from 1 to 200. • Limit Search to Range: You can specify if a frequency search range should be considered in computing frequencies. The default is No. • Min Range (Hz): Lower limit of search range. The default is 0. • Max Range (Hz): Upper limit of search range. The default is 100000000. • Cyclic Phase Number of Steps: The number of intervals to divide the cyclic phase range (0 - 360 degrees) for frequency couplet results in cyclic modal analyses.

Geometry The Geometry category allows you to change the default values in the Details view for the following: • Nonlinear Material Effects: Indicates if nonlinear material effects should be included (Yes), or ignored (No). The default is Yes. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Application Interface • Thermal Strain Calculation: Indicates if thermal strain calculations should be included (Yes), or ignored (No). The default is Yes.

Note This setting applies only to newly attached models, not to existing models. The Material category provides the setting Prompt for Model Refresh on Material Edit. This setting relates to the material Assignment property. If you choose to edit a material or create/import a new material via this property, the application displays a message (illustrated below) reminding you to refresh the Model cell in the Workbench Project Schematic. The default setting is Yes. The message in Mechanical provides you with the option to not show the message again. This option is in addition to this method of changing this setting to No.

Graphics The Default Graphics Options category allows you to change the default values in the Details view for the following: • Max Number of Annotations to Show: A slider that specifies the number of annotations that are shown in the legend and the graphics. The possible values range from 0 to 50. The default is 10. • Show Min Annotation: Indicates if Min annotation will be displayed by default (for new databases). The default is No. • Show Max Annotation: Indicates if Max annotation will be displayed by default (for new databases). The default is No. • Contour Option: Selects default contour option. The choices are: – Smooth Contour – Contour Bands (default) – Isolines – Solid Fill • Flat Contour Tolerance: Flat contours (no variation in color) display if the minimum and maximum results values are equal. The comparison of the minimum and maximum values is made using scientific notation with the number of significant digits to the right of the decimal point as specified with the flat contour tolerance setting (3 to 9). Increasing this tolerance allows you to display contours for an otherwise too narrow range of values. Decreasing this tolerance prevents insignificant range variations from being contoured. This setting has a default value of 3.

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Customizing the Mechanical Application • Edge Option: Selects default edge option. The choices are: – No Wireframe (default) – Show Undeformed Wireframe – Show Undeformed Model – Show Elements • Highlight Selection: Indicates default face selection. The choices are: – Single Side (default) – Both Sides • Number of Circular Cross Section Divisions: Indicates the number of divisions to be used for viewing line body cross sections for circular and circular tube cross sections. The range is adjustable from 6 to 360. The default is 16. • Mesh Visibility: Indicates if mesh is automatically displayed when the Mesh object is selected in the Tree Outline, or if it’s only displayed when you select the Show Mesh button. The default is Automatic.

Miscellaneous The Miscellaneous category allows you to change the default values in the Details view for the following: • Load Orientation Type: Specifies the orientation input method for certain loads. This input appears in the Define By option in the Details view of the load, under Definition. – Vector (default) – Component The Image category includes the following exclusive controls for this category. There are no counterpart settings in the Details view. • Image Transfer Type: Defines the type of image file created when you send an image to Microsoft Word or PowerPoint, or when you select Print Preview. The choices are: – PNG (default) – JPEG – BMP The Post Processing (MAPDL Only) category includes the following controls for results files written by the Mechanical APDL solver: • Result File Caching: By holding substantial portions of a file in memory, caching reduces the amount of I/O associated with result file reading. The cache can, however, reduce memory that would otherwise be used for other solutions. The choices are: – System Controlled (default): The operating system determines whether or not the result file is cached for reading.

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Application Interface – Off: There is no caching during the reading of the result file. – Programmed Controlled: The Mechanical application determines whether or not the result file is cached for reading. The Save Options category includes the following controls for this category. • Save Project Before Solution: Sets the Yes / No default for the Save Project Before Solution setting located in the Project Details panel. Although you can set the default here, the solver respects the latest Save Project Before Solution setting in the Details panel. The default for this option is No. Selecting Yes saves the entire project immediately before solving (after any required meshing). If the project had never been previously saved, you can now select a location to save a new file. • Save Project After Solution: Sets the Yes / No default for the Save Project After Solution setting in the Project Details panel. The default for this option is No Selecting Yes Saves the project immediately after solving but before postprocessing. If the project had never been previously saved, nothing will be saved.

Note The save options you specify on the Project Details panel override the options specified in the Options dialog box and will be used for the current project.

Report The Figure Dimensions (in Pixels) category includes the following controls that allow you to make changes to the resolution of the report for printing purposes. • Chart Width - Default value equals 600 pixels. • Chart Height - Default value equals 400 pixels. • Graphics Width - Default value equals 600 pixels. • Graphics Height - Default value equals 500 pixels. • Graphics Resolution - Resolution values include: – Optimal Onscreen Display (1:1) – Enhanced Print Quality (2:1) – High-Resolution Print Quality (4:1) The Customization category includes the following controls: • Maximum Number of Table Columns: (default = 6 columns) Changes the number of columns used when a table is created. • Merge Identical Table Cells: merges cells that contain identical values. The default value is Yes. • Omit Part and Joint Coordinate System Tables: chooses whether to include or exclude Coordinate System data within the report. This data can sometimes be cumbersome. The default value is Yes.

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Customizing the Mechanical Application • Include Figures: specifies whether to include Figure objects as pictures in the report. You may not want to include figures in the report when large solved models or models with a mesh that includes many nodes and elements are involved. In these cases, figure generation can be slow, which could significantly slow down report generation. The default value is Yes.

Note This option applies only to Figure objects as pictures. Graph pictures, Engineering Data graphs, and result graphs (such as phase response in a harmonic analysis) are not affected and will appear regardless of this option setting.

• Custom Report Generator Folder: reports can be run outside of the Workbench installation directory by copying the Workbench Report2006 folder to a new location. Specify the new folder location in this field. See the Customize Report Content section for more information.

Analysis Settings and Solution The Solver Controls category allows you to change the default values in the Details view for the following: • Solver Type: Specifies which ANSYS solver will be used. The choices are: – Program Controlled (default) – Direct – Iterative • Use Weak Springs: specifies whether weak springs are added to the model. The Programmed Controlled setting automatically allows weak springs to be added if an unconstrained model is detected, if unstable contact exists, or if compression only supports are active. The choices include: – Program Controlled (default) – On – Off The Output Controls category allows you to change the default values in the Details view for the following: • Stress (Default setting = Yes) • Strain (Default setting = Yes) • Nodal Forces (Default setting = No) • Contact Miscellaneous (Default setting = No) • General Miscellaneous (Default setting = No) • Calculate Reactions (Default setting = Yes) • Calculate Thermal Flux (Default setting = Yes) Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Application Interface Output Controls (Modal): this category allows you to change the default value in the Details for the Store Modal Results option. The default setting is Program Controlled. The Output Controls (Random Vibration) category allows you to change the default value in the Details view for the following: • Keep Modal Results: include or remove modal results from the result file of random vibration analysis. The default setting is No. • Calculate Velocity: Write Velocity results to the results file. The default setting is Yes. • Calculate Acceleration: Write Acceleration results to the results file. The default setting is Yes. The Restart Controls category allows you to change the default value in the Details view for the following: • Generate Restart Points: Program Controlled (default setting) automatically generates restart points. Additional options include Manual, that provides user-defined settings, and Off, which restricts the creation of new restart points. • Retain Files After Full Solve: when restart points are requested, the necessary restart files are always retained for an incomplete solve due to a convergence failure or user request. However, when the solve completes successfully, you have the option to request to either keep the restart points by setting this field to Yes, or to delete them by setting this field to No. You can control these settings in the Details view of the Analysis Settings object under Restart Controls (p. 644), or here under Tools> Options in the Analysis Settings and Solution preferences list. The setting in the Details view overrides the preference setting. The Solution Information category allows you to change the default value in the Details view for the following: • Refresh Time: specifies how often any of the result tracking items under a Solution Information object get updated while a solution is in progress. The default is 2.5 s. • Activate FE Connection Visibility: specifies the value of the Activate Visibility property. The default setting is Yes. The Solution Settings category allows you to set the default value in the Details view for the following: • Results Availability: specifies what results to allow under the Solution object in Design Assessment systems when the Solution Selection object allows combinations. The default is Filter Combination Results. The Analysis Data Management category allows you to set the default value in the Details view for the Save MAPDL db control. Values are No (default) or Yes. The setting of the Future Analysis control (see Analysis Data Management Help section) can sometimes require the db file to be written. In this case, the Save MAPDL db control is automatically set to Yes.

Visibility This selection and category provides the Part Mesh Statistics setting. This setting allows you to display or hide the Statistics category in the Details view for Body and Part objects.

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Customizing the Mechanical Application

Wizard The Wizard Options category includes the following exclusive controls for this category. There are no counterpart settings in the Details view. • Default Wizard: This is the URL to the XML wizard definition to use by default when a specific wizard isn't manually chosen or automatically specified by a simulation template. The default is StressWizard.xml. • Flash Callouts: Specifies if callouts will flash when they appear during wizard operation. The default is Yes. The Skin category includes the following exclusive controls for this category. There are no counterpart settings in the Details view. • Cascading Style Sheet: This is the URL to the skin (CSS file) used to control the appearance of the Mechanical Wizard. The default is Skins/System.css. The Customization Options category includes the following exclusive controls for this category. There are no counterpart settings in the Details view. • Mechanical Wizard URL: For advanced customization. See Appendix: Workbench Mechanical Wizard Advanced Programming Topics for details. • Enable WDK Tools: Advanced. Enables the Wizard Development Kit. The WDK adds several groups of tools to the Mechanical Wizard. The WDK is intended only for persons interested in creating or modifying wizard definitions. The default is No. See the Appendix: Workbench Mechanical Wizard Advanced Programming Topics for details.

Note • URLs in the Mechanical Wizard follow the same rules as URLs in web pages. • Relative URLs are relative to the location of the Mechanical Wizard URL. • Absolute URLs may access a local file, a UNC path, or use HTTP or FTP.

User Preferences File The Mechanical application stores the configuration information from the Options dialog box in a file called a User Preference File on a per user basis. This file is created the first time you start the Mechanical application. Its default location is: %APPDATA%\Ansys\v145\%AWP_LOCALE145%\dsPreferences.xml

Setting Variables Variables provide you the capability to override default settings. To set variables: 1.

Choose Variable Manager from the Tools menu.

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Application Interface 2.

Right-click in the row to add a new variable.

3.

Enter a variable name and type in a value.

4.

Click OK. Variable name

Allowable Values

Description

DSMESH OUTPUT

filename

Writes mesher messages to a file during solve (default = no file written). If the value is a filename, the file is written to the temporary working folder (usually c:\temp). To write the file to a specific location, specify the full path.

DSMESH DEFEATUREPERCENT

a number between 1e-6 and 1e-3

Tolerance used in simplifying geometry (default = .0005).

Keep Modal Results

1

Set to 1 to include Modal analysis results in the result file for a Random Vibration Analysis.

Status The status box indicates if a particular variable is active or not. Checked indicates that the variable is active. Unchecked indicates that the variable is available but not active. This saves you from typing in the variable and removing it.

Using Macros The Mechanical application allows you to execute custom functionality that is not included in a standard Mechanical application menu entry via its Run Macro feature. The functionality is defined in a macro a script that accesses the Mechanical application programming interface (API). Macros can be written in Microsoft's JScript or VBScript programming languages. Several macro files are provided with the ANSYS Workbench installation under \ANSYS Inc\v150\AISOL\DesignSpace\DSPages\macros. Macros cannot currently be recorded from the Mechanical application. To access a macro from the Mechanical application: 1.

Choose Run Macro... from the Tools menu.

2.

Navigate to the directory containing the macro.

3.

Open the macro. The functionality will then be accessible from the Mechanical application.

Working with Graphics Here are some tips for working with graphics: • You can use the ruler, shown at the bottom of the Geometry window, to obtain a good estimate of the scale of the displayed geometry or results (similar to using a scale on a geographic map). The ruler is useful when setting mesh sizes. • You can rotate the view in a geometry selection mode by dragging your middle mouse button. You can zoom in or out by rolling the mouse wheel.

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Working with Graphics • Hold the control key to add or remove items from a selection. You can paint select faces on a model by dragging the left mouse button. • You can pan the view by using the arrow keys. You can rotate the view by using the control key and arrow keys. • Click the interactive Controlling the Viewing Orientation (p. 113) to quickly change the graphics view. • Use the stack of rectangles in the lower left corner of the Geometry Window (p. 20) to select faces hidden by your current selection. • To rotate about a specific point in the model, switch to rotate mode and click the model to select a rotation point. Click off the model to restore the default rotation point. • To multi-select one or more faces, hold the Ctrl key and click the faces you wish to select, or use Box Select to select all faces within a box. The Ctrl key can be used in combination with Box Select to select faces within multiple boxes. • Click the Using Viewports (p. 106) icon to view up to four images in the Geometry Window (p. 20). • Controls are different for Graphs & Charts. More information is available in the following topics: Selecting Geometry Selecting Nodes Selecting Elements Defining Direction Using Viewports Controlling Graphs and Charts Managing Graphical View Settings Creating Section Planes Controlling the Viewing Orientation Viewing Annotations Controlling Lighting Inserting Comments, Images, and Figures

Selecting Geometry This section discusses cursor modes and how to select and pick geometry in the Geometry window. It includes information on the following: Pointer Modes (p. 88) Highlighting (p. 88) Picking (p. 88) Blips (p. 89) Painting (p. 89) Depth Picking (p. 89) Selection Filters (p. 90) Extend Selection Menu (p. 91) Selection Modes (p. 90) For Help on how to select mesh nodes and elements, see the Selecting Nodes and Selecting Elements sections. Many of the same selection and picking tools are employed for mesh selections.

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Pointer Modes The pointer in the graphics window is always either in a picking filter mode or a view control mode. When in a view control mode the selection set is locked. To resume the selection, repress a picking filter button. The Graphics Toolbar offers several geometry filters and view controls as the default state, for example, face, edge, rotate, and zoom. If a Geometry field in the Details View (p. 11) has focus, inappropriate picking filters are automatically disabled. For example, a pressure load can only be scoped to faces. If the Direction field in the Details View (p. 11) has focus, the only enabled picking filter is Select Direction. Select Direction mode is enabled for use when the Direction field has focus; you never choose Select Direction manually. You may manipulate the view while selecting a direction. In this case the Select Direction button allows you to resume your selection.

Highlighting Hovering your cursor over a geometry entity highlights the selection and provides visual feedback about the current pointer behavior (e.g. select faces) and location of the pointer (e.g. over a particular face). As illustrated here, the face edges are highlighted in colored dots.

Picking A pick means a click on visible geometry. A pick becomes the current selection, replacing previous selections. A pick in empty space clears the current selection. By holding the Ctrl key down, you can add additional selections or remove existing selections. Clicking in empty space with Ctrl depressed does not clear current selections. For information on picking nodes, see Selecting Nodes (p. 96).

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Working with Graphics

Blips As illustrated below, when you make a selection on a model, a crosshair “blip” appears.

The blip serves to: • Mark a picked point on visible geometry. • Represent a ray normal to the screen passing through all hidden geometry. When you make multiple selections using the Ctrl key, the blip is placed at the last selection entity. Clicking in empty space clears your current selection, but the blip remains in its last location. Once you have cleared a selection, hold the Ctrl key down and click in clear space again to remove the blip.

Note This is important for depth picking, a feature discussed below.

Painting Painting means dragging the mouse on visible geometry to select more than one entity. A pick is a trivial case of painting. Without holding the Ctrl key down, painting picks all appropriate geometry touched by the pointer.

Depth Picking Depth Picking allows you to pick geometry through the Z-order behind the blip. Whenever a blip appears above a selection, the graphics window displays a stack of rectangles in the lower left corner. The rectangles are stacked in appearance, with the topmost rectangle representing the visible (selected) geometry and subsequent rectangles representing geometry hit by a ray normal to the screen passing through the blip, front to back. The stack of rectangles is an alternative graphical

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Application Interface display for the selectable geometry. Each rectangle is drawn using the same edge and face colors as its associated geometry. Highlighting and picking behaviors are identical and synchronized for geometry and its associated rectangle. Moving the pointer over a rectangle highlights both the rectangle its geometry, and vice versa. Ctrl key and painting behaviors are also identical for the stack. Holding the Ctrl key while clicking rectangles picks or unpicks associated geometry. Dragging the mouse (Painting (p. 89)) along the rectangles picks geometry front-to-back or back-to-front.

Selection Filters The mouse pointer in the graphics window is either in a picking filter mode or a view control mode. A depressed button in the graphics toolbar indicates the current mode. Filter

Behavior

Vertices

Vertices are represented by concentric circles about the same size as a blip. The circumference of a circle highlights when the pointer is within the circle.

Edges

Painting may be used to pick multiple edges or to "paint up to" an edge (to avoid tediously positioning the pointer prior to clicking).

Faces

Allows selection of faces. Highlighting occurs by dotting the banding edges of the face.

Bodies

Picking and painting: select entire bodies. Highlighted by drawing a bounding box around the body. The stack shows bodies hidden behind the blip (useful for selecting contained bodies).

Selection Modes The Select Mode toolbar button allows you to select items designated by the Selection Filters through the Single Select or Box Select drop-down menu options. • Single Select (default): Click on an item to select it. • Box Select: Define a box that selects filtered items. When defining the box, the direction that you drag the mouse from the starting point determines what items are selected, as shown in the following figures:

– Dragging to the right to form the box selects entities that are completely enclosed by the box. – Visual cue: 4 tick marks completely inside the box.

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– Dragging to the left to form the box selects all entities that touch the box. – Visual cue: 4 tick marks that cross the sides of the box. • Box Volume Select: Available for node-based Named Selections only. Selects all the surface and internal node within the box boundary across the cross-section. The line of selection is normal to the screen. • Lasso Select: Available for node-based Named Selections only. Selects surface nodes that occur within the shape you define. • Lasso Volume Select: Available for node-based Named Selections only. Selects nodes that occur within the shape you define.

Note Selection shortcuts: • You can use the Ctrl key for multiple selections in both modes. • You can change your selection mode from Single Select to Box Select by holding the right mouse button and then clicking the left mouse button. • Given a generated mesh and that the Mesh Select option is active, holding the right mouse button and then clicking the left mouse button scrolls through the available selection options (single section, box selection, box volume, lasso, lasso volume).

Extend Selection Menu The Extend Selection drop-down menu is enabled only for edge or face selection mode and only with a selection of one or more edges or faces. The following options are available in the drop-down menu: • Extend to Adjacent – For faces, Extend to Adjacent searches for faces adjacent to faces in the current selection that meet an angular tolerance along their shared edge.

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Single face selected in part on the left.

Additional adjacent faces selected after Extend to Adjacent option is chosen.

– For edges, Extend to Adjacent searches for edges adjacent to edges in the current selection that meet an angular tolerance at their shared vertex.

Single edge selected in part on the left.

Additional adjacent edges selected after Extend to Adjacent option is chosen.

• Extend to Limits – For faces, Extend to Limits searches for faces that are tangent to the current selection as well as all faces that are tangent to each of the additional selections within the part. The selections must meet an angular tolerance along their shared edges.

Single face selected in part on the left.

Additional tangent faces selected after Extend to Limits option is chosen.

– For edges, Extend to Limits searches for edges that are tangent to the current selection as well as all edges that are tangent to each of the additional selections within the part. The selections must meet an angular tolerance along their shared vertices.

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Single edge selected in part on the left.

Additional tangent edges selected after Extend to Limits option is chosen.

• Extend to Instances (available only if CAD pattern instances are defined in the model): When a CAD feature is repeated in a pattern, it produces a family of related topologies (for example, vertices, edges, faces, bodies) each of which is named an "instance". Using Extend to Instances, you can use one of the instances to select all others in the model. As an example, consider three parts that are instances of the same feature in the CAD system. First select one of the parts.

Then, choose Extend to Instances. The remaining two part instances are selected.

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See CAD Instance Meshing for further information. • Extend to Connection – As described in Define Connections (p. 132), connections can be contact regions, joints, mesh connections, and so on. Available for faces only, the Extend to Connection option is especially useful for assembly meshing as an aid in picking faces related to flow volumes. For example, if you are using a Fluid Surface object to help define a virtual body, you can generate connections, pick one face on each body of the flow volume, and then select Extend to Connection. As a result, the faces related to the flow volume are picked to populate the Fluid Surface object. Extend to Connection searches for faces that are adjacent to the current selection as well as all faces that are adjacent to each of the additional selections within the part, up to and including all connections on the selected part. This does not include all faces that are part of a connection—it includes only those faces that are part of a connection and are also on the selected part. If an edge used by a connection is encountered, the search stops at the edge; a face across the edge is not selected. If there are no connections, all adjacent faces are selected. If the current selection itself is part of a connection, it remains selected but the search stops.

Note → Virtual Body and Fluid Surface objects are fluids concepts, and as such they are not supported by Mechanical solvers. → The extent of the faces that will be included depends greatly on the current set of connections, as defined by the specified connections criteria (for example, Connection Type, Tolerance Value, and so on). By modifying the criteria and regenerating the connections, a different set of faces may be included. Refer to Common Connections Folder Operations for Auto Generated Connections (p. 501) for more information. → The figures below illustrate simple usage of the Extend to Connection option. Refer to Defining Virtual Bodies in the Meshing help for a practical example of how you can use

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Working with Graphics the Extend to Connection option and virtual bodies together to solve assembly meshing problems.

Single face selected in part.

Single face selected in part. In this example, a multiple edge to single face connection is defined.

Additional connected faces selected after Extend to Connection option is chosen.

Additional connected faces selected after Extend to Connection option is chosen. When the connection is encountered, search stops at edge.

For all options, you can modify the angle used to calculate the selection extensions in the Workbench Options dialog box setting Extend Selection Angle Limit under Graphics Interaction.

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Selecting Nodes As with geometry selection, you use many of the same selection and picking tools for mesh node selections. Once you have generated the mesh on your model, you use picking tools to select individual or multiple nodes on a mesh. You use node selections to define objects such as a node-based coordinate system or node-based Named Selections as well as examining solution information about your node selections. This section describes the steps to perform node selections on a mesh. Additional topics included in this section, as show below, cover additional uses for the node selection capability. Node Selection (p. 96) Selection Modes for Node Selection (p. 97) View Node Information (p. 98) Select Mesh Nodes on a Result Contour (p. 99) Also see the following sections for the steps to create node-based coordinate systems and Named Selections. Creating a Coordinate System by Direct Node Selection Specifying Named Selections by Direct Node Selection

Node Selection To select individual nodes: 1.

Generate a mesh by highlighting the Mesh object and clicking the Generate Mesh button.

2.

From the Select Type list, choose Select Mesh.

3.

Choose the appropriate selection tool in the Select Mode list. For more information on the node-based selection modes, see Selection Modes for Node Selection (p. 97).

Note • The Vertex geometry selection option is the only selection option available to pick nodes. • When working with Line Bodies: Nodes can be selected using volume selection modes only (Box Volume Select or Lasso Volume Select). • When working with Line Bodies and Surface Bodies: it is recommended that you turn off the Thick Shells and Beams option (View>Thick Shells and Beams). This option changes the graphical display of the model’s thickness and as a result can affect how your node selections are displayed.

4.

Select individual nodes or define the shape to select nodes. You can now define a coordinate system or named selection from selected nodes.

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Selection Modes for Node Selection Selects individual nodes or a group of nodes on the surface. Single Select Selects all the surface nodes within the box boundary for all the surfaces oriented toward the screen.

Box Select

Selects all the surface and internal nodes within the box boundary across the crosssection. The line of selection is normal to the screen.

Box Volume Select

Is similar to the Box Select mode. Selects surface nodes that occur within the shape you define for surfaces oriented toward the screen.

Lasso Select

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Application Interface Similar to Box Volume Select mode. Selects the nodes that occur within the shape you define.

Lasso Volume Select

Tip • To select multiple nodes, press the Ctrl key or press the left mouse and then drag over the surface. You can also create multiple node groups at different locations using the Ctrl key. • To select all internal and surface nodes, use the Box Volume Select or Lasso Select tool and cover the entire geometry within the selection tool boundary.

View Node Information You can view information such as the location of each selected node and a summary of the group of nodes in the Selection Information window. A brief description of the selected nodes is also available on the Status Bar of the application window. To view node id and location information: 1. Select the nodes you want to include in a Named Selection. 2. Click View>Windows >Selection Information The following options are available as drop-down menu items in the Selection Information window. Selection Information Field

Description

Coordinate System

Updates the X, Y, and Z information based on the selected coordinate system.

Show Individual and Summary

Shows both the node Summary and information on each node.

Show Individual

Shows information related to each node.

Show Summary

Shows only a summary of selected nodes.

For more information see the Selection Information Toolbar section.

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Select Mesh Nodes on a Result Contour Nodes (from the original mesh) can be selected even if they don’t have values for the selected result, as in a path or surface scoped result.

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Application Interface The positions of selected nodes reported in the Selection Information window are those from nondeformed mesh.

Note If the graphics expansion is used (for shells and cyclic expansion, for example), the selection will work on the expanded graphics, while the reported node ID and position will be those in the non-expanded mesh. To eliminate confusion, switch the expansion off.

Creating a Coordinate System by Direct Node Selection You can select one or more nodes and then create a coordinate system directly in the Graphics window. The new coordinate system is created at the location of the selected node or the centroid of multiple nodes using the (X, Y, Z) locations, rather than the nodes themselves, to ensure that the location does not change upon re-meshing. To create a coordinate system from nodes in the Graphics window: 1.

Select one or more nodes as discussed in Selecting Nodes (p. 96).

2.

Right-click and select Create Coordinate System. A new coordinate system is created at the location of the selected node or the centroid of multiple nodes.

Note The mesh is not shown after coordinate system creation. To view the mesh again, from the Tree Outline, select Mesh.

If you re-mesh the body at this point, you will see that the coordinate system remains in the same location, as it is based on node location rather than node number.

Creating an Aligned Coordinate System You can also select an individual node and create an aligned coordinate system on a solved vector principal stress or strain result.

Note While you cannot create an aligned coordinate system based on multiple nodes, you can create a local coordinate system at the centroid with an axis oriented in the direction of the global coordinate system. To create an aligned coordinate system: 1.

From the Tree Outline, select a Vector Principal Stress or Vector Principal Strain result.

2.

Select a single node using the method outlined in Selecting Nodes (p. 96).

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Right-click in the Graphics window and select Create Aligned Coordinate System. A coordinate system is created. The Y-axis of the local coordinate system is oriented in the direction of S1 (direction of max. principal stress).

Note Vector Principal Stress and Vector Principal Strain results cannot be applied to line bodies or a node located on a line body. As a result, any automatically generated (aligned) coordinate system would be incorrect.

Specifying Named Selections by Direct Node Selection You create node-based Named Selections in the graphical viewer by scoping selections to single nodes, a group of surface nodes, or a group of nodes across a geometry cross-section.

Note You can make direct node selections when working with beams (line bodies) using the Worksheet. Direct graphical selection is also available but requires the appropriate selection tool (Select Mode) as described in the Node Selection section. To define node-based Named Selections: 1. Select individual nodes or define the shape to select nodes, as described in Selecting Nodes (p. 96).

Note For accuracy, ensure that the selected node lies within the scoped area of the result

2. In the Graphics window, right-click and select Create Named Selection. 3. Enter a name for the Named Selection and click OK.

Note • If you select a large number of nodes (order of magnitude: 10,000), you are prompted with a warning message regarding selection information time requirements. • Following a remesh or renumber, all nodes are removed from named selections. If named selections were defined with Scoping Method set to Worksheet and if the Generate on Remesh field was set to Yes in the Details view of the Named Selection folder, then the nodes are updated. Otherwise, node scoping does not occur and the named selection will be empty.

Selecting Elements Once you have generated the mesh on your model, you can select individual elements or multiple elements on a mesh using the appropriate selection filters (Body) and modes (Single Select and Box Select). The following topics describe element-based selection methods and features: Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Application Interface • Selecting Elements (p. 102) • Viewing Element Information (p. 103) • Specifying Element-Based Named Selections (p. 104)

Selecting Elements To select an element or elements: 1.

Generate the mesh by highlighting the Mesh object and clicking the Generate Mesh button.

2.

From the Select Type drop-down menu on the Graphics Toolbar, choose Select Mesh.

3.

Choose the desired selection tool from the Select Mode drop-down menu on the Graphics Toolbar. Active options include either Single Select or Box Selection.

4.

Select an individual element or multiple elements. To select multiple elements: • Hold the Ctrl key and click the desired elements individually. You can also deselect elements by holding down the Ctrl key clicking an already selected element. • Hold the left mouse button and drag the cursor across multiple elements. • Use the Box Select tool to select all elements within a box. The Ctrl key can also be used in combination with Box Select to select multiple boxes of elements.

Note • The Body Selection Filter must be used to pick elements. • As illustrated below for the example Named Selection, Graphically Selected Elements, when the Show Mesh feature is active, the elements of a named selection, or multiple named selections, are highlighted. Otherwise, the elements are drawn.

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Working with Graphics Show Mesh On

Show Mesh Off

• When working with Line Bodies and Surface Bodies: it is recommended that you turn off the Thick Shells and Beams option (View>Thick Shells and Beams). This option changes the graphical display of the model’s thickness and as a result can affect how your element selections are displayed. • The Select All (Ctrl+A) option is not available when selecting elements.

Viewing Element Information As illustrated below, you can view information about your element selections, such as Element Type, Element ID, as well as the body that the element is associated with using the Selection Information window. Once you have selected your desired element or elements, display the Selection Information window by selecting View>Windows >Selection Information.

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Note The Status Bar at the bottom of the application window also displays the number of elements you currently have selected. For additional information, see the Selection Information Toolbar section.

Specifying Element-Based Named Selections To create an element-based Named Selection: 1.

Select individual or multiple elements as described above.

2.

With your desired element selections highlighted, right-click the mouse and select Create Named Selection from the context menu.

3.

Enter a name for the Named Selection and click OK.

Element-based Named Selections are written into the MAPDL input file and this data can be used by the Command object for further processing.

Defining Direction Orientation may be defined by any of the following geometric selections: • A planar face (normal to). • A straight edge. • Cylindrical or revolved face (axis of ). • Two vertices. This section discusses the following topics: Direction Defaults (p. 105) Highlighting Geometry in Select Direction Mode (p. 105) Selecting Direction by Face (p. 105)

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Direction Defaults If you insert a load on selected geometry that includes both a magnitude and a direction, the Direction field in the Details view states a particular default direction. For example, a force applied to a planar face by default acts normal to the face. One of the two directions is chosen automatically. The load annotation displays the default direction.

Highlighting Geometry in Select Direction Mode Unlike other picking filters (where one specific type of geometry highlights during selection) the Select Direction filter highlights any of the following during selection: • Planar faces • Straight edges • Cylindrical or revolved faces • Vertices If one vertex is selected, you must hold down the Ctrl key to select the other. When you press the Ctrl key, only vertices highlight.

Selecting Direction by Face The following figure shows the graphic display after choosing a face to define a direction. The same display appears if you edit the Direction field later. • The selection blip indicates the hit point on the face. • Two arrows show the possible orientations. They appear in the lower left corner of the Geometry Window (p. 20) window.

If either arrow is clicked, the direction flips. When you finish editing the direction, the hit point (initially marked by the selection blip) becomes the default location for the annotation. If the object has a location as well as a direction (e.g. Remote Force), the location of the annotation will be the one that you specify, not the hit point.

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Note The scope is indicated by painting the geometry.

Using Viewports The Viewports toolbar button allows you to split the graphics display into a maximum of four simultaneous views. You can see multiple viewports in the Geometry Window (p. 20) window when any object in the tree is in focus except Project. You can choose one, horizontal, vertical, or four viewports. Each viewport can have separate camera angles, labels, titles, backgrounds, etc. Any action performed when viewports are selected will occur only to the active viewport. For example, if you animate a viewport, only the active viewport will be animated, and not the others.

A figure can be viewed in a single viewport only. If multiple viewports are created with the figure in focus, all other viewports display the parent of the figure.

Note Each viewport has a separate Section tool, and therefore separate Section Plane. The concept of copying a Section Plane from one window to the next does not exist. If you want Section Planes in a new window, you must create them in that window. Viewports are not supported in stepped analyses.

Controlling Graphs and Charts The following controls are available for Graphs/Charts for Adaptive Convergence (p. 1065), and Fatigue Results (p. 961) result items. Feature

Control

Pan

Right Mouse Button

Zoom

Middle Mouse Button

Box Zoom

Alt+Left Mouse Button

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Working with Graphics Rotate (3D only)

Left Mouse Button

Perspective Angle (3D only)

Shift+Left Mouse Button

Display Coordinates (2D only)

Ctrl+Left Mouse Button along graph line

Tips for working with graphs and charts: • Some features are not available for certain graphs. • Zoom will zoom to or away from the center of the graph. Pan so that your intended point of focus is in the center prior to zooming. • If the graph has a Pan/Zoom control box, this can be used to zoom (shrink box) or pan (drag box). • Double-clicking the Pan/Zoom control box will return it to its maximum size.

Managing Graphical View Settings Graphical view settings help to ensure a consistent graphical view. With the manage view functionality, you can save graphical views and return to a specific view at any time. To maintain a consistent model view list between multiple projects, you can export the graphical view list, and then import it into a different project. To view the Manage Views window, do one of the following: • In the toolbar, click the Manage Views

button.

• Select View>Windows>Manage Views. The Manage Views window opens. This section discusses the following topics: Creating a View Applying a View Renaming a View Deleting a View Replacing a Saved View Exporting a Saved View List Importing a Saved View List Copying a View to Mechanical APDL

Creating a View To save the current graphical view: 1.

In the Manage Views window, click the Create a View button. A new entry with the naming convention of “View #” is created in the Manage Views window. This entry is selected for renaming.

2.

If desired, enter a new name for the graphical view.

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Application Interface You can now return to this view at any time using this view entry.

Note You must save the project to save your created views in the Manage Views window.

Applying a View Saved graphical views are listed in the Manage Views window. You can return to a saved view at any time. To return to a saved graphical view: 1.

In the Manage Views window, select the view.

2.

Click the Apply View button.

The Geometry window reflects the saved graphical view.

Renaming a View To rename a saved graphical view: 1.

In the Manage Views window, select the view you want to rename.

2.

Click the Rename button, or press F2.

3.

Enter the new view name.

4.

Click the Apply button.

Deleting a View To delete a saved graphical view: 1.

In the Manage Views window, select the view you want to delete.

2.

Click the Delete button.

Replacing a Saved View To replace a saved view with the current graphical view: 1.

In the Manage Views window, select the view you want to update.

2.

Click the Replace saved view based on current graphics button.

Exporting a Saved View List You can export a saved graphical view list to an XML file. This file can then be imported into other projects. To export a saved view list:

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In the Manage Views window, click the Export button. The Save As window appears.

2.

Navigate to the file directory where you want to store the XML file and enter the desired file name.

3.

Click Save.

Importing a Saved View List Saved view lists can be exported to XML files. You can then import a saved view list from an XML file to a different project. To import a saved graphical view list: 1.

In the Manage Views window, click the Import button. The Open window appears.

2.

Select the file you want to import.

3.

Click Open.

Copying a View to Mechanical APDL You can copy a saved graphical view as a Mechanical APDL command and insert the command into a Mechanical APDL file. The view in Mechanical APDL will then be consistent with the selected graphical view. To copy a graphical view to Mechanical APDL: 1.

In the Manage Views window, right-click a view and select Copy as MAPDL Command.

2.

Create or open an existing Commands (APDL) file.

3.

Paste the new Mechanical APDL command into the file. The settings structure is: /FOC /VIEW /ANG /DIST

4.

Select the Solve button, and the new view is available in the Commands (APDL) file.

Creating Section Planes The Section Plane feature creates cuts or slices on your model so that you can view internal geometry, mesh, and/or result displays. You can create as many as six Section Planes for a model. Once this maximum is met, the feature becomes disabled until less than six planes exist. Selecting the New Section Plane button ( ) in the Graphics toolbar initiates the function and displays the Section Planes window illustrated below.

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The Section Planes window provides the following capabilities. Icon Button

Application-Level Command New Section Plane Edit Section Plane Delete Section Plane Show Whole Elements (available when the Mesh object is selected)

Example 1: Section Plane Example As an example, consider the model shown below that is subjected to a horizontal and a vertical slice.

The mesh display will show 75% of the model while the geometry display will show 25% of the model.

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For additional information about the use of the Section Plane feature, see the following topics. Adding a Section Plane Using Section Planes Modifying a Section Plane Deleting a Section Plane

Adding a Section Plane To add a section plane: 1.

In the Section Planes window, click the New Section Plane button.

2.

Drag the mouse pointer across the geometry where you want to create a section plane.

The new section plane is listed in the Section Planes window with a default name of “Section Plane #.” The checkmark next to the plane’s name indicates it is an active section plane. 3.

You can construct additional Section Planes by clicking the New Section Plane button and dragging additional lines across the model. Note that activating multiple planes displays multiple sections:

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Using Section Planes • Maneuver between multiple planes by highlighting the plane names In the Section Planes window. • When you are on a Mesh display you can use the Show Whole Elements button to display the adjacent elements to the section plane which may be desirable in some cases. • For result displays, if the Section Plane feature is active, choosing Show Undeformed WireFrame from the Edges Options drop down menu on the Result Context Toolbar (p. 59) actually displays the wireframe with the deformations added to the nodes. This is intended to help you interpret the image when you drag the anchor across smaller portions of the model. • Unchecking all the planes effectively turns the Section Plane feature off.

Note that in incidences such as very large models where the accessible memory is exhausted, the New Section Plane tool will revert to a Hardware Slice Mode that prohibits visualization of the mesh on the cut-plane. The Section Plane acts differently depending if you are viewing a result, mesh, or geometry display. When viewing a result or a mesh, the cut is performed by a software algorithm. When viewing geometry, the cut is performed using a hardware clipping method. This hardware clipping cuts away the model in a subtractive method. The software algorithm cuts away the model but always starts with the whole model.

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Working with Graphics Geometry Display Example

Mesh Display Example

Note that the software algorithm caps the surfaces created by the section plane as opposed to the hardware clipping method. When capping, the software algorithm creates a visible surface at the intersection of the object and the section plane."

Modifying a Section Plane To modify a section or capping plane: 1.

In the Section Planes window, select the plane you want to edit.

2.

Click the Edit Section Plane button. The section plane’s anchor appears.

3.

Drag the Section Plane or Capping Plane anchor to change the position of the plane.

You can click on the line on either side of the anchor to view the exterior on that side of the plane. The anchor displays a solid line on the side where the exterior is being displayed. Clicking on the same side a second time toggles between solid line and dotted line, i.e. exterior display back to section display. Note that for Geometry display, a capped view is always shown.

Deleting a Section Plane To delete a section or capping plane: 1.

In the Section Planes window, select the plane you want to delete.

2.

Click the Delete Section Plane button.

Controlling the Viewing Orientation The triad and rotation cursors allow you to control the viewing orientation as described below. Triad

• Located in lower right corner. • Visualizes the world coordinate system directions.

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Application Interface • Positive directions arrows are labeled and color-coded. Negative direction arrows display only when you hover the mouse cursor over the particular region. • Clicking an arrow animates the view such that the arrow points out of the screen. • Arrows and the isometric sphere highlight when you point at them. • Isometric sphere visualizes the location of the isometric view relative to the current view. • Clicking the sphere animates the view to isometric. Rotation Cursors

Click the Rotate button

to display and activate the following rotation cursors:

•

Free rotation.

•

Rotation around an axis that points out of the screen (roll).

•

Rotation around a vertical axis relative to the screen ("yaw" axis).

•

Rotation around a horizontal axis relative to the screen ("pitch" axis).

Cursor Location Determines Rotation Behavior The type of rotation depends on the starting location of the cursor. In general, if the cursor is near the center of the graphics window, the familiar 3D free rotation occurs. If the cursor is near a corner or edge, a constrained rotation occurs: pitch, yaw or roll. Specifically, the circular free rotation area fits the window. Narrow strips along the edges support pitch and yaw. Corner areas support roll. The following figure illustrates these regions.

Viewing Annotations Annotations provide the following visual information: • Boundary of the scope region by coloring the geometry for edges, faces or vertices. 114

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Working with Graphics • An explicit vertex within the scope. • A 3D arrow to indicate direction, if applicable. • Text description or a value. • A color cue (structural vs. thermal, etc.).

Note The custom annotations you add using Label remain visible even when you suppress the body. This section addresses the following types of annotations: Highlight and Selection Graphics (p. 115) Scope Graphics (p. 115) Annotation Graphics and Positioning (p. 116) Annotations of Multiple Objects (p. 117) Rescaling Annotations (p. 117) Solution Annotations (p. 118) In addition, you can also specify preferences for your annotations. For more information, see Specifying Annotation Preferences (p. 119).

Highlight and Selection Graphics You can interactively highlight a face. The geometry highlights when you point to it.

See Selecting Geometry (p. 87) for details on highlighting and selection.

Scope Graphics In general, selecting an object in the Tree Outline (p. 3) displays its Scope by painting the geometry and displays text annotations and symbols as appropriate. The display of scope via annotation is carried over into the Report Preview (p. 22) if you generate a figure. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Application Interface Contours are painted for results on the scoped geometry. No boundary is drawn.

Annotation Graphics and Positioning A label consists of a block arrow cross-referenced to a color-coded legend. For vector annotations, a 3D arrow originates from the tip of the label to visualize direction relative to the geometry.

Use the pointer after selecting the Label toolbar button the annotation to a different location within the scope.

for managing annotations and to drag

• If other geometry hides the 3D point (e.g. the point lies on a back face) the block arrow is unfilled (transparent).

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Working with Graphics • The initial placement of an annotation is at the pick point. You can then move it by using the Label toolbar button for managing annotations. • Drag the label to adjust the placement of an annotation. During the drag operation the annotation moves only if the tip lies within the scope. If the pointer moves outside the scope, the annotation stops at the boundary.

Annotations of Multiple Objects When multiple individual objects or a folder (such as environment, contact, or named selections) are selected in the Tree Outline (p. 3), an annotation for each one appears on the geometry. The default number of annotations shown is 10, but you can change it to any value from 0 to 50 in the Graphics options. For more information, see Graphics (p. 80). Note that, if you have a large number of objects, you may want to display each object as a different color. For more information, see the Random Colors toolbar button documentation.

Rescaling Annotations This feature modifies the size of annotation symbols, such as load direction arrows, displayed in the Mechanical application. For example, and as illustrated below, you can reduce the size of the pressure direction arrow when zooming in on a geometry selection. To change the size of an annotation, click the Rescale Annotation toolbar button (

).

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Application Interface

Solution Annotations Solution annotations work similar to Annotations of Multiple Objects (p. 117). The Max annotation has red background. The Min annotation has blue background. Probe annotations have cyan backgrounds.

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Working with Graphics

• By default, annotations for Max and Min appear automatically for results but may be controlled by buttons in the Result Context Toolbar (p. 59). in the Result Context Toolbar (p. 59). Probe an• You may create "probe" annotations by clicking notations show the value of the result at the location beneath the tip, when initially constructed. When probe annotations are created, they do not trigger the database to be marked as save being needed (i.e. you will not be prompted to save). Be sure to issue a save if you wish to retain these newly created probe annotations in the database. Changes to the unit system deletes active probe annotations. In addition, probe annotations are not displayed if a Mechanical application database is opened in a unit system other than the one in which it was saved; however, the probe annotations are still available and display when the Mechanical application database is opened in the original unit system. • If you apply a probe annotation to a very small thickness, such as when you scope results to an edge, the probe display may seem erratic or non-operational. This is because, for ease of viewing, the colored edge result display is artificially rendered to appear larger than the actual thickness. You can still add a probe annotation in this situation by zooming in on the thin region before applying the probe annotation. • To delete a probe annotation, activate the Label button key.

, select the probe, and then press the Delete

• Probes will be cleared if the results are re-solved. • After adding one or more probe annotations, if you increase the number of viewports, the probe annotations only appear in one of the viewports. If you then decrease the number of viewports, you must first highlight the header in the viewport containing the probe annotations in order to preserve the annotations in the resulting viewports. • See the Solution Context Toolbar (p. 59) for more information.

Specifying Annotation Preferences The Annotation Preferences dialog box controls the visibility of all annotations, including custom annotations and annotation labels, annotations on objects such as cracks, point masses, and springs, and the coordinate system display. To set your annotation preferences: 1.

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Application Interface The Annotation Preferences dialog box appears. By default, all annotations are selected, and thus set to visible. 2.

Under Basic Annotations, select or clear the check boxes for the following options: • Annotations: Toggles the visibility of annotations in the graphics window. • User Defined Graphics Annotations: Toggles the visibility of custom user annotation in the graphics window. • Annotation Labels: Toggles the visibility of annotation labels in the graphics window.

3.

Under Remote Boundary Conditions, select or clear the check boxes for the following options: • Point Masses: Toggles the visibility of annotations for point masses. • Springs: Toggles the visibility of annotations for springs. • Beam Connections: Toggles the visibility of annotations for beam connections. • Bearings: Toggles the visibility of annotations for bearings.

Note The size range for Point Masses and Springs is from 0.2-2 (Small-0.2, Default-1, Large-2).

4.

Under Remote Boundary Conditions, slide the indicator to specify the size of the annotations for Point Masses and Springs.

5.

Under Additional Display Preferences, select or clear the check boxes for the following options: • Crack Annotations: Toggles the visibility of annotations on crack objects. • Individual Force Arrows on Surface Reactions: Toggles the visibility of individual force arrows on surface reactions. • Body Scoping Annotations: Toggles the visibility of annotations on body scoping.

6.

Under Mesh Display, select or clear the check boxes for the following options: • Mesh Annotations: Toggles the visibility of mesh node and mesh element annotations in Named Selection displays. • Node Numbers: Toggles the visibility of mesh node numbers in Named Selection, Mesh, and Result displays. • Plot Elements Attached to Named Selections: Toggles the visibility of elements for all items in the Named Selections group. For nodal Named Selections, this option shows the full elements, while for face or body Named Selections this option shows just the element faces. This option does not affect Line Bodies. You must have the Show Mesh button toggled off to see the elements in the Named Selection.

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Working with Graphics 7.

When you are finished specifying your annotation preferences, click Apply Changes to apply your preferences and leave the dialog box open, or click OK to apply and close.

Controlling Lighting The Details view properties of the Model object provide lighting controls that affect the display in the Graphics Window.

Inserting Comments, Images, and Figures You can insert Comment objects, Image objects, or Figure objects under various parent objects in the Mechanical tree to add text or graphical information that pertain specifically to those parent objects. Refer to their individual objects reference pages for descriptions. Additional information on Figure objects is presented below. Figures allow you to: • Preserve different ways of viewing an object (viewpoints and settings). • Define illustrations and captions for a report. • Capture result contours, mesh previews, environment annotations etc., for later display in Report. Clicking the Figure button in the Standard Toolbar (p. 49) creates a new Figure object inside the selected object in the Tree Outline (p. 3). Any object that displays 3D graphics may contain figures. The new figure object copies all current view settings and gets focus in the Outline automatically. View settings maintained by a figure include: • Camera settings • Result toolbar settings • Legend configuration A figure's view settings are fully independent from the global view settings. Global view settings are maintained independently of figures. Behaviors: • If you select a figure after selecting its parent in the Outline, the graphics window transforms to the figure's stored view settings automatically (e.g. the graphics may automatically pan/zoom/rotate). • If you change the view while a figure is selected in the Outline, the figure's view settings are updated. • If you reselect the figure's parent in the Outline, the graphics window resumes the global view settings. That is, figure view settings override but do not change global view settings. • Figures always display the data of their parent object. For example, following a geometry Update and Solve, a result and its figures display different information but reuse the existing view and graphics options. Figures may be moved or copied among objects in the Outline to display different information from the same view with the same settings. • You may delete a figure without affecting its parent object. Deleting a parent object deletes all figures (and other children). Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Application Interface • In the Tree Outline (p. 3), the name of a figure defaults to simply Figure appended by a number as needed. • You may enter a caption for a figure as a string in the figure's details. It is your responsibility to maintain custom captions when copying figures.

Mechanical Hotkeys To quickly perform certain actions in Mechanical, use the following hotkeys and hotkey combinations.

Tree Outline Actions F1: opens the Mechanical User’s Guide. F2: rename a selected tree object. Ctrl + S: save the project.

Graphics Actions F6: toggles between the Shaded Exterior and Edges, Shaded Exterior, and Wireframe views (also available on the View Menu). F7: executes Zoom to Fit option (also available on the Graphics Toolbar). F8: hide selected faces. F9: hide selected bodies. Ctrl + A: selects all entities based on the active selection filter (bodies, faces, edges, vertices, nodes).

Selection Filters These selection filters are also available on the Graphics Toolbar. Ctrl Ctrl Ctrl Ctrl

+ + + +

B: activate Body selection. E: activate Edge selection. F: activate Face selection. P: activate Vertex selection.

Wizards Wizards provide a layer of assistance above the standard user interface. They are made up of tasks or steps that help you interpret and work with simulations. Conceptually, the wizards act as an agent between you and the standard user interface. Wizards include the following features: • An interactive checklist for accomplishing a specific goal • A reality check of the current simulation • A list of a variety of high-level tasks, and guidance in performing the tasks • Links to useful resources

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Wizards • A series of Callout windows which provide guidance for each step

Note Callouts close automatically, or you may click inside a Callout to close it. Wizards use hyperlinks (versus command buttons) because they generally represent links to locations within the standard user interface, to content in the help system, or to a location accessible by a standard HTML hyperlink. The status of each step is taken in context of the currently selected Tree Outline (p. 3) object. Status is continually refreshed based on the Outline state (not on an internal wizard state). As a result you may: • Freely move about the Tree Outline (p. 3) (including between branches). • Make arbitrary edits without going through the wizards. • Show or hide the wizards at any time. Wizards are docked to the right side of the standard user interface for two reasons: • The Tree Outline (p. 3) sets the context for status determination. That is, the wizards interpret the Outline rather than control it. (The user interface uses a top-down left-right convention for expressing dependencies.) • Visual symmetry is maintained. To close wizards, click the . To show/hide tasks or steps, click the section header. Options for wizards are set in the Wizard (p. 85) section of the Options dialog box under the Mechanical application. The The Mechanical Wizard (p. 123) is available for your use in the Mechanical application.

The Mechanical Wizard The Mechanical Wizard appears in the right side panel whenever you click the in the toolbar. You at the top of the panel. To show or hide the can close the Mechanical Wizard at any time by clicking sections of steps in the wizard, click the section header.

Features of the Mechanical Wizard The Mechanical Wizard works like a web page consisting of collapsible groups and tasks. Click a group title to expand or collapse the group; click a task to activate the task. When activated, a task navigates to a particular location in the user interface and displays a callout with a message about the status of the task and information on how to proceed. Activating a task may change your tab selection, cursor mode, and Tree Outline (p. 3) selection as needed to set the proper context for proceeding with the task. You may freely click tasks to explore the Mechanical application. Standard tasks WILL NOT change any information in your simulation. Callouts close automatically based on your actions in the software. Click inside a callout to close it manually.

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Application Interface Most tasks indicate a status via the icon to the left of the task name. Rest your mouse on a task for a description of the status. Each task updates its status and behavior based on the current Tree Outline (p. 3) selection and software status. Tasks are optional. If you already know how to perform an operation, you don't need to activate the task. Click the Choose Wizard task at the top of the Mechanical Wizard to change the wizard goal. For example, you may change the goal from Find safety factors to Find fatigue life. Changing the wizard goal does not modify your simulation. At your discretion, simulations may include any available feature not covered under Required Steps for a wizard. The Mechanical Wizard does not restrict your use of the Mechanical application. You may use the Mechanical Wizard with databases from previous versions of the Mechanical application. To enable the Mechanical Wizard, click

or select View> Windows> the Mechanical Wizard.

Types of the Mechanical Wizards There are wizards that guide you through the following simulations: • Safety factors, stresses and deformation • Fatigue life and safety factor • Natural frequencies and mode shapes • Optimizing the shape of a part • Heat transfer and temperatures • Magnetostatic results • Contact region type and formulation

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Steps for Using the Mechanical Application This section describes the overall workflow involved when performing any analysis in the Mechanical application. The following workflow steps are described: Create Analysis System Define Engineering Data Attach Geometry Define Part Behavior Define Connections Apply Mesh Controls and Preview Mesh Establish Analysis Settings Define Initial Conditions Applying Pre-Stress Effects for Implicit Analysis Applying Pre-Stress Effects for Explicit Analysis Apply Loads and Supports Solve Review Results Create Report (optional)

Create Analysis System There are several types of analyses you can perform in the Mechanical application. For example, if natural frequencies and mode shapes are to be calculated, you would choose a modal analysis. Each analysis type is represented by an analysis system that includes the individual components of the analysis such as the associated geometry and model properties. Most analyses are represented by one independent analysis system. However, an analysis with data transfer can exist where results of one analysis are used as the basis for another analysis. In this case, an analysis system is defined for each analysis type, where components of each system can share data. An example of an analysis with data transfer is a response spectrum analysis, where a modal analysis is a prerequisite. • To create an analysis system, expand the Standard Analyses folder in the Toolbox and drag an analysis type object “template” onto the Project Schematic. The analysis system is displayed as a vertical array of cells (schematic) where each cell represents a component of the analysis system. Address each cell by right-clicking on the cell and choosing an editing option. • To create an analysis system with data transfer to be added to an existing system, drag the object template representing the upstream analysis directly onto the existing system schematic such that red boxes enclose cells that will share data between the systems. After you up-click, the two schematics are displayed, including an interconnecting link and a numerical designation as to which cells share data. See Working through a System for more information.

Unit System Behavior When you start the Mechanical application, the unit system defaults to the same system used in the previous session. You can change this unit system, but subsequent Mechanical editors that you start Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Steps for Using the Application while the first one is open, will default to the unit system from the initial session. In the event that you change a unit system, numerical values are converted accordingly but there is no change in physical quantity.

Define Engineering Data A part’s response is determined by the material properties assigned to the part. • Depending on the application, material properties can be linear or nonlinear, as well as temperature-dependent. • Linear material properties can be constant or temperature-dependent, and isotropic or orthotropic. • Nonlinear material properties are usually tabular data, such as plasticity data (stress-strain curves for different hardening laws), hyperelastic material data. • To define temperature-dependent material properties, you must input data to define a property-versustemperature graph. • Although you can define material properties separately for each analysis, you have the option of adding your materials to a material library by using the Engineering Data tab. This enables quick access to and re-use of material data in multiple analyses. • For all orthotropic material properties, by default, the Global Coordinate System is used when you apply properties to a part in the Mechanical application. If desired, you can also apply a local coordinate system to the part. To manage materials, right-click on the Engineering Data cell in the analysis system schematic and choose Edit. See "Basics of Engineering Data" for more information.

Attach Geometry There are no geometry creation tools in the Mechanical application. You create your geometry in an external application or import an existing mesh file. Options to bring geometry into Mechanical; include: • From within Workbench using DesignModeler. See the DesignModeler Help for details on the use of the various creation tools available. • From a CAD system supported by Workbench or one that can export a file that is supported by ANSYS Workbench. See the CAD Systems section for a complete list of the supported systems. • From within Workbench using the External Model component system. This feature imports an ANSYS Mesh (.cdb) file. See the Mesh-Based Geometry section in the Specifying Geometry in the Mechanical Application Help. Before attaching geometry, you can specify several options that determine the characteristics of the geometry you choose to import. These options are: solid bodies, surface bodies, line bodies, parameters, attributes, named selections, material properties; Analysis Type (2D or 3D), allowing CAD associativity, importing coordinate systems (Import Work Points are only available in the DesignModeler application), saving updated CAD file in reader mode, “smart” refreshing of models with unmodified components, and allowing parts of mixed dimension to be imported as assembly components that have parts of

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Attach Geometry different dimensions. The availability of these options varies across the supported CAD systems. See the Geometry Preferences section for details.

Related Procedures Procedure Specifying geometry options

Condition Optional task that can be done before attaching geometry.

Procedural Steps 1. In an analysis system schematic, perform either of the following: • Right-click on the Geometry cell and choose Properties OR • Select the Geometry cell in the schematic for a standard analysis, then from the View drop-down menu, choose any option that includes Properties or Components. 2. Check boxes to specify Default Geometry Options and Advanced Geometry Defaults.

Attaching DesignModeler geometry to the Mechanical application

DesignModeler is running in an analysis system.

Double-click on the Model cell in the same analysis system schematic. The Mechanical application opens and displays the geometry.

DesignModeler is not running. Geometry is stored in an agdb file.

1. Select the Geometry cell in an analysis system schematic. 2. Browse to the agdb file from the following access points: • Right-click on the Geometry cell in the Project Schematic, Import Geometry and choose Browse. 3. Double-click on the Model cell in the schematic. The Mechanical application opens and displays the geometry.

Attaching CAD geometry to the Mechanical application

CAD system is running.

1. Select the Geometry cell in an analysis system schematic. 2. Right-click on the Geometry cell listed to select geometry for import. 3. If required, set geometry options for import into the Mechanical application by highlighting the Geometry cell and choosing settings under Preferences in the Properties Panel. 4. Double-click on the Model cell in the same analysis system schematic. The Mechanical application opens and displays the geometry.

CAD system is not running. Geometry is stored

1. Select the Geometry cell in an analysis system schematic. 2. Browse to the CAD file from the following access points:

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Steps for Using the Application Procedure

Condition in a native CAD system file, or in a CAD “neutral” file such as Parasolid or IGES.

Procedural Steps • Right-click on the Geometry cell in the Project Schematic and choose Import Geometry. 3. Double-click on the Model cell in the Project Schematic. The Mechanical application opens and displays the geometry.

CAD Interface Terminology The CAD interfaces can be run in either plug-in mode or in reader mode. • Attaching geometry in plug-in mode: requires that the CAD system be running. • Attaching geometry in reader mode: does not require that the CAD system be running.

Updating Geometry from Within the Mechanical Application You can update all geometry by selecting the Update Geometry from Source context menu option, accessible by right-clicking on the Geometry tree object or anywhere in the Geometry window. The following update options are also available: • Selective Update (p. 128) • Smart CAD Update (p. 129) Selective Update Using the Geometry object right-click menu option Update Selected Parts>Update: Use Geometry Parameter Values, you can selectively update individual parts and synchronize the Mechanical application model to the CAD model. This option reads the latest geometry and processes any other data (parameters, attributes, etc.) based on the current user preferences for that model.

Note Changes to either the number of turns or the thickness properties associated with a body do not update the CAD model. This update feature only applies parts that you select. It does not import new parts added in the CAD system following the original import or last complete update. Assembly Parameter values are always updated. In addition, this feature is not a tool for removing parts from the Mechanical application tree, however; it will remove parts which have been selected for update in WB, but that no longer exist in the CAD model if an update is successful (if at least one valid part is updated). The Update Selected Parts feature supports the associative geometry interfaces for: • DesignModeler • Autodesk Inventor

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Define Part Behavior • CATIA V5 • Creo Elements/Direct Modeling • Creo Parametric (formerly Pro/ENGINEER) • Solid Edge • NX • SolidWorks With the exception of AutoCAD, executing the selective update feature on any unsupported interface will complete a full update of the model. Smart CAD Update Using the Geometry Preferences, you enable the Smart CAD Update. Note that Geometry Preferences are supported by a limited number of CAD packages. See the Project Schematic Advanced Geometry Options table for details.

Define Part Behavior After attaching geometry, you can access settings related to part behavior by right-clicking on the Model cell in the analysis system schematic and choosing Edit .... The Mechanical application opens with the environment representing the analysis system displayed under the Model object in the tree. An Analysis Settings object is added to the tree. See the Establish Analysis Settings (p. 134) overall step for details. An Initial Condition object may also be added. See the Define Initial Conditions (p. 136) overall step for details. The Mechanical application uses the specific analysis system as a basis for filtering or making available only components such as loads, supports and results that are compatible with the analysis. For example, a Static Structural analysis type will allow only structural loads and results to be available. Presented below are various options provided in the Details view for parts and bodies following import.

Stiffness Behavior In addition to making changes to the material properties of a part, you may designate a part's Stiffness Behavior as being flexible, rigid, or as a gasket. • Setting a part’s behavior as rigid essentially reduces the representation of the part to a single point mass thus significantly reducing the solution time. • A rigid part will need only data about the density of the material to calculate mass characteristics. Note that if density is temperature dependent, density will be evaluated at the reference temperature. For contact conditions, specify Young’s modulus. • Flexible and rigid behaviors are applicable only to static structural, transient structural, rigid dynamics, explicit dynamics, and modal analyses. Gasket behavior is applicable only to static structural analyses.

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Steps for Using the Application Flexible is the default Stiffness Behavior. To change, simply select Rigid or Gasket from the Stiffness Behavior drop-down menu. Also see the Rigid Bodies (p. 401) section or the Gasket Bodies section.

Note Rigid behavior is not available for the Samcef solver.

Coordinate Systems The Coordinate Systems object and its child object, Global Coordinate System, is automatically placed in the tree with a default location of 0, 0, 0, when a model is imported. For solid parts and bodies: by default, a part and any associated bodies use the Global Coordinate System. If desired, you can apply a apply a local coordinate system to the part or body. When a local coordinate system is assigned to a Part, by default, the bodies also assume this coordinate system but you may modify the system on the bodies individually as desired. For surface bodies, solid shell bodies, and line bodies: by default, these types of geometries generate coordinates systems on a per element type basis. It is necessary for you to create a local coordinate system and associated it with the parts and/or bodies using the Coordinate System setting in the Details view for the part/body if you wish to orient those elements in a specific direction.

Reference Temperature The default reference temperature is taken from the environment (By Environment), which occurs when solving. This necessarily means that the reference temperature can change for different solutions. The reference temperature can also be specified for a body and will be constant for each solution (By Body). Selecting By Body will cause the Reference Temperature Value field to specify the reference temperature for the body. It is important to recognize that any value set By Body will only set the reference temperature of the body and not actually cause the body to exist at that temperature (unlike the Environment Temperature entry on an environment object, which does set the body's temperature).

Note Selecting By Environment can cause the body to exist at that temperature during the analysis but selecting By Body will only ever effect reference temperature. So if the environment temperature and the body have a different specification, thermal expansion effects can occur even if no other thermal loads are applied.

Note If the material density is temperature dependent, the mass that is displayed in the Details view will either be computed at the body temperature, or at 22°C. Therefore, the mass

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Define Part Behavior computed during solution can be different from the value shown, if the Reference Temperature is the Environment.

Note When nonlinear material effects are turned off, values for thermal conductivity, specific heat, and thermal expansion are retrieved at the reference temperature of the body when creating the ANSYS solver input.

Reference Frame The Reference Frame determines the analysis treatment perspective of the body for an Explicit Dynamics analysis. The Reference Frame property is available for solid bodies when an Explicit Dynamics system is part of the solution. The valid values are Langrangian (default) and Eulerian (Virtual). Eulerian is not a valid selection if Stiffness Behavior is set to Rigid.

Material Assignment Once you have attached your geometry, you can choose a material for the simulation. When you select a part in the tree outline, the Assignment entry under Material in the Details view lists a default material for the part. From the fly-out menu, you can: • Create a new material definition • Import a material • Edit the characteristics of the current material • Assign a material from the list of available materials.

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Steps for Using the Application When you edit the currently assigned material, create a material, or import a material, you work in the Engineering Data tab. Once you have completed any of those operations, you must refresh the model cell in the Project Schematic to bring new data into the Mechanical application.

Nonlinear Material Effects You can also choose to ignore any nonlinear effects from the material properties. • By default the program will use all applicable material properties including nonlinear properties such as stress-strain curve data. • Setting Nonlinear Effects to No will ignore any nonlinear properties only for that part. • This option will allow you to assign the same material to two different parts but treat one of the parts as linear. • This option is applicable only for static structural, transient structural, steady state thermal and transient thermal analyses.

Thermal Strain Effects For structural analyses, you can choose to have Workbench calculate a Thermal Strain result by setting Thermal Strain Effects to Yes. Choosing this option enables the coefficient of thermal expansion to be sent to the solver.

Cross Section When a line body is imported into the Mechanical application, the Details view displays the Cross Section field and associated cross section data. These read-only fields display the name and data assigned to the geometry in DesignModeler or the supported CAD system, if one was defined. See Line Bodies (p. 387) for further information.

Model Dimensions When you attach your geometry or model, the model dimensions display in the Details View (p. 11) in the Bounding Box sections of the Geometry or Part objects. Dimensions have the following characteristics: • Units are created in your CAD system. • ACIS and CATIA model units may be set. • Other geometry units are automatically detected and set. • Assemblies must have all parts dimensioned in the same units.

Define Connections Once you have addressed the material properties and part behavior of your model, you may need to apply connections to the bodies in the model so that they are connected as a unit in sustaining the applied loads for analysis. Available connection features are: • Contacts: defines where two bodies are in contact or a user manually defines contact between two bodies.

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Apply Mesh Controls and Preview Mesh • Joints: a contact condition in the application that is defined by a junction where bodies are joined together that has rotational and translational degrees of freedom. • Mesh Connections: used to join the meshes of topologically disconnected surface bodies that reside in different parts. • Springs: defines as an elastic element that connects two bodies or a body to “ground” that maintains its original shape once the specified forces are removed. • Bearings: are used to confine relative motion and rotation of a rotating machinery part. • Beam Connections: used to establish body to body or body to ground connections. • End Releases are used to release degrees of freedoms at a vertex shared by two or more edges of one or more line bodies. • Spot Welds: connects individual surface body parts together to form surface body model assemblies. Given the complex nature of bodies coming into contact with one another, especially if the bodies are in motion, it is recommended that you review the Connections section of the documentation.

Apply Mesh Controls and Preview Mesh Meshing is the process in which your geometry is spatially discretized into elements and nodes. This mesh along with material properties is used to mathematically represent the stiffness and mass distribution of your structure. Your model is automatically meshed at solve time. The default element size is determined based on a number of factors including the overall model size, the proximity of other topologies, body curvature, and the complexity of the feature. If necessary, the fineness of the mesh is adjusted up to four times (eight times for an assembly) to achieve a successful mesh. If desired, you can preview the mesh before solving. Mesh controls are available to assist you in fine tuning the mesh to your analysis. Refer to the Meshing Help for further details.

To preview the mesh in the Mechanical Application: See the Previewing Surface Mesh section.

To apply global mesh settings in the Mechanical Application: See the Global Mesh Controls section.

To apply mesh control tools on specific geometry in the Mechanical Application: See the Local Mesh Controls section.

To use virtual topology: All virtual topology operations in the Mechanical application are described in the Virtual Topology section of the Meshing Help.

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Steps for Using the Application

Establish Analysis Settings Each analysis type includes a group of analysis settings that allow you to define various solution options customized to the specific analysis type, such as large deflection for a stress analysis. Refer to the specific analysis types section for the customized options presented under “Preparing the Analysis”. Default values are included for all settings. You can accept these default values or change them as applicable. Some procedures below include animated presentations. Please view online if you are reading the PDF version of the help. Interface names and other components shown in the demos may differ from those in the released product. To verify/change analysis settings in the Mechanical application: 1.

Highlight the Analysis Settings object in the tree. This object was inserted automatically when you established a new analysis in the Create Analysis System (p. 125) overall step.

2.

Verify or change settings in the Details view of the Analysis Settings object. These settings include default values that are specific to the analysis type. You can accept or change these defaults. If your analysis involves the use of steps, refer to the procedures presented below.

To create multiple steps (applies to structural static, transient structural, rigid dynamics, steady-state thermal, transient thermal, magnetostatic, and electric analyses): You can create multiple steps using any one of the following methods: 1.

Highlight the Analysis Settings object in the tree. Modify the Number of Steps field in the Details view. Each additional Step has a default Step End Time that is one second more than the previous step. These step end times can be modified as needed in the Details view. You can also add more steps simply by adding additional step End Time values in the Tabular Data window. The following demonstration illustrates adding steps by modifying the Number of Steps field in the Details view.

Or 2.

Highlight the Analysis Settings object in the tree. Begin adding each step's end time values for the various steps to the Tabular Data window. You can enter the data in any order but the step end time points will be sorted into ascending order. The time span between the consecutive step end times will form a step. You can also select a row(s) corresponding to a step end time, click the right mouse button and choose Delete Rows from the context menu to delete the corresponding steps. The following demonstration illustrates adding steps directly in the Tabular Data window.

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Establish Analysis Settings Or 3.

Highlight the Analysis Settings object in the tree. Choose a time point in the Graph window. This will make the corresponding step active. Click the right mouse button and choose Insert Step from the context menu to split the existing step into two steps, or choose Delete Step to delete the step. The following demonstration illustrates inserting a step in the Graph window, changing the End Time in the Tabular Data window, deleting a step in the Graph window, and deleting a step in the Tabular Data window.

Specifying Analysis Settings for Multiple Steps 1.

Create multiple steps following the procedure ”To create multiple steps” above.

2.

Most Step Controls, Nonlinear Controls, and Output Controls fields in the Details view of Analysis Settings are “step aware”, that is, these settings can be different for each step. Refer to the table in Analysis Settings for Most Analysis Types (p. 635) to determine which specific controls are step aware (designated as footnote 2 in the table). Activate a particular step by selecting a time value in the Graph window or the Step bar displayed below the chart in the Graph window. The Step Controls grouping in the Details view indicates the active Step ID and corresponding Step End Time. The following demonstration illustrates turning on the legend in the Graph window, entering analysis settings for a step, and entering different analysis settings for another step.

If you want to specify the same analysis setting(s) to several steps, you can select all the steps of interest as follows and change the analysis settings details. • To change analysis settings for a subset of all of the steps: – From the Tabular Data window: 1. Highlight the Analysis Settings object. 2. Highlight steps in the Tabular Data window using either of the following standard windowing techniques: → Ctrl key to highlight individual steps. → Shift key to highlight a continuous group of steps. 3. Click the right mouse button in the window and choose Select All Highlighted Steps from the context menu.

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Steps for Using the Application 4. Specify the analysis settings as needed. These settings will apply to all selected steps. – From the Graph window: 1. Highlight the Analysis Settings object. 2. Highlight steps in the Graph window using either of the following standard windowing techniques: → Ctrl key to highlight individual steps. → Shift key to highlight a continuous group of steps. 3. Specify the analysis settings as needed. These settings will apply to all selected steps. • To specify analysis settings for all the steps: 1. Click the right mouse button in either window and choose Select All Steps. 2. Specify the analysis settings as needed. These settings will apply to all selected steps. The following demonstration illustrates multiple step selection using the bar in the Graph window, entering analysis settings for all selected steps, selecting only highlighted steps in the Tabular Data window, and selecting all steps.

The Worksheet for the Analysis Settings object provides a single display of pertinent settings in the Details view for all steps.

Details of various analysis settings are discussed in "Configuring Analysis Settings" (p. 635).

Define Initial Conditions This step is based upon the selected type analysis. Workbench provides you with the ability to begin your analysis with an initial condition, a link to an existing solved or associated environment, or an initial temperature. For the following analysis types, a tree object is automatically generated allowing you to define specifications. For additional information, see the individual analysis types section. 136

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Define Initial Conditions Analysis Type

Tree Object

Description

Transient Structural

Initial Condi- By default, a transient structural analysis is at rest. However, you can tions folder define velocity as an initial condition by inserting a Velocity object under the Initial Conditions folder.

Explicit Dynamics

Initial Conditions folder: Pre-Stress object

Because an explicit dynamics analysis is better suited for short duration events, preceding it with an implicit analysis may produce a more efficient simulation especially for cases in which a generally slower (or rate-independent) phenomenon is followed by a much faster event, such as the collision of a pressurized container. For an Explicit Dynamics system, the Initial Conditions folder includes a Pre-Stress object to control the transfer of data from an implicit static or transient structural analysis to the explicit dynamics analysis. Transferable data include the displacements, or the more complete Material State (displacements, velocities, stresses, strains, and temperature). See Recommended Guidelines for Pre-Stress Explicit Dynamics (p. 141) for more information. An explicit dynamics analysis is at rest by default. However, for both Explicit Dynamics and Explicit Dynamics (LS-DYNA Export) systems, you can define velocity or angular velocity as initial conditions by inserting a Velocity object or Angular Velocity object under the Initial Conditions folder.

Modal

Pre-Stress object

A Modal analysis can use the stress results from a static structural analysis to account for stress-stiffening effect. See the Modal Analysis (p. 196) section for details.

Linear Buckling

Pre-Stress object

A Linear Buckling analysis must use the stress-stiffening effects of a static structural analysis. See the Linear Buckling Analysis (p. 192) section for details.

Harmonic Response (Full)

Pre-Stress object

A Harmonic Response (Full) analysis linked to a Static Structural analysis can use the stress results to account for stress-stiffening effect.

Random Vibration, Response Spectrum, Harmonic Response MSUP (Mode Superposition) linked, or Transient (MSUP) linked

Initial Condi- A Random Vibration, Response Spectrum, Harmonic (Mode Superposition tions folder: - MSUP) linked or a Transient (MSUP) linked analysis must use the mode Modal object shapes derived in a Modal analysis.

Steady-State Thermal

Initial Temperature object

For a Steady-State Thermal analysis, you have the ability to specify an initial temperature.

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Steps for Using the Application Analysis Type

Tree Object

Description

Transient Thermal

Initial Temperature object

For a Transient Thermal analysis, the initial temperature distribution should be specified.

Note Temperatures from a steady-state thermal or transient thermal analysis can be applied to a static structural or transient structural analysis as a Thermal Condition load. Depending upon the analysis type an object is automatically added to the tree. To define an initial condition in the Mechanical application: • For a Transient Structural analysis, use the Initial Conditions object to insert Velocity. For an Explicit Dynamics analysis, use the Initial Conditions object to insert Velocity, Angular Velocity. These values can be scoped to specific parts of the geometry. • For a Harmonic Response, Modal, Linear Buckling, or Explicit Dynamics analysis, use the Details view of the Pre-Stress object to define the associated Pre-Stress Environment. For an Explicit Dynamics analysis, use the Details view of this object to select either Material State (displacements, velocities, strains and stresses) or Displacements only modes, as well as the analysis time from the implicit analysis which to obtain the initial condition. For Displacements only, a Time Step Factor may be specified to convert nodal DOF displacements in the implicit solution into constant velocities for the explicit analysis according to the following expression: Velocity = Implicit displacement/(Initial explicit time step x time step factor)

Note The Displacements only mode is applicable only to results from a linear, static structural analysis.

• For a Random Vibration or Response Spectrum analysis, you must point to a modal analysis using the drop-down list of the Modal Environment field in the Details view. • For the Steady-State and Transient Thermal analyses, use the Details of the Initial Temperature object to scope the initial temperature value. For a Transient Thermal analysis that has a non-uniform temperature, you need to define an associated Initial Temperature Environment. • The Details view of the Modal (Initial Conditions) object for linked Mode Superposition Harmonic and Mode Superposition Transient analyses displays the name of the pre-stress analysis system in the PreStress Environment field, otherwise the field indicates None.

Applying Pre-Stress Effects for Implicit Analysis Mechanical leverages the power of linear perturbation technology for all pre-stress analyses performed within Mechanical. This includes pre-stress Modal analyses, Full Harmonic Response analysis using a Pre-Stressed Structural System analyses, as well as Linear Buckling analyses. The following features are available that are based on this technology: 138

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Applying Pre-Stress Effects for Implicit Analysis • Large deflection static analysis followed by pre-stress modal analysis. Thus the static analysis can be linear or nonlinear including large deflection effects.

Note – If performing a pre-stress modal analysis, it is recommended that you always include large deflection effects to produce accurate results in the modal analysis. – Pre-stress results should always originate from the same version of the application as that of the modal solution. – Although the modal results (including displacements, stresses, and strains) will be correctly calculated in the modal analysis, the deformed shape picture inside Mechanical will be based on the initial geometry, not the deformed geometry from the static analysis. If you desire to see the mode shapes based on the deformed geometry, you can take the result file into Mechanical APDL.

• True contact status as calculated at the time in the static analysis from which the eigen analysis is based. • Support for cyclic analysis. • Support for multiple result sets in the static analysis. For a pre-stressed eigen analysis, you can insert a Commands object beneath the Pre-Stress initial conditions object. The commands in this object will be executed just before the first solve for the prestressed modal analysis.

Pressure Load Stiffness If the static analysis has a pressure load applied “normal to” faces (3D) or edges (2-D), this could result in an additional stiffness contribution called the “pressure load stiffness” effect. This effect plays a significant role in linear buckling analyses. Different buckling loads may be predicted from seemingly equivalent pressure and force loads in a buckling analysis because in the Mechanical application a force and a pressure are not treated the same. As with any numerical analysis, we recommend that you use the type of loading which best models the in-service component. For more information, see the Mechanical APDL Theory Reference, under Structures with Geometric Nonlinearities> Stress Stiffening> Pressure Load Stiffness.

Restarts from Multiple Result Sets A property called Pre-Stress Define By is available in the Details view of the Pre-Stress object in the eigen analysis. It is set to Program Controlled by default which means that it uses the last solve point available in the parent static structural analysis as the basis for the eigen analysis. There are three more read only properties defined in the Details view of the Pre-Stress object – Reported Loadstep, Reported Substep and Reported Time which are set to Last, Last, and End Time or None Available by default depending on whether or not there are any restart points available in the parent static structural analysis. These read only properties show the actual load step, sub step and time used as the basis for the eigen analysis. You can change Pre-Stress Define By to Load Step, and then another property called Pre-Stress Loadstep will appear in the Details view. Pre-Stress Loadstep gives you an option to start from any Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Steps for Using the Application load step in the static structural analysis. If you use this property, then Mechanical will always pick the last substep available in that load step. You can see the actual reported substep and time as read only properties. The input value of load step should be less than or equal to the number of load steps in the parent static structural analysis. Loadstep 0 stands for the last load step available. You can change Pre-Stress Define By to Time, and then another property called Pre-Stress Time will appear in the Details view. Pre-Stress Time gives you an option to start from any time in the static structural analysis. If there is no restart point available at the time of your input, then Mechanical will pick the closest restart point available in the static structural analysis. You can see the actual reported load step, sub step and time as read only properties. The input value of time should be non-negative and it should be less than the end time of parent static structural analysis. Time 0 stands for end time of the parent analysis. If there is no restart point available in the input loadstep and the number of restart points in the parent analysis is not equal to zero, then the following error message appears: “There is no restart point available at the requested loadstep. Please change the restart controls in the parent static structural analysis to use the requested loadstep.”

Note If you use Pre-Stress Time, then Mechanical will pick the closest restart point available. It may not be the last sub step of a load step; and if it is some intermediate substep in a load step, then the result may not be reproducible if you make any changes in the parent static structural analysis or you solve it again. If there is no restart point available in the parent static structural analysis, then Reported Loadstep, Reported Substep and Reported Time are set to None Available regardless of the user input of LoadStep/Time but these will be updated to correct values once the analysis is solved with the correct restart controls for the parent structural analysis.

Contact Status You may choose contact status for the pre-stressed eigen analysis to be true contact status, force sticking, or force bonded. A property called Contact Status is available in the Details view of the PreStress object in the eigen analysis. This property controls the CONTKEY field of the Mechanical APDL PERTURB command. • Use True Status (default): Uses the current contact status from the restart snapshot. If the previous run for parent static structural is nonlinear, then the nonlinear contact status at the point of restart is frozen and used throughout the linear perturbation analysis. • Force Sticking: Uses sticking contact stiffness for the frictional contact pairs, even when the status is sliding (that is, the no sliding status is allowed). This option only applies to contact pairs whose frictional coefficient is greater than zero. • Force Bonding: Uses bonded contact stiffness and status for contact pairs that are in the closed (sticking/sliding) state.

Applying Pre-Stress Effects for Explicit Analysis Because an explicit dynamics analysis is better suited for short duration events, preceding it with an implicit analysis may produce a more efficient simulation especially for cases in which a generally slower (or rate-independent) phenomenon is followed by a much faster event, such as the collision of a pressurized container. To produce this combination, you can define pre-stress as an initial condition in an 140

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Applying Pre-Stress Effects for Explicit Analysis Explicit Dynamics system, specifying the transfer of either displacements only or the more complete Material State (displacements, velocities, stresses, and strains), from a static or transient structural analysis to an explicit dynamics analysis. Characteristics of the implicit to explicit pre-stress feature: • Applicable to 3-D analyses only. • The Material State mode, for mapping stresses, plastic strains, displacements, and velocities is valid for solid models only. • The displacements only mode is valid for solid, shell, and beam models. • The same mesh is required for both implicit and explicit analyses and only low order elements are allowed. If high order elements are used, the solve will be blocked and an error message will be issued. • For a nonlinear implicit analysis, the Strain Details view property in the Output Controls category under the Analysis Settings object must be set to Yes because plastic strains are needed for the correct results.

Recommended Guidelines for Pre-Stress Explicit Dynamics The following guidelines are recommended when using pre-stress with an Explicit Dynamics analysis: • Lower order elements must be used in the static or transient structural analysis used to pre-stress the Explicit Dynamics analysis. To do so, set the Mesh object property, Element Midside Nodes (Advanced category), to Dropped. • On the Brick Integration Scheme of all relevant bodies, use the Reduced option, to provide the most consistent results between the Static Structural or Transient Structural system and the Explicit Dynamics system. Such a selection amounts to a single integration point per lower order solid element. • For models containing Line or Surface bodies, the data transfer is limited to displacements only. In this mode, under Analysis Settings, the Static Damping option (under Damping) should be used to remove any dynamic oscillations in the stress state due to the imposed static displacements. • The temperature state is also transferred to the Explicit Dynamics analysis. The Unit System is taken care of automatically, and Internal Energy due to difference in temperature will be added to each element based on: Einternal = Einternal + Cp(T-Tref) Where: Cp = specific heat coefficient Tref = room temperature Note that stresses may still dissipate because the thermal expansion coefficient is not taken into account in the Explicit Dynamics analysis. Example - Drop Test on Pressurized Container:

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Pre-stress condition:

Transient stress distribution during drop test:

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Apply Loads and Supports

Pre-Stress Object Properties Mode Displacement Node-based displacements from a static analysis are used to initialize the explicit node positions. These displacements are converted to constant node-based velocities and applied for a pre-defined time in order to obtain the required displaced coordinates. During this times, element stresses and strains are calculated as normal by the explicit solver. Once the displaced node positions are achieved, all node-based velocities are set to 0 and the solution is completely initialized. This option is applicable to unstructured solids (hexahedral and tetrahedral), shells, and beams. Time Step Factor The initial time step from the explicit solution is multiplied by the time step factor. The resulting time is used with the nodal displacements from the ANSYS Mechanical analysis to calculate constant nodal velocities. These nodal velocities are applied to the explicit model over the resulting time in order to initialize the explicit nodes to the correct positions. Material State Node-based displacements, element stresses and strains, and plastic strains and velocities from an implicit solution are used to initialize an explicit analysis at cycle 0. This option is applicable to results from a linear static structural, nonlinear static structural, or transient dynamic Mechanical system. The ANSYS solution may be preceded with a steady-state thermal solution in order to introduce temperature differences into the solution. In this case, the accompanying thermal stresses due to the thermal expansion coefficient will be transferred but may dissipate since the thermal expansion coefficient is not considered in an explicit analysis. This option is only applicable to unstructured solid elements (hexahedral and tetrahedral). Pressure Initialization From Deformed State The pressure for an element is calculated from its compression, which is determined by the initial displacement of the element’s nodes. This is the default option and should be used for almost all implicit-explicit analyses. From Stress State The pressure for an element is calculated from the direct stresses imported from the implicit solution. This option is only available for materials with a linear equation of state. If the pressure for an element is already initialized, this calculation will be ignored. This is for a prestress analysis from an implicit solution that has been initialized from an INISTATE command and has an .rst file with all degrees of freedom fixed. Time The time at which results are extracted from the implicit analysis.

Apply Loads and Supports You apply loads and support types based on the type of analysis. For example, a stress analysis may involve pressures and forces for loads, and displacements for supports, while a thermal analysis may involve convections and temperatures. Loads applied to static structural, transient structural, rigid dynamics, steady-state thermal, transient thermal, magnetostatic, electric, and thermal-electric analyses default to either step-applied or ramped. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Steps for Using the Application That is, the values applied at the first substep stay constant for the rest of the analysis or they increase gradually at each substep. Load

Load

Full value applied

Substep Load step

at first substep 1

1 Final load value

2

2

Time (a) Stepped loads

Time (b) Ramped loads

You can edit the table of load vs. time and modify this behavior as needed. By default you have one step. However you may introduce multiple steps at time points where you want to change the analysis settings such as the time step size or when you want to activate or deactivate a load. An example is to delete a specified displacement at a point along the time history. You do not need multiple steps simply to define a variation of load with respect to time. You can use tables or functions to define such variation within a single step. You need steps only if you want to guide the analysis settings or boundary conditions at specific time points. When you add loads or supports in a static or transient analysis, the Tabular Data and Graph windows appear. You can enter the load history, that is, Time vs Load tabular data in the tabular data grid. Another option is to apply loads as functions of time. In this case you will enter the equation of how the load varies with respect to time. The procedures for applying tabular or function loads are outlined under the Defining Boundary Condition Magnitude (p. 848) section.

Note • You can also import or export load histories from or to any pre-existing libraries. • If you have multiple steps in your analysis, the end times of each of these steps will always appear in the load history table. However you need not necessarily enter data for these time points. These time points are always displayed so that you can activate or deactivate the load over each of the steps. Similarly the value at time = 0 is also always displayed. • If you did not enter data at a time point then the value will be either a.) a linearly interpolated value if the load is a tabular load or b.) an exact value determined from the function that defines the load. An “=” sign is appended to such interpolated data so you can differentiate between the data that you entered and the data calculated by the program as shown in the example below. Here the user entered data at Time = 0 and Time = 5. The value at Time = 1e-3, the end time of step 1, is interpolated.

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Solve

To apply loads or supports in the Mechanical Application: See the "Setting Up Boundary Conditions" (p. 691) section.

Solve The Mechanical application uses the same solver kernels that ANSYS Mechanical APDL (MAPDL) uses. At the Solve step, Mechanical passes its data to the appropriate MAPDL solver kernel, based on the type of analysis to be performed. That kernel then passes the solution data back to Mechanical, where you are able to look at the results. Because the same solver kernels are used, you will obtain the same results from Mechanical that you would if doing the same analysis in MAPDL. Based on the analysis type, the following solvers are available in Mechanical: • Mechanical ANSYS Parametric Design Language (MAPDL) Solver. • ANSYS Rigid Dynamics Solver: only available for Rigid Dynamics Analysis. • LS-DYNA Solver: only available for Explicit Dynamics analysis. • Explicit Dynamics Solver (AUTODYN): only available for Explicit Dynamics analysis. • Samcef Solver: only available for Static Structural and Modal analyses. You can execute the solution process on your local machine or on a remote machine such as a powerful server you might have access to. The Remote Solve Manager (RSM) feature allows you to perform solutions on a remote machine. Once completed, results are transferred to your local machine for post processing. Refer to the Solve Modes and Recommended Usage section for more details.

Solution Progress Since nonlinear or transient solutions can take significant time to complete, a status bar is provided that indicates the overall progress of solution. More detailed information on solution status can be obtained from the Solution Information object which is automatically inserted under the Solution folder for all analyses. The overall solution progress is indicated by a status bar. In addition you can use the Solution Information object which is inserted automatically under the Solution folder. This object allows you to i) view the actual output from the solver, ii) graphically monitor items such as convergence criteria for nonlinear problems and iii) diagnose possible reasons for convergence difficulties by plotting Newton-Raphson residuals. Additionally you can also monitor some result items such as displacement or temperature at a vertex or contact region’s behavior as the solution progresses.

Solve References for the Mechanical Application See the "Understanding Solving" (p. 1023) section for details on the above and other topics related to solving. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Review Results The analysis type determines the results available for you to examine after solution. For example, in a structural analysis, you may be interested in equivalent stress results or maximum shear results, while in a thermal analysis, you may be interested in temperature or total heat flux. The "Using Results" (p. 857) section lists various results available to you for postprocessing. To add result objects in the Mechanical application: 1.

Highlight a Solution object in the tree.

2.

Select the appropriate result from the Solution context toolbar or use the right-mouse click option.

To review results in the Mechanical application: 1.

Click on a result object in the tree.

2.

After the solution has been calculated, you can review and interpret the results in the following ways: • Contour results - Displays a contour plot of a result such as stress over geometry. • Vector Plots - Displays certain results in the form of vectors (arrows). • Probes - Displays a result at a single time point, or as a variation over time, using a graph and a table. • Charts - Displays different results over time, or displays one result against another result, for example, force vs. displacement. • Animation - Animates the variation of results over geometry including the deformation of the structure. • Stress Tool - to evaluate a design using various failure theories. • Fatigue Tool - to perform advanced life prediction calculations. • Contact Tool - to review contact region behavior in complex assemblies. • Beam Tool - to evaluate stresses in line body representations.

Note Displacements of rigid bodies are shown correctly in transient structural and rigid dynamics analyses. If rigid bodies are used in other analyses such as static structural or modal analyses, the results are correct, but the graphics will not show the deformed configuration of the rigid bodies in either the result plots or animation.

Note If you resume a Mechanical model from a project or an archive that does not contain result files, then results in the Solution tree can display contours but restrictions apply: • The result object cannot show a deformed shape; that is, the node-based displacements are not available to deform the mesh.

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Create Report (optional) • The result object cannot animate. • Contours are not available for harmonic results that depend upon both real and imaginary result sets.

See the "Using Results" (p. 857) section for more references on results.

Create Report (optional) Workbench includes a provision for automatically creating a report based on your entire analysis. The documents generated by the report are in HTML. The report generates documents containing content and structure and uses an external Cascading Style Sheet (CSS) to provide virtually all of the formatting information.

Report References for the Mechanical Application See the Report Preview (p. 22) section.

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Analysis Types You can perform several types of analyses in the Mechanical application using pre-configured analysis systems (see Create Analysis System (p. 125)). For doing more advanced analysis you can use Commands objects in the Mechanical interface. This allows you to enter sMechanical APDL application commands in the Mechanical application to perform the analysis. If you are familiar with the Mechanical APDL application commands, you will have the capability of performing analyses and techniques that are beyond those available using the analysis systems in Workbench. This section describes the following analysis types that you can perform in the Mechanical interface. Available features can differ from one solver to another. Each analysis section assumes that you are familiar with the nature and background of the analysis type as well as the information presented in the "Steps for Using the Mechanical Application" (p. 125) section. Design Assessment Analysis Electric Analysis Explicit Dynamics Analysis Linear Dynamic Analysis Types Magnetostatic Analysis Rigid Dynamics Analysis Static Structural Analysis Steady-State Thermal Analysis Thermal-Electric Analysis Transient Structural Analysis Transient Structural Analysis Using Linked Modal Analysis System Transient Thermal Analysis Special Analysis Topics

Design Assessment Analysis Introduction The Design Assessment system enables the selection and combination of upstream results and the ability to optionally further assess results with customizable scripts. Furthermore it enables the user to associate attributes, which may be geometry linked but not necessarily a property of the geometry, to the analysis via customizable items that can be added in the tree. Finally, custom results can be defined from the script and presented in the Design Assessment system to enable complete integration of a post finite element analysis process. The scripting language supported is python based. The location of the script and the available properties for the additional attributes and results can be defined via an XML file which can be easily created in any text editor and then selected by right clicking on the Setup cell on the system. The Design Assessment system must be connected downstream of another analysis system (the allowed system types are listed below in Preparing the Analysis). An Assessment Type must be set for each Design Assessment system. Predefined scripts are supplied to interface with the BEAMCHECK and FATJACK products. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Analysis Types

Points to Remember • The BEAMCHECK and FATJACK assessment types are not available on Linux. • Design Assessment is not supported on the SUSE 10 x64 platform.

Preparing the Analysis Create Analysis System Basic general information about this topic ... for this analysis type: Because a design assessment analysis is a postprocessing analysis, one or more upstream analysis systems (at this time, limited to Static Structural, Transient Structural, Harmonic Response, Modal, Response Spectrum, Random Vibration, and Explicit Dynamics systems) are a required prerequisite. The requirement then is for two or more analysis systems, including a Design Assessment analysis system, that share resources, geometry, and model data. From the Toolbox, drag one of the allowed system templates to the Project Schematic. Then, drag a Design Assessment template directly onto the first template, making sure that all cells down to and including the Model cell are shared. If multiple upstream systems are included, all must share the cells above and including the Model cell. Define Engineering Data Basic general information about this topic ... for this analysis type: There are no specific considerations for a design assessment analysis. Attach Geometry Basic general information about this topic ... for this analysis type: There are no specific considerations for a design assessment analysis. Define Part Behavior Basic general information about this topic ... for this analysis type: There are no specific considerations for a design assessment analysis. Define Connections Basic general information about this topic

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Design Assessment Analysis ... for this analysis type: There are no specific considerations for a design assessment analysis. Apply Mesh Controls/Preview Mesh Basic general information about this topic ... for this analysis type: There are no specific considerations for a design assessment analysis. Establish Analysis Settings Basic general information about this topic ... for this analysis type: There are no specific considerations for a design assessment analysis. Define Initial Conditions Basic general information about this topic ... for this analysis type: You must point to a structure analysis in the Initial Condition environment field. Apply Loads and Supports Basic general information about this topic ... for this analysis type: There are no specific considerations for a design assessment analysis. Solve Basic general information about this topic ... for this analysis type: Solution Information continuously updates any listing output from the Design Assessment log files and provides valuable information on the behavior of the structure during the analysis. The file solve.out is provided for log information from any external process your analysis may use. Solve script and Evaluate script log files are produced by the solve and evaluate Python processes respectively. Select the log information that you want to display from the Solution Output drop down. Review Results Basic general information about this topic

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Analysis Types ... for this analysis type: The following Mechanical results are available when Solution Combination is enabled for the design assessment analysis: • Stress Tool • Fatigue Tool • Contact Tool (for the following contact results: Frictional Stress, Penetration, Pressure, and Sliding Distance) • Beam Tool • Beam Results • Stresses • Elastic Strains • Deformations The results available for insertion will depend on the types of the systems selected for combination and the setting of the Results Availability field in the Details panel of the Design Assessment Solution object in the tree. In addition, DA Result objects will be available if they are enabled for the design assessment analysis.

Note Not all of the standard right-click menu options are available for DA Result objects. Cut, Copy, Paste, Copy to Clipboard, Duplicate, Rename, and Export are removed.

Electric Analysis Introduction An electric analysis supports Steady-State Electric Conduction. Primarily, this analysis type is used to determine the electric potential in a conducting body created by the external application of voltage or current loads. From the solution, other results items are computed such as conduction currents, electric field, and joule heating. An Electric Analysis supports single and multibody parts. Contact conditions are automatically established between parts. In addition, an analysis can be scoped as a single step or in multiple steps. An Electric analysis computes Joule Heating from the electric resistance and current in the conductor. This joule heating may be passed as a load to a Thermal analysis simulation using an Imported Load if the Electric analysis Solution data is to be transferred to Thermal analysis. Similarly, an electric analysis can accept a Thermal Condition from a thermal analysis to specify temperatures in the body for material property evaluation of temperature-dependent materials.

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Electric Analysis

Points to Remember A steady-state electric analysis may be either linear (constant material properties) or nonlinear (temperature dependent material properties). Additional details for scoping nonlinearities are described in the Nonlinear Controls section. Once an Electric Analysis is created, Voltage and Current loads can be applied to any conducting body. For material properties that are temperature dependent, a temperature distribution can be imported using the Thermal Condition option. In addition, equipotential surfaces can be created using the Coupling Condition load option.

Preparing the Analysis Create Analysis System Basic general information about this topic ... for this analysis type: From the Toolbox, drag the Electric template to the Project Schematic. Define Engineering Data Basic general information about this topic ... for this analysis type: When an Emag license is being used only the following material properties are allowed: Isotropic Resistivity, Orthotropic Resistivity, Relative Permeability, Relative Permeability (Orthotropic), Coercive Force & Residual Induction, B-H Curve, B-H Curve (Orthotropic), Demagnetization B-H Curve. You may have to turn the filter off in the Engineering Data tab to suppress or delete those material properties/models which are not supported for this license. Attach Geometry Basic general information about this topic ... for this analysis type: Note that 3D shell bodies and line bodies are not supported in an electric analysis. Define Part Behavior Basic general information about this topic ... for this analysis type: There are no specific considerations for an electric analysis. Define Connections

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Analysis Types Basic general information about this topic ... for this analysis type: In an electric analysis, only bonded, face-face contact is valid. Any joints or springs are ignored. For perfect conduction across parts, use the MPC formulation. To model contact resistance, use Augmented Lagrange or Pure Penalty with a defined Electric Conductance. Apply Mesh Controls/Preview Mesh Basic general information about this topic ... for this analysis type: Only higher order elements are allowed for an electric analysis. Establish Analysis Settings Basic general information about this topic ... for this analysis type: For an electric analysis, the basic controls are: Step Controls (p. 635): used to specify the end time of a step in a single or multiple step analysis. Multiple steps are needed if you want to change load values, the solution settings, or the solution output frequency over specific steps. Typically you do not need to change the default values. Output Controls (p. 658) allow you to specify the time points at which results should be available for postprocessing. A multi-step analysis involves calculating solutions at several time points in the load history. However you may not be interested in all of the possible results items and writing all the results can make the result file size unwieldy. You can restrict the amount of output by requesting results only at certain time points or limit the results that go onto the results file at each time point. Analysis Data Management (p. 664) settings. Define Initial Conditions Basic general information about this topic ... for this analysis type: There is no initial condition specification for an Electric analysis. Apply Loads and Supports Basic general information about this topic ... for this analysis type:

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Explicit Dynamics Analysis The following loads are supported in a Steady-State Electric analysis: • Voltage • Current • Coupling Condition (Electric) • Thermal Condition Solve Basic general information about this topic ... for this analysis type: The Solution Information object provides some tools to monitor solution progress. Solution Output continuously updates any listing output from the solver and provides valuable information on the behavior of the model during the analysis. Any convergence data output in this printout can be graphically displayed as explained in the Solution Information section. Review Results Basic general information about this topic ... for this analysis type: Applicable results are all electric result types. Once a solution is available, you can contour the results or animate the results to review the responses of the model. For the results of a multi-step analysis that has a solution at several time points, you can use probes to display variations of a result item over the steps. You may also wish to use the Charts feature to plot multiple result quantities against time (steps). For example, you could compare current and joule heating. Charts can also be useful when comparing the results between two analysis branches of the same model.

Explicit Dynamics Analysis Introduction You can perform a transient explicit dynamics analysis in the Mechanical application using an Explicit Dynamics system. Additionally, the Explicit Dynamics (LS-DYNA Export) system is available to export the model in LS-DYNA .k file format for subsequent analysis with the LS-DYNA solver. Unless specifically mentioned otherwise, this section addresses both the Explicit Dynamics and Explicit Dynamics (LS-DYNA Export) systems. Special conditions for the Explicit Dynamics (LS-DYNA Export) system are noted where pertinent.

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Analysis Types An explicit dynamics analysis is used to determine the dynamic response of a structure due to stress wave propagation, impact or rapidly changing time-dependent loads. Momentum exchange between moving bodies and inertial effects are usually important aspects of the type of analysis being conducted. This type of analysis can also be used to model mechanical phenomena that are highly nonlinear. Nonlinearities may stem from the materials, (for example, hyperelasticity, plastic flows, failure), from contact (for example, high speed collisions and impact) and from the geometric deformation (for example, buckling and collapse). Events with time scales of less than 1 second (usually of order 1 millisecond) are efficiently simulated with this type of analysis. For longer time duration events, consider using a Transient Structural Analysis (p. 285) system. This section contains the following topics: Using Explicit Dynamics to Define Initial Conditions for Implicit Analysis

Points to Remember An explicit dynamics analysis typically includes many different types of nonlinearities including large deformations, large strains, plasticity, hyperelasticity, material failure etc. The time step used in an explicit dynamics analysis is constrained to maintain stability and consistency via the CFL condition, that is, the time increment is proportional to the smallest element dimension in the model and inversely proportional to the sound speed in the materials used. Time increments are usually on the order of 1 microsecond and therefore thousands of time steps (computational cycles) are usually required to obtain the solution. • Explicit dynamics analyses only support the mm, mg, ms solver unit system. This will be extended to support more unit systems in a future release. • 2-D Explicit Dynamics analyses are supported for Plane Strain and Axisymmetric behaviors. • When attempting to use the Euler capabilities in the Explicit Dynamics analysis system, the following license restrictions are observed: – Set-up and solve of Euler capabilities in the Explicit Dynamics system are supported for the full ANSYS Autodyn (acdi_ad3dfull) license. – Set-up but not solve of Euler capabilities in the Explicit Dynamics system are supported for the pre-post ANSYS Autodyn (acdi_prepost) license. – Set-up or solve of Euler capabilities in the Explicit Dynamics system are not supported for the ANSYS Explicit STR (acdi_explprof ) license. – Euler capabilities are not supported for the Explicit Dynamics (LS-DYNA Export) system. • (Linux only) In order to run a distributed solution on Linux, you must add the MPI_ROOT environment variable and set it to the location of the MPI software installation. It should be of the form: {ANSYS installation}/commonfiles/MPI/Platform/{version}/{platform} For example: usr/ansys_inc/v150/commonfiles/MPI/Platform/9.1/linx64 • Consideration should be given to the number of elements in the model and the quality of the mesh to give larger resulting time steps and therefore more efficient simulations. • A coarse mesh can often be used to gain insight into the basic dynamics of a system while a finer mesh is required to investigate nonlinear material effects and failure. 156

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Explicit Dynamics Analysis • The quality of the solution can be monitored by reviewing momentum and energy conservation graphs in the solution output. Low energy errors (Write Input File... – In the Save As dialog box, specify a location and name for the input file • Start the coupling service and obtain the following information from the System Coupling Server (SCS) file: – the port and host on which the service is being run, and – the identifier (or name) for Mechanical • Use this SCS information to set the Mechanical–specific system coupling command line options (described in Starting an ANSYS Session from the Command Level in the Operations Guide). • Note that for System Coupling cases run on Linux, when you launch MAPDL from the command line, you need to be careful about the participant name that you use. You may need to escape the quotes or the space if a name with a space, such as "Solution 1", is used for MAPDL. For example, appropriate text in the command line is:

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Special Analysis Topics – ansys150.exe -scname=\"Solution 1\" or – ansys150.exe -scname="Solution\ 1"

Troubleshooting Two-Way Coupling Analysis Problems The following files, found in the Mechanical run directory (SYS/MECH under a Workbench design point directory), may prove useful in troubleshooting coupled analysis problems: • file.err: This file contains a summary of all of the errors that occurred during the run. • solve.out (or other output file): This file contains a complete summary of the current/latest run's evolution. This is one of the most useful files to determine why the coupled analysis failed. To generate extensive debug output during the analysis, enter the following command as a command snippet in the analysis branch when completing the Mechanical problem setup: /debug,-1,,,,,2

Provide all of these files when submitting a request for service to ANSYS personnel.

Product Licensing Considerations when using System Coupling The licenses needed for Mechanical as part of a System Coupling analyses are listed in the table below. Additional licenses may be required for other participant systems in the coupled analysis, but no additional licenses are required for the System Coupling infrastructure itself. The simultaneous execution of coupling participants currently precludes the use of the license sharing feature that exists for some product licenses. The following specific requirements consequently exist: • Distinct licenses are required for each coupling participant. • Licensing preferences should be set to ‘Use a separate license for each application’ rather than ‘Share a single license between applications when possible.’ The requirements listed above are particularly relevant for ANSYS Academic products. Table 2: Licenses required for Mechanical as part of a System Coupling analysis System

Commercial License Required

Academic License Required

Static Structural or Transient Structural

• ANSYS Structural,

• ANSYS Academic Associate,

• ANSYS Mechanical,

• ANSYS Academic Research,

• ANSYS Mechanical CFD-Flo,

• ANSYS Academic Research Mechanical,

• ANSYS Mechanical Emag, • ANSYS Multiphysics, • ANSYS Structural Solver, • ANSYS Mechanical Solver, or

• ANSYS Academic Teaching Advanced, • ANSYS Academic Teaching Introductory, or • ANSYS Academic Teaching Mechanical

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Analysis Types System

Commercial License Required

Academic License Required

• ANSYS Multiphysics Solver Steady-State Thermal or Transient Thermal

• ANSYS Mechanical,

• ANSYS Academic Associate,

• ANSYS Mechanical CFD-Flo,

• ANSYS Academic Research,

• ANSYS Mechanical Emag,

• ANSYS Academic Research Mechanical,

• ANSYS Multiphysics, • ANSYS Structural Solver,

• ANSYS Academic Teaching Advanced,

• ANSYS Mechanical Solver, or

• ANSYS Academic Teaching Introductory, or

• ANSYS Multiphysics Solver

• ANSYS Academic Teaching Mechanical

Thermal-Stress Analysis The Mechanical application allows you to apply temperatures from a thermal analysis as loads in a structural analysis for thermal stress evaluations. The load transfer is applicable for cases when the thermal and structural analyses share the mesh as well as for cases when the two analyses are solved using different meshes. For cases when the meshes are different, the temperature values are mapped and interpolated between the source and target meshes. Workflow for performing a thermal stress analysis with: • Shared Model 1. From the toolbox, drag and drop a transient or steady-state thermal template onto the project schematic. Perform all steps to set up a Steady-State Thermal or Transient Thermal. Specify mesh controls, boundary conditions, and solution settings as you normally would and solve the analysis. 2. Drag and drop a Static Structural or Transient Structural template on top of the thermal systems solution cell to enable the data transfer.

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Special Analysis Topics 3. Double-click the structural systems Setup cell. In the Mechanical application an Imported Body Temperature load is automatically added into the structural system's tree under an Imported Load folder. 4. Select appropriate geometry in the Details view of the Imported Body Temperature object using the Geometry or Named Selection scoping option. If the load is scoped to one or more surface bodies, the Shell Face option in the details view allows you to apply the temperatures to Both faces, to the Top face(s) only, or to the Bottom face(s) only. See Imported Body Temperature for additional information. 5. Change any of the columns in the Data View tab as needed: – Source Time - The time at which the data will be imported from the coarse analysis. – Analysis Time - Choose the analysis time at which the load will be applied.

Note The Data View can automatically be populated with the source and analysis times using Source Time property in the Details view. Use All to import data at all times in the source analysis, or Range to import data for a range specified by a Minimum and a Maximum.

6. Right-click the Imported Body Temperature object and click Import Load to import the load. When the load has been imported successfully, a contour plot of the temperatures will be displayed in the Geometry window.

Note The range of data displayed in the graphics window can be controlled using the Legend controls options. See Imported Boundary Conditions for additional information.

7. You can define multiple rows in the Data View tab to import source data at multiple times and apply them at different analysis. If multiple rows are defined in the Data View, it is possible to preview imported load vectors/contour applied to a given row or analysis time in the Data View. Choose Active Row or Analysis Time using the By property under Graphics Controls in the details of the imported load and then specify the Active Row/Analysis Time to preview the data.

Note If the Analysis Time specified by the user does not match the list of analysis times in the Data View, the data is displayed at the analysis time closest to the specified time.

• Unshared Model 1. From the toolbox, drag and drop a steady-state or transient thermal template onto the project schematic. Perform all steps to set up a Steady-State Thermal or Transient Thermal. Specify mesh controls, boundary conditions, and solution settings as you normally would and solve the analysis.

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Analysis Types 2. Drag and drop a Static Structural or Transient Structural template onto the project schematic. Share the Engineering Data and Geometry cells if required and then drag the Solution cell of the thermal system onto the Setup cell of the structural system.

3. Double-click the structural systems Setup cell. In the Mechanical application, an Imported Body Temperature load is automatically added into the structural system's tree under an Imported Load folder. 4. Select appropriate geometry in the Details view of the Imported Body Temperature object using the Geometry or Named Selection scoping option. If the load is scoped to one or more surface bodies, the Shell Face option in the details view allows you to apply the temperatures to Both faces, to the Top face(s) only, or to the Bottom face(s) only. See Imported Body Temperature for additional information.

Note In a 3D analysis, if the Triangulation mapping algorithm is used, the Transfer Type mapping option defaults to Surface when the load is scoped to shell bodies.

5. The Source Bodies option in the Details view allows you to select the bodies, from the thermal analysis, that make up the source mesh for mapping the data. You can choose one of the following options: – Automatic- Heuristics based on the geometry are used to automatically match source and target bodies and map temperature values. A source body is matched with a target body if it satisfies the below criteria. a. The percent volume difference is within the user defined tolerance. b. The distance between the centroid locations divided by the diagonal of the bounding box is within the user defined tolerance. The percent tolerance values can be specified in the Tolerance field. The default is set at 1%. The matching process is done in increments of 0.1 of the tolerance value, up to the defined tolerance. The process fails if multiple source bodies are found to match a target body or if no match is found for a target body. After the import is completed, a Load Transfer Summary is displayed as a comment object in the particular load branch. The summary shows the matched

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Special Analysis Topics source and target bodies as well as the values that were used to determine the match. It is recommended that you verify the import using this information.

Important This option requires the element volume results to be present in the thermal results file. Make sure that the Calculate Thermal Flux or the General Miscellaneous Details view property under the Analysis Settings object in the thermal analysis is set to Yes, so that this result is available.

Note This option is not allowed when scoped to a node-based Named Selection as the heuristic is geometry based.

– All- The source mesh in this case will comprise of all the bodies that were used in thermal analysis. For cases where the temperature values are significantly different at the boundaries across two or more bodies, this option could result in mapped target values that are generated by taking a weighted average of the source values across multiple bodies. Target regions can exists where the mapped temperatures differ significantly from the source. – Manual- This option allows you to select one or more source bodies to make up the source mesh. The source body selections are made in the Material IDs field by entering the material IDs that correspond to the source bodies that you would like to use. Type material IDs and/or material ID ranges separated by commas to specify your selection. For example, type 1, 2, 5-10. The material IDs for the source bodies can be seen in Solution Information Object of the source analysis. In the example below, text is taken from a solver output, ***********Elements for Body 1 "coil" *********** ***********Elements for Body 2 "core" *********** ***********Elements for Body 3 "bar" ************

body 'coil' has material ID 1, body 'core' has material ID 2 and body 'bar' has material ID 3. 6. Change any of the columns in the Data View tab as needed: – Source Time - The time at which the data will be imported from the coarse analysis. – Analysis time - Choose the analysis time at which the load will be applied.

Note The Data View can automatically be populated with the source and analysis times using Source Time property in the Details view. Use All to import data at all times in the source analysis, or Range to import data for a range specified by a Minimum and a Maximum.

7. You can transform the source mesh used in the mapping process by using the Rigid Transformation properties. This option is useful if the source geometry was defined with respect to a coordinate system that is not aligned with the target geometry system.

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Analysis Types 8. You can modify the Mapper Settings to achieve the desired mapping accuracy. Mapping can be validated by using Mapping Validation objects. 9. Right-click the Imported Body Temperature object and click Import Load to import the load. When the load has been imported successfully, a contour plot of the temperatures will be displayed in the Geometry window. 10. You can define multiple rows in the Data View tab to import source data at multiple times and apply them at different analysis. If multiple rows are defined in the Data View, it is possible to preview imported load vectors/contour applied to a given row or analysis time in the Data View. Choose Active Row or Analysis Time using the By property under Graphics Controls in the details of the imported load and then specify the Active Row/Analysis Time to preview the data.

Note If the Analysis Time specified by the user does not match the list of analysis times in the Data View, the data is displayed at the analysis time closest to the specified time.

Note a. You can add a template for the linked thermal and structural systems by creating your own template. b. The transfer of temperatures is not allowed between a 2D analysis and 3D analysis or vice-versa.

Note When there is a shared model that includes a thermal-stress analysis and the structural system is duplicated using the Engineering Data, Geometry or Model cell context menu, the result is the Setup cell of the Thermal system linked to the Solution cell of the duplicated structural system. Temperature transfer to the duplicated structural system will require the data to be mapped and interpolated between the source and target meshes.

One-way Acoustic Coupling Analysis The Mechanical application allows you to apply velocities from a Structural Harmonic Response analysis as loads in an Acoustic analysis. The load transfer is applicable for the cases where the harmonic response and acoustic analyses are solved using different meshes. In this case, the velocity values are mapped and interpolated between the source and target meshes. An acoustic analysis is performed via ACT. For information on creating optimization extensions, see the Application Customization Toolkit Developer’s Guide and the Application Customization Toolkit Reference Guide. These documents are part of the ANSYS Customization Suite on the ANSYS Customer Portal. Workflow for performing a one-way acoustic coupling analysis. 1. From the toolbox, drag and drop a Harmonic Response template onto the project schematic. Perform all steps to set up a Harmonic Analysis. Specify mesh controls, boundary conditions, and solution settings as you normally would and solve the analysis.

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Special Analysis Topics 2. Drag and drop a Harmonic Response template onto the project schematic. Drag the Solution cell of the structural system onto the Setup cell of the acoustic system.

3. Double-click the acoustic system’s system Setup cell. In the Mechanical application, insert an Imported Velocity load into the acoustic system’s tree under an Imported Load folder. 4. Select appropriate geometry in the Details view of the imported velocity object using the Geometry or Named Selection scoping option. 5. The Source Bodies option in the Details view allows you to select the bodies, from the thermal analysis, that makeup the source mesh for mapping the data. You can choose one of the following options: • All- The source mesh in this case will comprise of all the bodies that were used in structural analysis. • Manual- This option allows you to select one or more source bodies to make up the source mesh. The source body selections are made in the Material IDs field by entering the material IDs that correspond to the source bodies that you would like to use. Type material IDs and/or material ID ranges separated by commas to specify your selection. For example, type 1, 2, 5–10. The material IDs for the source bodies can be seen in Solution Information Object of the source analysis. In the example below, text is taken from a solver output, ***********Elements for Body 1 "coil" *********** ***********Elements for Body 2 "core" *********** ***********Elements for Body 3 "bar" ************

body ‘coil’ has material ID 1, body ‘core’ has material ID 2 and body ‘bar’ has material ID 3. 6. Change any of the columns in the Data View tab as needed: • Source Frequency- Frequency at which the velocities will be imported from the structural analysis. • Analysis Frequency- Choose the analysis frequency at which the load will be applied.

Note The Data view can automatically be populated with the source and analysis frequencies using the Source Frequency property in the Details View. Use All to import data at all frequencies in the source analysis, or Range to import data for a range specified by a Minimum and Maximum. The default worksheet option requires users to manually input the Source Frequency and Analysis Frequency.

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Analysis Types 7. You can transform the source mesh used in the mapping process by using the Rigid Transformation properties. This option is useful if the source geometry was defined with respect to a coordinate system that is not aligned with the target geometry system. 8. You can modify the Mapper Settings to achieve the desired mapping accuracy. Mapping can be validated by using Mapping Validation objects. 9. Right-click the Imported Velocity object and click Import Load to import the load. When the load has been imported successfully, vectors plot (All), or contour plot (Total/X/Y/Z) of the real/imaginary components of velocities can be displayed in the Geometry window using the Component property in the details of imported load.

Note The range of data displayed in the graphics window can be controlled using the Legend controls options. See Imported Boundary Conditions for additional information.

10. If multiple rows are defined in the Data view, it is possible to preview imported load vectors/contour applied to a given row or analysis frequency in the Data view. Choose Active Row or Analysis Frequency using the By property under Graphics Controls in the details of the imported load and then specify the Active Row/Analysis Frequency to preview the data.

Note If the Analysis Frequency specified by the user does not match the list of analysis frequencies in the Data View, the data is displayed at the analysis frequency closest to the specified frequency.

Rotordynamics Analysis Rotordynamics is a specialized branch of applied mechanics that studies the behaviors of rotating structures. This rotating structure, or “rotor system “, is typically comprised of rotors, stators, and bearings. For a simple rotor system, the rotor component rotates about an axis that is stabilized by a bearing that is supported by a stator. This structure can be as simple as computer disk or as complicated as a jet engine. The Mechanical Rotordynamics Analysis helps to direct you when selecting properties such as rotor stiffness and geometry, bearing stiffness, damping, and stator properties for a rotor system based on a given rotating speed. For example, to effectively study a system’s vibratory characteristics, you can use a Campbell diagram. A Campbell diagram allows you to determine critical speeds (for different rotating modes), such as the rate at which the rotating structure experiences resonance (peak response) to avoid possible catastrophic failure. Or, a Rotordynamic Analysis can be used to determine safe operational ranges for a rotor system. In the Mechanical documentation, see the Rotordynamics Controls section for more information, and in the Mechanical APDL documentation, the Rotordynamic Analysis Guide. Refer to the following areas of the documentation for additional and associated information for Rotordynamics:

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Special Analysis Topics • Import Shaft Geometry • Bearings • Campbell Diagram Chart Results

Fracture Analysis Fracture analysis deals with the computation of fracture parameters that help you design within the limits of catastrophic failure of a structure. Fracture analysis assumes the presence of a crack in the structure. The fracture parameters computed are Stress Intensity Factors (SIFS), J-Integral (JINT) and Energy Release Rates. For more information about fracture parameters, modes, and calculation techniques, see Fracture Mechanics in the Structural Analysis Guide. Fracture analysis requires that you define a crack. Since fracture parameter calculation requires knowledge of the mesh characteristics around the crack, the mesh must be generated before solving for fracture parameters. Fracture parameter computation is only applicable to static structural analyses. For more information on Fracture Analysis, see the following topics: Cracks Solving a Fracture Analysis Fracture Results Limitations of Fracture Analysis Interface Delamination and Contact Debonding Additional topics include: Fracture Analysis Workflows Multi-Point Constraint (MPC) Contact for Fracture

Fracture Analysis Workflows This section describes the typical workflow for computing fracture parameters in the static structural analysis that contains cracks. The typical workflows are shown below:

Note For all workflows, the static structural analysis supports imported thermal loads from both steady-state thermal or transient thermal analysis by linking the set up cell of the static structural analysis to the upstream steady-state thermal or transient thermal analysis.

Known Crack Location The steps shown below describe setting up the fracture analysis when the location of crack is known. The crack location and its alignment are dictated by the coordinate system selected by the crack object. 1.

In ANSYS Workbench, insert a Static Structural analysis in the project schematic.

2.

Input geometry.

3.

Locate a coordinate system with a graphic pick point, coordinates, or topology. The coordinate system must be located on the surface.

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Analysis Types 4.

Align the axes of the coordinate system of the crack. The specified coordinate system's y-axis must be pointing in the direction normal to the crack surface. For cracks lying on curved surfaces, ensure that the coordinate system's x-axis is pointing normal to the surface of the body at the coordinate system location. See Creating a Coordinate System Based on a Surface Normal (p. 487) for details on how to orient such a coordinate system on a curved surface..

5.

Insert a Fracture folder in the Tree Outline.

6.

Insert a Crack object under the Fracture folder.

7.

Specify the crack object details.

8.

Generate the mesh by right-clicking the Fracture folder and selecting Generate All Crack Meshes.

9.

Apply loads and boundary conditions.

10. Apply any pressure on crack face if necessary. 11. Ensure the Fracture setting under Solver Controls in the Analysis Settings is turned on. 12. Solve. 13. Add the Fracture tool and Fracture Result. 14. Post process the Fracture Result. 15. Export to Excel or copy/paste from the chart if necessary.

Imported Crack Mesh This workflow describes using the Pre-Meshed crack object for the computation of fracture parameters in 2D and 3D analysis using imported crack mesh. 1.

In ANSYS Workbench, insert a Static Structural analysis in the project schematic.

2.

Input the mesh through FE Modeler. The imported mesh contains the crack mesh and its definition.

3.

Create a coordinate system with a Y axis perpendicular to the crack faces.

4.

Insert a Fracture folder in the Tree Outline.

5.

Insert a Pre-Meshed Crack object under the Fracture folder.

6.

Specify the crack object details.

7.

Associate the Pre-Meshed Crack object with the created coordinate system.

8.

Apply load and boundary conditions.

9.

Ensure the Fracture setting under Solver Controls in the Analysis Settings is turned on.

10. Solve. 11. Add the Fracture tool and Fracture Result. 12. Post process the Fracture Result.

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Special Analysis Topics 13. Export to Excel or copy/paste from the chart if necessary.

Note In 2D, you can draw the crack in the same model using DesignModeler and generate the crack mesh using the mesh connection feature. For a tutorial addressing this issue, see Fracture Analysis of a 2D Cracked Specimen using Pre-Meshed Crack (p. 1528).

Limitations of Fracture Analysis This section describes the limitations for the generation of crack mesh using Crack object. It also describes the limitations in the computation of fracture parameters using the Crack and Pre-Meshed crack objects. 1. Fracture analysis does not support adaptive mesh refinement. 2. The Crack object is only supported for 3D analysis. 3. The Crack object can only be scoped to one body. The base mesh on that body must be quadratic tetrahedron mesh. 4. The stiffness behavior of the scoped geometry selection of the Crack object must be flexible. 5. The scoped crack front nodal selection of the Pre-Meshed Crack object must exist in geometries with a flexible stiffness behavior definition. 6. Fracture parameter computations based on the VCCT technique are only supported for lower order crack mesh. Hence, VCCT based fracture parameter computations are only supported for Pre-Meshed Crack object. 7. Solution Restarts are not supported with the computation of fracture parameters. Solution Restarts can be used for solving an analysis of cracks without computing the fracture parameters by turning “Off” the “Fracture” setting under Solver Controls. 8. The Crack object only supports semi-elliptical surface cracks. 9. The crack top and bottom face nodes are not connected through any constraint equation. So the nodes of the top face can penetrate the bottom face or vice versa based on the applied loads and constraints. In these scenarios, you may need to create a constraint equation between crack faces during solution using the Commands object. 10. The graphical view of the crack may differ from the generated mesh. For more information, see the section on Cracks (p. 471). 11. Crack object is not supported for Cyclic Symmetry Region and Structural Linear Periodic Symmetry Region objects. 12. Interpolated displacements for the facets in a surface construction object may fail to demonstrate the proper deformation of a crack. For more information, see Surface Displays and Fracture (p. 1009).

Multi-Point Constraint (MPC) Contact for Fracture The internally generated crack mesh is created after an initial base mesh is generated. Since the crack mesh is defined based on the crack object, while the base mesh is created based on the geometry and mesh parameters, the two meshes may not perfectly match at the boundaries of the fracture affected Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Analysis Types zone. For more information on the fracture affected zone, see the Fracture Meshing section in the Meshing User's Guide. When a solution is performed on an analysis which contains an internally generated crack mesh, a contact region using Multi-Point Constraint (MPC) formulation is automatically created between the crack mesh and the base mesh at the boundaries of the fracture-affected zone. This contact is applicable to static structural analysis, steady-state thermal analysis, and transient thermal analysis. For more information about the MPC contact formulation, see Contact Formulation Theory. This contact is only created for a Crack object and is not applicable to the Pre-Meshed Crack object. The characteristics/settings of the MPC contact are shown below. For more information about the different contact settings, see Advanced Settings. • Bonded surface-to-surface contact is defined between the crack mesh and the base mesh at the boundary of the fracture-affected zone. The contact element CONTA174 is created on the faces of the crack mesh, and the target element TARGE170 is created on the faces of the base mesh. • The contact is asymmetric in nature. The contact can be made auto asymmetric by setting the use auto symmetric variable to 1 in the Variable Manager. • Nodal contact detection, normal from the contact surface, will be defined. • The initial gap and penetration are ignored. • For steady-state thermal and transient thermal analysis, the temperature degree of freedom is selected. For more information about contact settings, refer to the CONTA174 documentation in the Element Reference. For more information about the MPC constraint, see Multipoint Constraints and Assemblies in the Mechanical APDL Contact Technology Guide.

Composite Analysis Composite analysis can be performed inside Mechanical by importing the layered section information defined on a Mechanical model in an ACP system. The following information discusses the workflow for shell and solid modeling. • Shell Modeling Workflow (p. 364) • Solid Modeling Workflow (p. 366)

Shell Modeling Workflow Composite shells defined using ACP can be imported into Mechanical for analysis by using an Imported Layered Section object. To import composite shells from ACP into Mechanical follow the procedure below: 1. From the toolbox, drag and drop an ACP (Pre) system onto the project schematic. Perform all the steps to fully define the ACP (Pre) system. 2. Then drag and drop a supported* Mechanical system on the ACP (Pre) system. This will share the Engineering Data, Geometry and Model cells from ACP system to the Mechanical system.

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Special Analysis Topics

Note • A Section Data cell is inserted in the Mechanical system, which represents the imported section data. • An Imported Layered Section object is inserted in the Mechanical application when a transfer connection is created from the Setup of an ACP (Pre) system to a Section Data cell.

3. Perform all the steps to fully define the Mechanical system and perform analysis. 4. Review the results. Layered results can be viewed in Mechanical, see Surface Body Results for details. To utilize additional post processing capabilities within ACP, drag an ACP (Post) system onto the ACP (Pre) Model cell, then connect the Solution cell of the supported* Mechanical system onto the ACP (Post) Results cell.

Note • Multiple Mechanical systems can be linked to perform complex workflows exactly like standard analyses. Since only one layered section(s) definition can exist per Mechanical Model, for all the systems sharing the Model cell, Section Data cell is also shared.

• The following information is transferred from ACP Setup to Section Data cell: – Sections

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Analysis Types – Elements assigned to each section – Layers definition for each section – Material assignment for each layer Since the material assignment is transferred from ACP Setup to the Mechanical system, the engineering data cells of the ACP and Mechanical system(s) must be shared. The refresh of the ACP system fails if unshared Engineering Data cells are detected.

*Supported Mechanical system(s) • Static Structural • Transient Structural • Modal • Harmonic Response • Random Vibration • Response Spectrum • Explicit Dynamics • Linear Buckling

Solid Modeling Workflow A Composite solid defined using ACP can be imported into Mechanical for analysis by importing the mesh from upstream ACP system(s) and synthesizing the geometry from the imported meshes. To import a composite solid from ACP into Mechanical, follow the procedure below: 1. From the toolbox, drag and drop ACP (Pre) system onto the project schematic. Perform all the steps to fully define the ACP (Pre) system. 2. Then drag and drop a supported* Mechanical system onto the project schematic and create a transfer link from ACP (Pre) Setup cell to the Mechanical System model. This connection enables the transfer of mesh, geometry and engineering data from ACP (Pre) Setup cell to Mechanical Model cell.

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Special Analysis Topics Figure 19: ACP - Mechanical Connection

Note • Since the geometry and engineering data is provided by the upstream ACP system, they are removed from the downstream Mechanical system. • Meshes can be imported into Mechanical from multiple ACP systems. Mechanical does not allow overlap of node/element number from multiple ACP systems; therefore, the import fails if the meshes from different ACP systems have overlap in node/element numbers.

3. Double click/edit the downstream Model cell. In the Mechanical application, an Imported Layered Section object is already inserted. 4. Perform all the steps to fully define the Mechanical system and perform analysis.

Note • Since the mesh is imported from an upstream Mechanical system, any operations that affect the mesh state are blocked inside of Mechanical. • It is recommended that you do not affect the mesh inside Mechanical; however, the Clear Generated Data option is available on the mesh folder inside Mechanical and cleans the imported mesh. The Generate Mesh/Update operation resumes the imported mesh previously cleaned/modified. • Since the material is assigned to elements/bodies through upstream ACP system, the Material Assignment field is read only and says, “Composite Material”. • If the Setup cell of the upstream ACP system(s) is modified, then the refresh of the downstream Model cell re-imports the meshes and re-synthesizes the geometry. This has the following effects: – Any properties set on the bodies imported from ACP system are reset to the defaults. – Any scoping to geometry (bodies/faces/edges/vertices) is lost and any loads/boundary conditions scoping to geometry have to be re-scoped. • Any criterion based named selections defined in the downstream Mechanical system are updated on refresh after any modification in upstream ACP system.

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Analysis Types – Since criterion based named selections are automatically updated, where as any direct scoping is lost, user should create criterion based named selections and then scope any loads/boundary conditions to these named selections. This will result in persistence of scoping during modify/refresh operations.

5. Review the results. Layered results can be viewed in Mechanical, see Surface Body Results for details. To utilize additional postprocessing capabilities within ACP, drag an ACP (Post) system onto the ACP (Pre) Model cell, then connect the Solution cell of the supported* Mechanical system onto the ACP (Post) Results cell.

Mixing of composite (layered) solids and non-layered shells/solids Non-layered shells/solids can also be imported into Mechanical along with layered solids to perform mixed analysis, where some bodies have layer information and others do not. To perform mixed analysis inside of Mechanical: 1. First drag and drop an ACP (Pre) system onto the project schematic. 2. Then drag and drop a supported* Mechanical system onto the project schematic and create a link from ACP (Pre) Setup cell to Mechanical System Model cell. 3. Then drag and drop Mechanical Model system onto the project schematic and create a transfer link from Model cell of upstream system to Model cell of downstream system.

Note • Meshes from upstream to downstream Mechanical Model are renumbered automatically to avoid any overlap with the meshes imported from ACP system(s).

4. Double-click/edit the downstream Model cell. In the Mechanical application, an Imported Layered Section is already inserted. 5. Perform all the steps to fully define the Mechanical system and perform analysis.

Note • The following information is transferred from upstream to downstream Mechanical Model:

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Special Analysis Topics – Geometry (Parts/Bodies) and material assigned to bodies. – Mesh – Named selections scoped to face(s) • Since the material assignment is transferred from upstream to downstream Mechanical system, the Material Assignment field is read only and displays the material assigned to the body. • If the model cell of the upstream Model system or the Setup cell of the ACP system is modified, then the refresh of the downstream Model cell re-imports the meshes and resynthesizes the geometry. Any properties set on the bodies imported from the Mechanical model are retained.

6. Review the results. Layered results can be viewed in Mechanical, see Surface Body Results for details. To utilize additional postprocessing capabilities within ACP, drag an ACP (Post) system onto the ACP (Pre) Model cell, then connect the Solution cell of the supported* Mechanical system onto the ACP (Post) Results cell. *Supported Mechanical system(s) • Static Structural • Transient Structural • Steady-State Thermal • Transient Thermal • Modal • Harmonic Response • Random Vibration • Response Spectrum • Linear Buckling

Note Although both Structural and Thermal layer modeling is available, the particular degrees of freedom results on correspondent layers could behave differently in structural and thermal environments, see the Mechanical APDL Element Reference for correspondent elements, including: SOLID185 Layered Structural Solid Assumptions and Restrictions and SOLID278 Layered Thermal Solid Assumptions and Restrictions.

Limitations If the Engineering Data Cell of the intended downstream Mechanical System is modified (by creating/modifying an existing material in Engineering Data cell of the Mechanical System), a Data Transfer

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Analysis Types connection from Upstream ACP (Pre) Setup/Mechanical Model to downstream Mechanical system cannot be created.

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Specifying Geometry in the Mechanical Application The following topics are included in this section: Geometry Basics Solid Bodies Surface Bodies Line Bodies Mesh-Based Geometry Assembling Mechanical Models Rigid Bodies 2D Analyses Symmetry Named Selections Mesh Numbering Path (Construction Geometry) Surface (Construction Geometry) Remote Point Point Mass Thermal Point Mass Cracks Interface Delamination and Contact Debonding Gaskets

Geometry Basics While there is no limit to the number of parts in an assembly that can be treated, large assemblies may require unusually high computer time and resources to compute a solution. Contact boundaries can be automatically formed where parts meet. The application has the ability to transfer structural loads and heat flows across the contact boundaries and to "connect" the various parts. Parts are a grouping or a collection of bodies. Parts can include multiple bodies and are referred to as multibody parts. The mesh for multibody parts created in DesignModeler will share nodes where the bodies touch one another, that is, they will have common nodes at the interfaces. This is the primary reason for using multibody parts. Parts may consist of: • One or more solid bodies. • One or more surface bodies. • One or more line bodies. • Combinations of line and surface bodies.

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Specifying Geometry All other combinations are not practically supported.

Note Body objects in the tree that represent a multibody part do not report centroids or moments of inertia in their respective Details view. The following topics are addressed in this section: Multibody Behavior Working with Parts Associativity Integration Schemes Color Coding of Parts Working with Bodies Hide or Suppress Bodies Hide or Show Faces Assumptions and Restrictions for Assemblies, Parts, and Bodies

Multibody Behavior Associativity that you apply to geometry attached from DesignModeler is maintained in the Mechanical and Meshing applications when updating the geometry despite any part groupings that you may subsequently change in DesignModeler. See Associativity (p. 372) for further information. When transferring multibody parts from DesignModeler to the Meshing application, the multibody part has the body group (part) and the prototypes (bodies) beneath it. When the part consists of just a single body the body group is hidden. If the part has ever been imported as a multibody part you will always see the body group for that component, regardless of the number of bodies present in any subsequent update.

Working with Parts There are several useful and important manipulations that can be performed with parts in an assembly. • Each part may be assigned a different material. • Parts can be hidden for easier visibility. • Parts can be suppressed, which effectively eliminates the parts from treatment. • The contact detection tolerance and the contact type between parts can be controlled. • When a model contains a Coordinate Systems object, by default, the part and the associated bodies use the Global Coordinate System to align the elements. If desired, you can apply a local coordinate system to the part or body. When a local coordinate system is assigned to a Part, by default, the bodies also assume this coordinate system but you may modify the system on the bodies individually as desired.

Associativity Associativity that you apply to geometry originating from DesignModeler is maintained in the Mechanical and Meshing applications when the geometry is updated despite any part groupings that you may

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Geometry Basics subsequently change in DesignModeler. Types of associativity that you can apply include contact regions, mesh connections, loads, and supports. For example, consider the following scenario: 1. A model is created in DesignModeler and is comprised of six independent parts with one body per part. 2. The model is attached to Mechanical where loads and supports are applied to selected geometry. 3. In DesignModeler, the model is re-grouped into two multibody parts with each part including three bodies. 4. The geometry is updated in Mechanical. The loads and supports remain applied to the same selected geometry.

Note This feature does not hold true for instanced parts in DesignModeler. The associativity is maintained only with geometry attached from DesignModeler and Mechanical systems created in release 13.0 or later. To ensure that the data necessary for retaining associativity is present in legacy dsdb/wbpj databases, you should perform the following: 1. Open the Mechanical session and open the DesignModeler session. This will ensure that both the Mechanical and DesignModeler files are migrated to the current version of the software. 2. Update the geometry model without making any changes to the model. This will ensure that the new data necessary for associativity is transferred from the migrated DesignModeler file into the migrated Mechanical file. 3. You can now modify and update the geometry as necessary.

Maintaining Associativity with Geometry Updates in FE Modeler When updating a model from FE Modeler in Mechanical, all geometry scoping on objects (such as loads, results, etc.) is lost. For this reason, it is recommended that you either use imported named selections or criteria-based named selections for scoping of objects, since these are automatically updated when the model update is complete.

Integration Schemes Parts can be assigned Full or Reduced integration schemes. The full method is used mainly for purely linear analyses, or when the model has only one layer of elements in each direction. This method does not cause hourglass mode, but can cause volumetric locking in nearly incompressible cases. The reduced method helps to prevent volumetric mesh locking in nearly incompressible cases. However, hourglass mode might propagate in the model if there are not at least two layers of elements in each direction.

Color Coding of Parts You can visually identify parts based on a property of that part. For example, if an assembly is made of parts of different materials, you can color the parts based on the material; that is, all structural steel parts have the same color, all aluminum parts have the same color and so on. Select a color via the Display Style field of the Details view when the Geometry branch in the feature Tree is selected. You can specify colors based on: Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Specifying Geometry • Body Color (default): Assigns different colors to the bodies within a part. • Part Color: Assigns different colors to different parts. • Material: The part colors are based on the material assignment. For example in a model with five parts where three parts use structural steel and two parts use aluminum, you will see the three structural steel parts in one color and the two aluminum parts in another color. The legend will indicate the color used along with the name of the material. • Nonlinear Material Effects: Indicates if a part includes nonlinear material effects during analysis. If you chose to exclude nonlinear material effects for some parts of a model, then the legend will indicate Linear for these parts and the parts will be colored accordingly. • Stiffness Behavior: Identifies a part as Flexible, Rigid, or Gasket during analysis.

Note A maximum of 15 distinct materials can be shown in the legend. If a model has more then 15 materials, coloring by material will not have any effect unless enough parts are hidden or suppressed. You can reset the colors back to the default color scheme by right clicking on the Geometry object in the tree and selecting Reset Body Colors. Example 2: Color by Parts

Working with Bodies There are several useful and important manipulations that can be performed with bodies in a part. • Bodies grouped into a part result in connected geometry and shared nodes in a mesh. • Each body may be assigned a different material. • Bodies can be hidden for easier visibility.

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Geometry Basics • Bodies in a part group can be individually suppressed, which effectively eliminates these bodies from treatment. A suppressed body is not included in the statistics of the owning part or in the overall statistics of the model. • Bodies can be assigned Full or Reduced integration schemes, as described above for parts. • When bodies in part groups touch they will share nodes where they touch. This will connect the bodies. If a body in a part group does not touch another body in that part group, it will not share any nodes. It will be free standing. Automatic contact detection is not performed between bodies in a part group. Automatic contact detection is performed only between part groups. • Bodies that are not in a part group can be declared as rigid bodies. • When a model contains a Coordinate Systems object, by default, bodies use the Global Coordinate System. If desired, you can apply a local coordinate system.

Hide or Suppress Bodies For a quick way to hide bodies (that is, turn body viewing off ) or suppress bodies (that is, turn body viewing off and remove the bodies from further treatment in the analysis), select the bodies in the tree or in the Geometry window (choose the Body select mode, either from the toolbar or by a right-click in the Geometry window). Then right-click and choose Hide Body or Suppress Body from the context menu. Choose Show Body, Show All Bodies, Unsuppress Body, or Unsuppress All Bodies to reverse the states. The following options are also available: • Hide All Other Bodies, allows you to show only selected bodies. • Suppress All Other Bodies, allows you to unsuppress only selected bodies.

Note • If another model level object, such as a Remote Point, Joint, or Contact Region, is scoped to a Body that becomes Suppressed, that object also becomes suppressed until it is re-scoped or the body is Unsuppressed. • Results from hidden bodies are used in the formulation of the maximum and minimum values in the contour legend and in the Details View. • Results from suppressed bodies are suppressed and are not used in the formulation of maximum and minimum values.

Hide or Show Faces You can hide selected faces on a model such that you are able to see inside the model. This feature is especially useful for bodies with interior cavities, such as engine blocks. To use the feature, first select faces on the model that you want to hide, then right-click anywhere in the Geometry window and choose Hide Face(s) in the context menu. This menu choice is only available if you have already selected faces.

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Specifying Geometry Choose Show Hidden Face(s) from the context menu to restore the visibility of faces previously hidden using Hide Face(s). The Show Hidden Face(s) menu choice is only available if there are hidden faces from choosing Hide Face(s). It cannot be used to restore the visibility of faces previously hidden by setting Visible to No in the Details view of a Named Selection object.

Note The selected faces will appear hidden only when you view the geometry. The feature is not applicable to mesh displays or result displays.

Assumptions and Restrictions for Assemblies, Parts, and Bodies Thermal and shape analysis is not supported for surface bodies or line bodies. In order for multiple bodies inside a part to be properly connected by sharing a node in their mesh the bodies must share a face or edge. If they do not share a face or an edge the bodies will not be connected for the analysis which could lead to rigid body motion. Automatic contact detection will detect contact between bodies within a multibody part.

Solid Bodies You can process and solve solid models, including individual parts and assemblies. An arbitrary level of complexity is supported, given sufficient computer time and resources.

Surface Bodies You can import surface bodies from an array of sources (see Geometry Preferences). Surface bodies are often generated by applying mid-surface extraction to a pre-existing solid. The operation abstracts away the thickness from the solid and converts it into a separate modeling input of the generated surface. Surface body models may be arranged into parts. Within a part there may be one or more surface bodies; these may even share the part with line bodies. Parts that feature surface bodies may be connected with the help of spot welds and contacts. The following topics are addressed in this section. Assemblies of Surface Bodies Thickness Mode Importing Surface Body Models Importing Surface Body Thickness Surface Body Shell Offsets Specifying Surface Body Thickness Specifying Surface Body Layered Sections Faces With Multiple Thicknesses and Layers Specified

Assemblies of Surface Bodies While preparing an assembly of surface bodies for solution you may find the need to understand and modify the connectivity of the bodies involved. Mechanical offers tools to help you accomplish these tasks. For example, you may:

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Surface Bodies • Confirm whether two surface bodies are topologically connected. This may be especially useful for surface bodies obtained from a mid-surface operation on solids and created artificial gaps in their proximity. • Confirm the connectivity of individual elements in the mesh of the surface bodies. • Mend missing connections between surface bodies by joining their meshes with shared nodes. To confirm the connectivity of surface bodies it is useful to review the connectivity of their edges using a number of features in both Mechanical and DesignModeler. Edges can be classified depending on the number of faces they topologically connect. For example, the boundary edge of a surface body connects to a single face and is classified as a "single edge”, whereas an interior edge connecting two faces of the surface body will be classified as a "double edge". Single and double edges can be distinguished visually using the Edge Graphics Options (p. 71). As an alternative, you can create a Named Selection that groups all edges of a given topological connectivity by using the Face Connections criterion. The Edge Graphics Options toolbar can also be used to review the connectivity of not only the geometry, but also the mesh elements. The same principles applied to the connectivity of a surface body edge apply to element edges. Mechanical provides Mesh Connections to mend surface body assemblies at locations that are disjointed. With this feature, the meshes of surface bodies that may reside in different parts can be connected by joining their underlying elements via shared nodes. The Mesh Connection does not alter the geometry although the effect can be conveniently previewed and toggled using the Edge Graphics Options toolbar.

Thickness Mode You can determine the source that controls the thickness of a surface body using the Thickness Mode indication combined with the Thickness field, both located in the Details view of a surface Body object. Upon attaching a surface body, the Thickness Mode reads either Auto or Manual. • In Auto Mode the value of thickness for a given surface body is controlled by the CAD source. Future CAD updates will synchronize its thickness value with the value in the CAD system. • In Manual mode the thickness for the surface body is controlled by the Mechanical application, so future updates from the CAD system will leave this value undisturbed. • A Thickness Mode will be Automatic until the Thickness is changed to some non-zero value. Once in Manual mode, it can be made Automatic once again by changing the Thickness value back to zero. A subsequent CAD update will conveniently synchronize the thickness with the value in the CAD system. Thicknesses for all surface bodies are represented in a dedicated column on the Worksheet that is displayed when you highlight the Geometry object.

Importing Surface Body Models To import a surface body model (called a sheet body in NX), open the model in the CAD system and import the geometry as usual. If your model mixes solid bodies and surface bodies, you should select which type of entity you want to import via the Geometry preferences in the Workbench Properties

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Specifying Geometry of the Geometry cell in the Project Schematic. Once in the Mechanical application, you can adjust the Geometry preferences in the Details view, where they take effect upon updating.

Note If you want to retain a preference selection in the Workbench Properties, you must first save before exiting the ANSYS Workbench.

Importing Surface Body Thickness When thickness is defined on the entire surface body Surface body thickness will be imported from CAD (including DesignModeler) if, and only if, the existing surface body thickness value in the Mechanical application is set to 0 (zero). This is true on initial attach and if you set the surface body thickness value to zero prior to an update. This allows you the flexibility of updating surface body thickness values from CAD or not.

Surface Body Shell Offsets Surface bodies have a normal direction, identified by a green coloring when the surface body face is selected. Shell elements have a “top” surface (farthest in the positive normal direction) and a “bottom” (farthest in the negative normal direction).

By default, the shell section midsurface is aligned with the surface body, but you can use the Offset Type drop down menu located in the Details view of a Surface Body object or an object scoped to a surface body to offset the shell section midsurface from the surface body: • Top - the top of the shell section is aligned with the surface body.

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Surface Bodies

• Middle (Membrane) (default) - the middle of the shell section is aligned with the surface body.

• Bottom - the bottom of the shell section is aligned with the surface body.

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Specifying Geometry

• User Defined - the user defines the amount of offset (Membrane Offset), measured in the positive normal direction from the middle of the shell section to the surface body (may be positive or negative value).

Specifying Surface Body Thickness The thickness of surface bodies can be prescribed in several ways: 1. A uniform thickness over the entire body which can be defined inside Mechanical or imported from a CAD system. Thicknesses imported from CAD can be overridden by the Thickness Mode 2. A constant or spatially varying thickness applied to a selection of surfaces or bodies. 3. Thickness values imported from an upstream system. 4. Layer information can be specified using a Layered Section, or imported through an Imported Layered Section. See Faces With Multiple Thicknesses and Layers Specified (p. 386) for information on how Mechanical resolves conflicts when multiple thickness specifications are applied to the same geometry. 380

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Surface Bodies To specify the thickness of an entire surface body: Highlight the Surface Body object and, in the Details view, enter a value in the Thickness field. A value greater than 0 must be present in this field. To specify the thickness of selected faces on a surface body: 1. Highlight the Geometry folder in the tree and insert a Thickness object from the Geometry toolbar or choose Insert> Thickness (right-click and choose from context menu).

Note The Thickness object overwrites any element that is scoped to the selected surfaces that has thickness greater than 0 defined in the Details view of the Surface Body object (See above).

2. Apply scoping to selected faces on surface bodies. 3. Set the desired shell offset. 4. Define the thickness as a constant (default), with a table, or with a function: a. To define the thickness as a constant, enter the value in the Thickness field in the Details view. b. To define the thickness with a table: i.

Click the Thickness field in the Details view, then click Tabular from the flyout menu.

ii. Set the Independent Variable in the Details view to X, Y, or Z. iii. Choose a Coordinate System. The Global Coordinate System (Cartesian) is the default. iv. Enter data in the Tabular Data window. The Graph window displays the variation of the thickness. c. To define the thickness with a function: i.

Click the Thickness field in the Details view, then click Function from the flyout menu.

ii. Enter the function in the Thickness field. (Example: 45+10*x/591) iii. Adjust properties in the Graph Controls category as needed: • Number of Segments - The function is graphed with a default value of 200 line segments. You can change this value to better visualize the function. • Range Minimum - The minimum range of the graph. • Range Maximum - The maximum range of the graph.

Note • Surface body thicknesses must be greater than zero. Failures will be detected by the solver.

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Specifying Geometry • When importing surfaces bodies from DesignModeler, the associated thickness is automatically included with the import. See Importing Surface Body Thickness (p. 378) for details. • Face based thickness specification is not used for the following items. Instead the body based thickness will be used: – Assembly properties: volume, mass, centroid, and moments of inertia. This is for display in the Details view only. The correct properties based on any variable thickness are correctly calculated in the solver and can be verified through miscellaneous record results for Mechanical APDL based solutions.

Note Assembly properties are displayed as N/A (Not Applicable) if Thickness objects (Thickness, Layered Thickness, Imported Layered Thickness) are present under the Geometry object. Also, that if any Parameters are present they are set to zero. This applies to parameter value you Workbench as well - they will have values of zero.

– Meshing: auto-detection based on surface body thickness, automatic pinch controls, surface body thickness used as mesh merging tolerance. – Solution: Heuristics used in beam properties for spot welds. • Face based thickness is not supported for rigid bodies. • Variable thickness is displayed only for mesh and result displays. Location probes, Path scoped results and Surface scoped results do not display nor account for variable thickness. They assume constant thickness. • If multiple Thickness objects are applied to the same face, only those properties related to the last defined object will be sent to the solver, regardless of whether the object was defined in DesignModeler or in Mechanical. See Faces With Multiple Thicknesses and Layers Specified (p. 386) for details.

You can import thicknesses from an upstream system. Basic setup steps are given below. You can find more information on mapping data in the Mechanical application in the appendix (Appendix C (p. 1595)).

Note Thickness import is supported for 3D shell bodies or planar 2D bodies using Plane Stress. The MAPDL Solver for 3D shell bodies will use the nodal thicknesses directly via the SECFUNCTION command. For the Explicit Solver or MAPDL solver for 2D bodies, the element's nodal thicknesses are converted to an average element thickness. To import thicknesses from an upstream system: 1. In the project schematic, create a link between the Solution cell of a system and the Model cell of an upstream system.

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Surface Bodies 2. Attach geometry to the analysis system, and then double-click Model to open the Mechanical window. An Imported Thickness folder is added under the Geometry folder and an imported thickness is added to the Imported Thickness folder, by default. 3. Select the appropriate options in the Details view. 4. Select Imported Thickness and select Import Thickness from the context menu.

Specifying Surface Body Layered Sections Layers applied to a surface body can be prescribed in several ways: • A defined Layered Section object can be scoped to a selection of surfaces on the geometry. • An Imported Layered Section can provide layer information for the elements within a surface body.

Note Layered Section objects can only be used in the following analysis types: • Explicit Dynamics • Harmonic Response • Linear Buckling • Modal • Random Vibration • Response Spectrum • Static Structural • Transient Structural

The following sections describe the use of the Layered Section object. Defining and Applying a Layered Section Viewing Individual Layers Layered Section Properties Notes on Layered Section Behavior

Defining and Applying a Layered Section 1. Highlight the Geometry object in the tree and insert a Layered Section object from the Geometry toolbar or choose Insert > Layered Section (right-click and choose from context menu). 2. Select the Scoping Method that you will use: • Geometry Selection - Click in the Geometry field that appears, to enable you to pick surface bodies or individual faces from the model and select Apply. • Named Selection - Click on the Named Selection drop down that appears and select one of the available named selections. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Specifying Geometry 3. Choose a Coordinate System. You may choose any user-defined Cartesian or Cylindrical coordinate system. The Body Coordinate System option specifies that the coordinate system selected for each body will be used. There is no default. 4. Set the desired Offset Type. Offset Type is not supported in Explicit Dynamics analyses. 5. Click on the arrow to the right of Worksheet in the Layers field then select Worksheet to enter the layer information for this Layered Section. The Layered Section worksheet can also be activated by the Worksheet toolbar button. The worksheet displays a header row, and two inactive rows labeled +Z and -Z to indicate the order in which the materials are layered. Layer one will always be the layer at the bottom of the stack (closest to -Z). When you insert a layer, all of the layers above it will renumber. To add the first layer, right click anywhere in the Layered Section Worksheet and select Add Layer. Once the layer is added: • Click in the Material column of the row and select the material for that layer from the drop-down list. • Click in the Thickness column and define the thickness of that layer. Individual layers may have zero thickness, but the total layered-section thickness must be nonzero. • Click in the Angle column and define the angle of the material properties. The angle is measured in the element X-Y plane with respect to the element X axis. This value can be entered as degrees or radians, depending on how units are specified. To add another layer, do one of the following: • With no layers selected, you can right click the header row, +Z row, or -Z row to display a context menu. Select Add Layer to Top to add a layer row at the top (+Z) of the worksheet. Select Add Layer to Bottom to add a layer row to the bottom of the worksheet (-Z). • With one or more layers selected, you can right click any selected layer to display a context menu. Select Insert Layer Above (which inserts a layer row above the selected row in the +Z direction) or Insert Layer Below (which inserts a layer row below the selected row in the -Z direction). To delete a layer, select one or more rows, right click on any selected row, and select Delete Layer. 6. Select the Nonlinear Effects and Thermal Strain Effects settings in the Material category of the Details view. The reference temperature specified for the body on which a layered section is defined is used as the reference temperature for the layers. Nonlinear Effects and Thermal Strain Effects are not supported in Explicit Dynamics analyses.

Viewing Individual Layers In the Graphics Properties section of the Details panel, the Layer To Display field allows the visualization of the thickness/offset/layer sequence of the layers composing a Layered Section object. To view a particular layer, click on the field and enter the layer number. You can use the up and down buttons or enter a layer number directly. If you enter a number larger than the maximum number of layers in that layered section, the value will be set to the maximum number of layers in that layered section. If layer zero is selected, all the layers will be drawn (without the delineation between layers) as a compact entity, shown the same as when the Mesh node is selected in the tree. All other geometry not scoped to the current Layered Section object is shown with thickness zero.

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Surface Bodies Individual layers will be visible only when Show Mesh is enabled (if the model has been meshed previously), and only on Layered Section objects. If Show Mesh is not enabled, just the geometry and the scoping will be shown on the model. When a layer is selected to display, the layer with its defined thickness, offset, and sequence will be displayed in the graphics window. Due to the limitations described for the Show Mesh option, it is recommended that the user switch back and forth if needed to Wireframe/Shaded Exterior View mode to properly see annotations.

Note When viewing Imported Layered Sections, the thickness that you see is not relative to the geometry like it is with a Layered Section object.

Layered Section Properties The following Properties are displayed in Details panel for Layered Sections: • Total Thickness - Total thickness of the section, including all of the layers defined for the section. Used when displaying the mesh. • Total Mass - Total mass of all of the layers in the section. The density of the material for each layer is calculated at a reference temperature of 22° C.

Notes on Layered Section Behavior Note • If multiple thickness objects (including Layered Section objects) are applied to the same face, only those properties related to the last defined object will be sent to the solver, regardless of whether the object was defined in DesignModeler or in Mechanical. See Faces With Multiple Thicknesses and Layers Specified (p. 386) for details. • If adjacent elements within the same part have different thickness values, the elements will appear to be ramped. • Layered Sections cannot be scoped to rigid bodies. • Layered Sections do not affect the following items: – Assembly properties: volume, mass, centroid, and moments of inertia. This is for display in the Details view only. The correct properties based on any variable thickness are correctly calculated in the solver and can be verified through miscellaneous record results for Mechanical APDL based solutions. – Meshing: auto-detection based on surface body thickness, automatic pinch controls, surface body thickness used as mesh merging tolerance. – Solution: Heuristics used in beam properties for spot welds. • A Thermal Condition applied to a Layered Section is only valid if applied to both shell faces (Shell Face is set to Both, not to Top or Bottom).

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Specifying Geometry • Layered Sections are not valid with cyclic symmetry. • The following material properties are supported by Layered Sections in an Explicit Dynamics analysis: – Isotropic Elasticity, Orthotropic Elasticity – Johnson Cook Strength, Zerilli Armstrong Strength, Steinberg Guinan Strength, Cowper Symonds Strength – Orthotropic Stress Limits, Orthotropic Strain Limits, Tsai-Wu Constants – Plastic Strain, Principal Stress, Stochastic Failure, • For orthotropic materials in Explicit Dynamics, the Z material direction is always defined in the shell normal direction. The X material direction in the plane of each element is determined by the x-axis of the coordinate system associated with the Layered Section. If the x-axis of this coordinate system does not lie in the element plane, then the x-axis is projected onto the shell in the coordinate system z-axis direction. If the z-axis is normal to the element plane, then the projection is done in the coordinate system y-axis. For cylindrical systems, it is the y-axis that is projected onto the element plane to find the Y material direction.

Faces With Multiple Thicknesses and Layers Specified Thickness and Layered Section objects may be scoped to more than one face of a surface body. As a result, a face may have more than one thickness definition. The order of precedence used to determine the thickness that will be used in the analysis is as follows: 1. Imported Layered Section objects 2. Imported Thickness objects 3. Layered Section objects 4. Thickness objects 5. Thickness as a property of a body/part For multiple objects of the same type, the object lower in the tree (more recently created) will be used in the analysis. This thickness may not be the desired thickness to be used in the analysis. In a large model, you may want to fix this problem prior to solving the model. You can search for faces with multiple thicknesses by selecting Search Faces with Multiple Thicknesses from the context menu of any of the following: the Geometry folder, a Body object (individual or group of objects), a Thickness object or a Layered Section object. For each face found with multiple thicknesses, a warning message similar to the one shown below will be displayed in the message box. This face has more than one thickness defined. You may graphically select the face via RMB on this warning in the Messages window.

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Line Bodies To find the face and its corresponding thickness objects for a particular message, highlight that message in the message pane, right-click on the message and choose Go To Face With Multiple Thicknesses from the context menu. The face associated with this message is highlighted in the Geometry window and the corresponding thickness objects are highlighted in the tree. If there is no face with multiple definitions, the following information will be displayed in the message box. No faces with multiple thicknesses have been found. A related Go To option is also available. If you highlight one or more faces with thickness definition of a surface body, then right-click in the Geometry window and choose Go To> Thicknesses for Selected Faces, the corresponding thickness objects will be highlighted in the tree.

Note You cannot search for Imported Layered Sections that overlap with other thickness objects. However a warning will be generated during the solution if this situation might exist.

Line Bodies A line body consists entirely of edges and does not have a surface area or volume. Although multiple CAD sources can provide line bodies to ANSYS Workbench, only DesignModeler and ANSYS SpaceClaim Direct Modeler provide the additional cross section data needed to use line bodies in an analysis. For those CAD sources that cannot provide the cross section data, you need to import them into DesignModeler or ANSYS SpaceClaim Direct Modeler, define the cross sections, and then send the geometry to the Mechanical application in ANSYS Workbench. Once imported, a line body is represented by a Line Body object in the tree, where the Details view includes the associated cross section information of the line body that was defined in DesignModeler or supported CAD system. Depending on your application, you can further define the line body as either a beam or a pipe. Here are some guidelines: • Beam is usually a suitable option when analyzing thin to moderately thick beam structures. A variety of cross-sections can be associated with beams. • Pipes are more suitable for analyzing initially circular cross-sections and thin to moderately thick pipe walls. Users can apply special loads on pipes such as Pipe Pressure and Pipe Temperature. Curved pipe zones or high deformation zones in pipes can be further modeled using the Pipe Idealization object. To define your line body, highlight the Line Body object and set the following in the Details view: 1. Offset Mode: to Refresh on Update (default) to enable the values in the Details view to update when the CAD system updates, or to Manual, to enable the Details view values to override the CAD system updates. 2. Model Type: to Beam or Pipe. 3. Offset Type: to Centroid, Shear Center, Origin, or User Defined, where Offset X and Offset Y are available. The following read-only information is used in the definition of both beam and pipe: • Cross Section Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Specifying Geometry • Cross Section Area • Cross Section IYY • Cross Section IZZ

Note • Beams can also be used as connections within a model. See Beam Connections (p. 614) for further information on this application. • Pipes are only realized in structural analyses. All line bodies defined in other analysis types are always realized as beams. This extends to linked analyses as well. For example, in a thermalstructural linked analysis where line bodies are defined as pipes, the thermal component of the analysis will only realize the line bodies as beams.

Viewing Line Body Cross Sections By default, line bodies are displayed simply as lines in the Geometry window, with no graphical indication of cross sections. If cross sections are defined in line bodies and you choose View> Cross Section Solids (Geometry), you enable a feature where line bodies are displayed as solids (3D), allowing you to visually inspect the cross sections. This visualization can be useful in determining the correct orientation of the line bodies. For circular and circular tube cross sections, the number of divisions used for rendering the line bodies as solids has an adjustable range from 6 to 360 with a default of 16. You can make this adjustment by choosing Tools> Options, and under Graphics, entering the number in the Number of Circular Cross Section Divisions field. The Cross Section Solids (Geometry) feature has the following characteristics: • By default, this feature is disabled. However, the setting persists as a session preference. • Only geometry displays are applicable. The feature is not available for mesh displays. • When the feature is enabled, both normal lines and solid representations are drawn. • The solid representation of the geometry cannot be selected nor meshed, and has no effect on quantitative results. • The feature supports section planes and works with all line body cross sections (primitive and user defined). • User integrated sections (direct entry of properties) will have no display. • The feature is not available for use with viewports.

Mesh-Based Geometry For solid and shell finite element mesh files generated in the Mechanical APDL common database (.cdb) format, you can import these files directly into Mechanical using the Workbench External Model system. This feature automatically synthesizes geometry from the specified mesh for use in Mechanical. The resulting geometry is the culmination of the use of the implicit (based angle tolerance) and explicit (based on node-based components in the .cdb file) methods that work in combination to synthesize geometry and create surfaces that enclose the mesh volume.

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Mesh-Based Geometry This feature supports all Mechanical analysis types. For the specific instructions to import a finite element mesh file using this tool, see the Creating and Configuring an External Model System section of the Workbench Help.

External Model Properties in Workbench The External Model component allows you to modify certain properties prior to import; including: unit systems, the number copies of the source mesh to transform, and Rigid Transformation coordinates based on source locations.

Model Properties in Workbench There are CDB Import Options available in the properties for the Model cell in the Workbench Project page. Properly defining these properties is important for you to accurately generate the desired geometries in Mechanical. As shown, CDB Import Options include: • Tolerance Angle: this value determines if adjacent elements are of the same face during the geometry creation process. The geometry creation process identifies groups of element facets on the exterior of the mesh. These generated facets create geometric faces in Mechanical. Then skin detection algorithm scans the exterior element facets and groups them based on a tolerance angle. For example, two adjacent element facets are grouped into the same face if the angle between their normals is less than or equal to the given tolerance angle. Therefore, an angle tolerance of 180o creates only a single face for the whole body while a tolerance of 1o creates an amount of geometric faces which approaches the number of element faces if any curvature is present. Calculations to synthesize geometries using tolerance angles use the implicit method. Processing nodal components on the same topology will override this method. See the illustrations below for examples of this behavior. The default Tolerance Angle is 45 degrees. This is the recommended setting. • Process Nodal Components: this option overrides Tolerance Angle during the geometry creation process if the .cdb file contains node-based components. And like Tolerance Angle, when node-based components span large portions of a model, clarity inaccuracies display in the graphical display of Mechanical. • Nodal Component Key: if the .cdb files includes nodal components, you can specify them using this property to further facilitate accurate geometries in Mechanical. Calculations to synthesize geometries using nodal components use the explicit method. This method overrides Tolerance Angle values if present. • Analysis Type: defines the .cdb file as 3D (default) or 2D. When working with 2D analysis types, make sure that all of your model’s surface normals point in the same direction using the Rigid Transformation properties available through the External Model feature.

Geometry Specifications This feature supports data import of shells or of solids or a mix of shells and solids. See the next section, CDB Import Element Types, for a list of the available element type. For shell bodies that have a constant thickness, Mechanical applies this thickness as a Geometry property. For shell bodies that do not have a constant thickness, Mechanical does not include a thickness

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Specifying Geometry value in the Geometry of the body and the body becomes underdefined; requiring you to enter a Thickness value. In addition, shell offsets are not imported. As a result, shells attach with the Offset Type property set to Middle.

Behaviors and Characteristics Note the following behaviors and characteristics for importing mesh-based geometries: • Geometry construction is for 3D solids and shells and 2D planar bodies only. Mechanical ignores any other element types contained in the .cdb file. • Mechanical only processes node-based components when attempting to create Named Selections for the faces. The application ignores element components. • You cannot change the meshes. That is, you cannot change, clear, or re-mesh once the file has been imported into Mechanical. • Mesh controls (Mesh Numbering, Refinement, etc.) are not supported. • Adaptive Mesh Refinement is not supported. • Geometry is not associative. As a result, if you update the environment, for example, by adding another .cdb file, any scoping that you have performed on an object will be lost. To avoid losses to your analysis environment, make sure that you have properly defined the imported Named Selections or criterion-based Named Selections. • The Stiffness Behavior of bodies can be set to Flexible only. • The Scale Factor Value property on the Geometry object is not supported. Examples of a geometry that results from a synthesis for a given mesh with different Tolerance Angle settings and Nodal Component Key specifications are illustrated below. Meshed Model This illustration is a graphical representation from Mechanical of the node data provided by a .cdb file. Two nodal components have been processed: CylinderNodes and SideNodes.

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Mesh-Based Geometry

45o Tolerance Angle and All Nodal Components Specified This illustration represents a synthesized geometry that includes nodal components and faces created using tolerance angles. The nodal components have overridden the tolerance angles for the SideNodes and created one large face around the geometry and the tolerance angle of 45o has caused the top faces to become merged.

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Specifying Geometry

45o Tolerance Angle and No Nodal Components Specified This illustration shows that when nodal components are not processed, the tolerance angle creates faces correctly around the side of the geometry. However, the tolerance angle of 45o once again has caused the top faces to become merged.

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Mesh-Based Geometry

25o Tolerance Angle and No Nodal Components Specified Here again nodal components are not processed but the tolerance angle has been reduced. This has resulted in a total of 27 faces being created. Note that although the chamfer faces on the top are correctly recovered, the cylinder is now made up of multiple faces.

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Specifying Geometry

25o Tolerance Angle and Cylinder Nodal Component Specified In this illustration, the CylinderNodes Nodal Component Key was specified in the properties and the Tolerance Angle was again fine-tuned to 25o. This has resulted in an accurate synthesis of the geometry.

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Mesh-Based Geometry

180o Tolerance Angle and All Nodal Components Specified This example illustrates the geometry that is synthesized using only nodal components. The tolerance angle is essentially negligible.

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Specifying Geometry

180o Tolerance Angle and No Nodal Components Specified This example illustrates how only one face is generated for the geometry when no tolerance angle (180o) is specified and no nodal components are processed. This type of result can also occur when a nodal component contains all of the nodes for a given body.

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Mesh-Based Geometry

CDB Import Element Types The following element types are supported when .cdb files are processed via the External Model system. Shape Category

Supported Mechanical APDL Element Type

2-D Linear Quadrilateral

PLANE131, PLANE251, FLUID291, PLANE551, PLANE751, INFIN1101, PLANE1621, PLANE1821, INTER192, INTER202, CPT2121

3-D Linear Quadrilateral

SHELL28, SHELL411, SHELL1311, SHELL1571, SHELL1631, SHELL1811

2-D Quadratic Triangle

PLANE35

2-D Quadratic Quadrilateral

PLANE531, PLANE771, PLANE781, PLANE831, INFIN1101, PLANE1211, PLANE1831, INTER193, INTER203, CPT2131, PLANE2231, PLANE2301, PLANE2331

3-D Quadratic Quadrilateral

SHELL1321, SHELL1571, SHELL2811

Quadratic Tetrahedral

SOLID87, SOLID98, SOLID123, SOLID168, SOLID187, CPT217, SOLID227, SOLID232, SOLID237, SOLID285

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Specifying Geometry Shape Category

Supported Mechanical APDL Element Type

Linear Hexahedral

SOLID51, FLUID301, SOLID651, SOLID701, SOLID961, SOLID971, INFIN1111, SOLID1641,SOLID1851, SOLSH1901, INTER195, CPT2151

Quadratic Hexahedral

SOLID901, INFIN1111, SOLID1221, SOLID1861, INTER194, INTER204, CPT2161, SOLID2261, SOLID2311, SOLID2361

Meshing Facet

MESH200

[1] This element supports multiple shapes. This list displays the elements in their most basic and fundamental form

Assembling Mechanical Models You can assemble multiple meshed models from the Workbench Project tab using the Mechanical Model component system, analysis type systems, and/or the External Model component system. That is, you can create multiple meshed model systems that link to one analysis environment that includes all of the individual model files. Examples of this feature are illustrated below. Model cells are linked (Model-to-Model linking). You must first mesh all of the upstream systems in order to open the models in Mechanical. Assembling Mechanical Model Systems

Assembling Mechanical Model Systems and Analysis Systems

Assembling Mechanical Model Systems and External Model Systems

Linked Model Common Properties Similar to importing mesh-based .cdb files using the External Model component system or defining Mesh-to-Mesh Connections, Model-to-Model linking provides certain Project Schematic properties for

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Assembling Mechanical Models the downstream Model cell prior to import; including: geometry length units, the number of copies of the source mesh to transform, and Rigid Transformation properties based on source locations.

Mechanical Model Systems and Analysis Systems Upstream Mechanical Model systems and analysis systems define the engineering data, geometry, and meshes for the assembled or downstream Mechanical Model system or the analysis system. The downstream analysis system can modify any existing specifications to the models once opened in Mechanical. For example, any suppressed bodies coming in from upstream systems can be unsuppressed and remeshed in the downstream environment. Once the models are imported into Mechanical, all application features are available. Limitations and Restrictions for Model Assembly Please note the following requirements for Model Systems: • Parts are made up of one or more bodies. As a result, when working with model systems, the application treats meshed parts and meshed bodies differently with regards to whether the mesh is transferred to the downstream system. Bodies meshed in an upstream system always transfer the mesh to the downstream system. However, parts (single-body or multi-body) meshed and suppressed later in an upstream system; do not have their mesh transferred to the downstream system. Consequently, when the downstream system supports unsuppression, any unsuppressed parts require you to generate a new mesh (unlike an unsuppressed body). • Geometry is not associative. As a result, if you refresh upstream model data into the downstream system, any scoping that you have performed on an object in the downstream analysis will be lost. To avoid losses to your analysis environment, make sure that you have properly defined any imported Named Selections or criterion-based Named Selections. • The Geometry object property Scale Factor Value, allows you to modify the size of imported geometries in the upstream systems. The scale factor value of newly imported geometries is 1.0. You can modify the value and that modified value is expected to be preserved on updated models.

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Specifying Geometry Be aware that when you assemble models and change the associated unit of measure, you are limited by a scale factor limit of 1e-3 to 1e3. This scale factor limit is the limit for any combination of models. Factor values are totaled and anything outside of this range is ignored. As a result, due to these tolerances, scaled models, especially larger and/or combined models, sometimes have problems importing geometry/mesh. • You need to perform material assignment in the upstream systems. The Material category property, Assignment, in the downstream system is read-only. • Model systems do not support the following features. If present, updates to the project fail for the system transferring data to a downstream system. You need to suppress or delete these features before transferring data. – Line Bodies (need to be deleted from geometry) – Rigid Bodies – Gaskets – Crack Objects – Interface layers Imported from ACP – Cyclic Symmetry – Mesh Connections – Virtual Topology You may wish to refer to the Mechanical Model section of the Workbench Help for additional information about this Workbench component system.

External Model Component System When an External Model component system is incorporated into model-to-model assembly, certain restrictions arise. Any suppressed bodies from other upstream systems can be unsuppressed in the downstream environment provided they were meshed prior to being suppressed in the upstream system. However, suppressed parts from other upstream systems can never be unsuppressed in the downstream environment when using the External Model component system. These restrictions also apply when using the options Unsuppress All Bodies and/or Invert Suppressed Body Set. See the Mesh-Based Geometry section of the Mechanical Help for additional specification requirements for working with .cdb files as well as the External Model component system in the Workbench Help.

Associativity of Properties During model assembly, the properties assigned to bodies in upstream systems are automatically transferred to the downstream systems. For multi-body parts, although the properties assigned to each body are transferred, the properties assigned to the parts themselves are not transferred. During refresh operations, when upstream data is modified and the downstream system is refreshed, the properties assigned to bodies in the downstream system are automatically updated, with the following exceptions: • Name • Suppression state 400

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Rigid Bodies • Shell Thickness • Shell Offset These properties do not update if you modify them in the downstream system.

Note It is recommended that you define all mesh controls and settings in your upstream systems. Mesh settings on upstream systems take priority over any downstream mesh settings. That is, any changes to an upstream system will overwrite your mesh setting changes on your downstream system once updated. As a result, you could see differences between the assembled mesh and the settings of the downstream meshed model. Therefore, to have your downstream mesh to be updated per the mesh setting changes, you need to re-mesh your downstream model once it has been refreshed. Mesh transfer will fail on assembled models if mesh controls are present in the downstream system. As needed, you can define mesh controls on the downstream system once you have assembled the model.

Rigid Bodies You can declare the stiffness behavior of a single solid body (a body that is not a component of a multibody part), a body group, surface bodies, and 2D models to be rigid or flexible. A rigid body will not deform during the solution. This feature is useful if a mechanism has only rigid body motion or, if in an assembly, only some of the parts experience most of the strains. It is also useful if you are not concerned about the stress/strain of that component and wish to reduce CPU requirements during meshing or solve operations. To set the stiffness behavior in the Mechanical application 1.

Select a body in the tree.

2.

In the Details view, set Stiffness Behavior to Rigid or Flexible.

To define a rigid body, set the field of the Details view to Rigid when the body object is selected in the tree. If rigid, the body will not be meshed and will internally be represented by a single mass element during the solution. (The mass element’s mass and inertial properties will be maintained.) The mass, centroid, and moments of inertia for each body can be found in the Details view of the body object. The following restrictions apply to rigid bodies: • Rigid bodies are only valid in static structural, Transient Structural, Rigid Dynamics, and modal analyses for the objects listed below. Animated results are available for all analysis types except modal. – Point mass – Joint – Spring – Remote Displacement

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Specifying Geometry – Remote Force – Moment – Contact • Rigid bodies are valid when scoped to solid bodies, surface bodies, or line bodies in Explicit Dynamics Analysis (p. 155) for the following objects: – Fixed Support – Displacement – Velocity The following outputs are available for rigid bodies, and are reported at the centroid of the rigid body: • Results: Displacement, Velocity, and Acceleration • Probes: Deformation, Position, Rotation, Velocity, Acceleration, Angular Velocity, and Angular Acceleration

Note • If you highlight Deformation results in the tree that are scoped to rigid bodies, the corresponding rigid bodies in the Geometry window are not highlighted. • You cannot define a line body, 2D plane strain body, or 2D axisymmetric body as rigid, except that in an Explicit Dynamics analysis, 2D plane strain and 2D axisymmetric bodies may be defined as rigid. • All bodies in a body group (of a multibody part) must have the same Stiffness Behavior. When Stiffness Behavior is Rigid, the body group acts as one rigid mass regardless of whether or not the underlying bodies are topologically connected (via shared topology).

2D Analyses The Mechanical application has a provision that allows you to run structural and thermal problems that are strictly two-dimensional (2D). For models and environments that involve negligible effects from a third dimension, running a 2D simulation can save processing time and conserve machine resources. You can specify a 2D analysis only when you attach a model. Once attached, you cannot change from a 2D analysis to a 3D analysis or vice versa. You can configure Workbench for a 2D analysis by: 1.

Creating or opening a surface body model in DesignModeler or opening a surface body model in any supported CAD system that has provisions for surface bodies. The model must be in the x-y plane. 2D planar bodies are supported; 2D wire bodies are not.

2.

Then, with the Geometry cell selected in the Project Schematic, expose the properties details of the geometry using the toolbar View drop-down menu, and choose 2D in the Analysis Type drop-down menu (located under Advanced Geometry Options).

3.

Attach the model into the Mechanical application by double-clicking on the Model cell.

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2D Analyses A 2D analysis has the following characteristics: • For Geometry items in the tree, you have the following choices located in the 2D Behavior field within the Details view: – Plane Stress (default): Assumes zero stress and non-zero strain in the z direction. Use this option for structures where the z dimension is smaller than the x and y dimensions. Example uses are flat plates subjected to in-plane loading, or thin disks under pressure or centrifugal loading. A Thickness field is also available if you want to enter the thickness of the model. – Axisymmetric: Assumes that a 3D model and its loading can be generated by revolving a 2D section 360o about the y-axis. The axis of symmetry must coincide with the global y-axis. The geometry has to lie on the positive x-axis of the x-y plane. The y direction is axial, the x direction is radial, and the z direction is in the circumferential (hoop) direction. The hoop displacement is zero. Hoop strains and stresses are usually very significant. Example uses are pressure vessels, straight pipes, and shafts. – Plane Strain: Assumes zero strain in the z direction. Use this option for structures where the z dimension is much larger than the x and y dimensions. The stress in the z direction is non-zero. Example uses are long, constant, cross-sectional structures such as structural line bodies. Plane Strain behavior cannot be used in a thermal analysis (steady-state or a transient).

Note Since thickness is infinite in plane strain calculations, different results (displacements/stresses) will be calculated for extensive loads (that is, forces/heats) if the solution is performed in different unit systems (MKS vs. NMM). Intensive loads (pressure, heat flux) will not give different results. In either case, equilibrium is maintained and thus reactions will not change. This is an expected consequence of applying extensive loads in a plane strain analysis. In such a condition, if you change the Mechanical application unit system after a solve, you should clear the result and solve again.

– Generalized Plane Strain: Assumes a finite deformation domain length in the z direction, as opposed to the infinite value assumed for the standard Plane Strain option. Generalized Plane Strain provides more practical results for deformation problems where a z direction dimension exists, but is not considerable. See Using Generalized Plane Strain (p. 404) for more information. Generalized Plane Strain needs the following three types of data: → Fiber Length: Sets the length of the extrusion. → End Plane Rotation About X: Sets the rotation of the extrusion end plane about the x-axis. → End Plane Rotation About Y: Sets the rotation of the extrusion end plane about the y-axis. – By Body: Allows you to set the Plane Stress (with Thickness option), Plane Strain, or Axisymmetric options for individual bodies that appear under Geometry in the tree. If you choose By Body, then click on an individual body, these 2D options are displayed for the individual body. • For a 2D analysis, use the same procedure for applying loads and supports as you would use in a 3D analysis. The loads and results are in the x-y plane and there is no z component.

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Specifying Geometry • You can apply all loads and supports in a 2D analysis except for the following: Line Pressure, Simply Supported, and Fixed Rotation. • A Pressure load can only be applied to an edge. • A Bearing Load and a Cylindrical Support can only be applied to a circular edge. • For analyses involving axisymmetric behavior, a Rotational Velocity load can only be applied about the y-axis. • For loads applied to a circular edge, the direction flipping in the z axis will be ignored. • Only Plain Strain and Axisymmetric are supported for Explicit Dynamics analyses. • Mechanical does not support Cyclic results for a 2D Analysis.

Using Generalized Plane Strain This feature assumes a finite deformation domain length in the z direction, as opposed to the infinite value assumed for standard plane strain. It provides a more efficient way to simulate certain 3D deformations using 2D options. The deformation domain or structure is formed by extruding a plane area along a curve with a constant curvature, as shown below. Y Starting Plane

Starting Point Ending Plane X Fiber Direction Z

Ending Point

The extruding begins at the starting (or reference) plane and stops at the ending plane. The curve direction along the extrusion path is called the fiber direction. The starting and ending planes must be perpendicular to this fiber direction at the beginning and ending intersections. If the boundary conditions and loads in the fiber direction do not change over the course of the curve, and if the starting plane and ending plane remain perpendicular to the fiber direction during deformation, then the amount of deformation of all cross sections will be identical throughout the curve, and will not vary at any curve position in the fiber direction. Therefore, any deformation can be represented by the deformation on the starting plane, and the 3D deformation can be simulated by solving the deformation problem on the starting plane. The Plane Strain and Axisymmetric options are particular cases of the Generalized Plane Strain option. All inputs and outputs are in the global Cartesian coordinate system. The starting plane must be the xy plane, and must be meshed. The applied nodal force on the starting plane is the total force along the fiber length. The geometry in the fiber direction is specified by the rotation about the x-axis and y-axis of the ending plane, and the fiber length passing through a user-specified point on the starting plane called the starting or reference point. The starting point creates an ending point on the ending plane through the extrusion process. The boundary conditions and loads in the fiber direction are specified by applying displacements or forces at the ending point.

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Symmetry The fiber length change is positive when the fiber length increases. The sign of the rotation angle or angle change is determined by how the fiber length changes when the coordinates of the ending point change. If the fiber length decreases when the x coordinate of the ending point increases, the rotation angle about y is positive. If the fiber length increases when the y coordinate of the ending point increases, the rotation angle about x is positive. For linear buckling and modal analyses, the Generalized Plane Strain option usually reports fewer Eigenvalues and Eigenvectors than you would obtain in a 3D analysis. Because it reports only homogeneous deformation in the fiber direction, generalized plane strain employs only three DOFs to account for these deformations. The same 3D analysis would incorporate many more DOFs in the fiber direction. Because the mass matrix terms relating to DOFs in the fiber direction are approximated for modal and transient analyses, you cannot use the lumped mass matrix for these types of simulations, and the solution may be slightly different from regular 3D simulations when any of the three designated DOFs is not restrained. Overall steps to using Generalized Plane Strain 1.

Attach a 2D model in the Mechanical application.

2.

Click on Geometry in the tree.

3.

In the Details view, set 2D Behavior to Generalized Plane Strain.

4.

Define extrusion geometry by providing input values for Fiber Length, End Plane Rotation About X, and End Plane Rotation About Y.

5.

Add a Generalized Plane Strain load under the analysis type object in the tree.

Note The Generalized Plane Strain load is applied to all bodies. There can be only one Generalized Plane Strain load per analysis type so this load will not be available in any of the load drop-down menu lists if it has already been applied.

6.

In the Details view, input the x and y coordinates of the reference point , and set the boundary conditions along the fiber direction and rotation about the x and y-axis.

7.

Add any other loads or boundary conditions that are applicable to a 2D model.

8.

Solve. Reactions are reported in the Details view of the Generalized Plane Strain load.

9.

Review results.

Symmetry You can use the inherent geometric symmetry of a body to model only a portion of the body for simulation. Using symmetry provides the benefits of faster simulation times and less use of system resources. For example, the model below can be simplified by modeling only ¼ of the geometry by taking advantage of two symmetry planes.

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Introduction Making use of the Symmetry feature requires an understanding of the geometry symmetry and the symmetry of loading and boundary conditions. If geometric symmetry exists, and the loading and boundary conditions are suitable, then the model can be simplified to just the symmetry sector of the model. DesignModeler can be used to simplify a full model into a symmetric model. This is done by identifying symmetry planes in the body. DesignModeler will then slice the full model and retain only the symmetry portion of the model. (See Symmetry in the DesignModeler help). To further understand the use of Symmetry in the Mechanical application, examine the following topics: Types of Regions Symmetry Defined in DesignModeler Symmetry in the Mechanical Application

Types of Regions When the Mechanical application attaches to a symmetry model from DesignModeler, a Symmetry folder is placed in the tree and each Symmetry Plane from DesignModeler is given a Symmetry Region object in the tree. In addition, Named Selection objects are created for each symmetry edge or face. (See Symmetry Defined in DesignModeler (p. 425).) The Symmetry folder supports the following objects: • Symmetry Region – supported for structural analyses. • Periodic Region – supported for magnetostatic analyses.

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Symmetry • Cyclic Region – supported for structural and thermal analyses.

Note Periodic and Cyclic regions: • Support 3D analyses only • Ensure that a mesh is cyclic and suitable for fluids analyses (the mesh is then matched, however, users must re-assign periodic regions in the solver).

For models generated originally as symmetry models, you may create a Symmetry folder and manually identify Symmetry Region objects or Periodic/Cyclic Region objects. (See Symmetry in the Mechanical Application (p. 426).)

Symmetry Region A symmetry region refers to dimensionally reducing the model based on a mirror plane. Symmetry regions are supported for: • Structural Symmetry • Structural Anti-Symmetry • Structural Linear Periodic Symmetry • Electromagnetic Symmetry • Electromagnetic Anti-Symmetry • Explicit Dynamics Symmetry

Structural Symmetry A symmetric structural boundary condition means that out-of-plane displacements and in-plane rotations are set to zero. The following figure illustrates a symmetric boundary condition. Structural symmetry is applicable to solid and surface bodies.

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Structural Anti-Symmetry An anti-symmetric boundary condition means that the rotation normal to the anti-symmetric face is constrained. The following figure illustrates an anti-symmetric boundary condition. Structural antisymmetry is applicable to solid and surface bodies.

Note The Anti-Symmetric option does not prevent motion normal to the symmetry face. This is appropriate if all loads on the structure are in-plane with the symmetry plane. If applied loads, or loads resulting from large deflection introduce force components normal to the face, an additional load constraint on the normal displacement may be required.

Structural Linear Periodic Symmetry The Linear Periodic Boundary condition is used to simulate models with translational symmetry, where the structure is assumed to repeat itself in one particular direction to infinity. This feature supports only a single direction for the entire model (more than one direction is not supported). The application uses the MAPDL command CE to solve this boundary condition.

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Electromagnetic Symmetry Symmetry conditions exist for electromagnetic current sources and permanent magnets when the sources on both sides of the symmetry plane are of the same magnitude and in the same direction as shown in the following example.

Electromagnetic symmetric conditions imply Flux Normal boundary conditions, which are naturally satisfied.

Electromagnetic Anti-Symmetry Anti-Symmetry conditions exist for electromagnetic current sources and permanent magnets when the sources on both sides of the symmetry plane are of the same magnitude but in the opposite direction as shown in the following example.

Electromagnetic anti-symmetric conditions imply Flux Parallel boundary conditions, which you must apply to selected faces.

Explicit Dynamics Symmetry Symmetry regions can be defined in explicit dynamics analyses. Symmetry objects should be scoped to faces of flexible bodies defined in the model. All nodes lying on the plane, defined by the selected face are constrained to give a symmetrical response of the structure.

Note • Anti-symmetry, periodicity and anti-periodicity symmetry regions are not supported in Explicit Dynamics systems. • Symmetry cannot be applied to rigid bodies.

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Specifying Geometry • Only the General Symmetry interpretation is used by the solver in 2D Explicit Dynamics analyses.

Symmetry conditions can be interpreted by the solver in two ways: General Symmetry Global Symmetry Planes

General Symmetry In general, a symmetry condition will result in degree of freedom constraints being applied to the nodes on the symmetry plane. For volume elements, the translational degree of freedom normal to the symmetry plane will be constrained. For shell and beam elements, the rotational degrees of freedom in the plane of symmetry will be additionally constrained. For nodes which have multiple symmetry regions assigned to them (for example, along the edge between two adjacent faces), the combined constraints associated with the two symmetry planes will be enforced.

Note • Symmetry regions defined with different local coordinate systems may not be combined, unless they are orthogonal with the global coordinate system. • General symmetry does not constrain eroded nodes. Thus, if after a group of elements erodes, a “free” eroded node remains, the eroded node will not be constrained by the symmetry condition. This can be resolved in certain situations via the special case of Global symmetry, described in the next section.

Global Symmetry Planes If a symmetry object is aligned with the Cartesian planes at x=0, y=0 or z=0, and all nodes in the model are on the positive side of x=0, y=0, or z=0, the symmetry condition is interpreted as a special case termed Global symmetry plane. In addition to general symmetry constraints: • If a symmetry plane is coincident with the YZ plane of the global coordinate system (Z=0), and no parts of the geometry lie on the negative side of the plane, then a symmetry plane is activated at X=0. This will prevent any nodes (including eroded nodes) from moving through the plane X=0 during the analysis. • If a symmetry plane is coincident with the ZX plane of the global coordinate system (Y=0), and no parts of the geometry lie on the negative side of the plane, then a symmetry plane is activated at Y=0. This will prevent any nodes (including eroded nodes) from moving through the plane Y=0 during the analysis. • If a symmetry plane is coincident with the XY plane of the global coordinate system (Z=0), and no parts of the geometry lie on the negative side of the plane, then a symmetry plane is activated at Z=0. This will prevent any nodes (including eroded nodes) from moving through the plane Z=0 during the analysis.

Note Global symmetry planes are only applicable to 3D Explicit Dynamics analyses.

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Periodic Region The Periodic Region object is used to define for Electromagnetic analysis Periodical or Anti–Periodical behavior in a particular model (see Electromagnetic Periodic Symmetry section).

Electromagnetic Periodicity A model exhibits angular periodicity when its geometry and sources occur in a periodic pattern around some point in the geometry, and the repeating portion that you are modeling represents all of the sources, as shown below (see the Periodicity Example (p. 412)).

Electromagnetic Anti-Periodicity A model exhibits angular anti-periodicity when its geometry and sources occur in a periodic pattern around some point in the geometry and the repeating portion that you are modeling represents a subset of all of the sources, as shown below.

Electromagnetic Periodic Symmetry Electric machines and generators, solenoid actuators and cyclotrons are just a few examples of numerous electromagnetic devices that exhibit circular symmetrical periodic type of symmetry. An automated periodic symmetry analysis conserves time and CPU resources and delivers analysis results that correspond to the entire structure. The overall procedure in ANSYS Workbench for simulating structures that are periodically symmetric is to run a magnetostatic analysis and perform the following specialized steps:

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Specifying Geometry 1. Insert a Periodic Region symmetry object in the tree. This step is necessary to enable ANSYS Workbench to perform a periodic symmetry analysis. 2. Define the low and high boundaries of the Periodic Region by selecting the appropriate faces in the Low Boundary and High Boundary fields. 3. Define type of symmetry as Periodic or Anti-Periodic (see Periodicity Example (p. 412)). 4. The solver will automatically take into account defined periodicity, and reported results will correspond to the full symmetry model (except volumetric type results as Force Summation, Energy probe, and so on).

Note For a magnetic field simulation with periodic regions, you must be careful when applying flux parallel boundary conditions to adjoining faces. If the adjoining faces of the periodic faces build up a ring and all are subject to flux parallel conditions, that implies a total flux of zero through the periodic face. In some applications that is not a physically correct requirement. One solution is to extend the periodic sector to include the symmetry axis.

See the Periodicity Example (p. 412) section for further details.

Periodicity Example Periodicity is illustrated in the following example. A coil arrangement consists of 4 coils emulated by stranded conductors. A ½ symmetry model of surrounding air is created. The model is conveniently broken into 16 sectors for easy subdivision into periodic sectors and for comparison of results.

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Symmetry Below is a display of the Magnetic Field Intensity for the ½ symmetry model at the mid-plane. The arrows clearly indicate an opportunity to model the domain for both Periodic or Anti-periodic sectors. Periodic planes are shown to exist at 180 degree intervals. Anti-periodic planes are shown to exist at 90 degree intervals.

The model can be cut in half to model Periodic planes. Applying periodic symmetry planes at 90 degrees and 270 degrees leads to the following results.

The model can be cut in half again to model Anti-Periodic planes. Applying anti-periodic symmetry planes at 0 degrees and 90 degrees leads to the following results.

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Cyclic Region Fan wheels, spur gears, and turbine blades are all examples of models that can benefit from cyclic symmetry. An automated cyclic symmetry analysis conserves time and CPU resources and allows you to view analysis results on the entire structure (for a structural analysis). ANSYS Workbench automates cyclic symmetry analysis by: • Solving for the behavior of a single symmetric sector (part of a circular component or assembly). See The Basic Sector in the Advanced Analysis Guide for more information. • Using the single-sector solution to construct the response behavior of the full circular component or assembly (as a postprocessing step). For example, by analyzing a single 10° sector of a 36-blade turbine wheel assembly, you can obtain the complete 360° model solution via simple postprocessing calculations. Using twice the usual number of degrees of freedom (DOFs) in this case, the single sector represents a 1/36th part of the model.

Note • Layered Sections cannot be applied to a model that uses cyclic symmetry. • Mechanical 2D Analyses do not support cyclic results.

The overall procedure in ANSYS Workbench for simulating models that are cyclically symmetric is to run a static structural, modal, or thermal analysis and perform the following specialized steps: 1. Insert a Cyclic Region symmetry object in the tree. This step is necessary to enable ANSYS Workbench to perform a cyclic symmetry analysis. Multiple Cyclic Region objects are permitted but they must refer to the same Coordinate System to specify the symmetry axis. 2. Define the low and high boundaries of the Cyclic Region by selecting the appropriate faces in the Low Boundary and High Boundary fields. Each selection can consist of one or more faces over one or more parts, but they must be paired properly. To be valid, each face in Low Boundary must be accompanied by its twin in High Boundary. Also, ensure that each face and its twin belong to the same multibody part (although it is not necessary that they belong to the same body), using DesignModeler to adjust your multibody parts as needed. Your selections will be used to match the mesh of these two boundaries. The example shown below illustrates two equally valid Low Boundary and High Boundary twin faces. One twin set of faces, located in the corner body, includes faces that are both included in that same body. Another twin set includes faces that are not on the same body, but are included in the same multibody part, as shown in the second figure.

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Note High Boundary and Low Boundary should be exactly same in shape and size, otherwise Mechanical will not be able to map nodes from Low Boundary to High Boundary to create full model from a single sector.

3. Continue with the remainder of the analysis. Consult the sections below as applicable to the analysis type. Refer to the following sections for further details on cyclic symmetry: Cyclic Symmetry in a Static Structural Analysis Cyclic Symmetry in a Modal Analysis Cyclic Symmetry in a Thermal Analysis

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Cyclic Symmetry in a Static Structural Analysis When you perform a static structural analysis that involves cyclic symmetry, unique features are available for loads/supports and reviewing results. These features are described in the following sections: Applying Loads and Supports for Cyclic Symmetry in a Static Structural Analysis Reviewing Results for Cyclic Symmetry in a Static Structural Analysis

Applying Loads and Supports for Cyclic Symmetry in a Static Structural Analysis The following support limitations and specifications must be observed: • The following boundary conditions are not supported: – Bearing Load – Hydrostatic Pressure – Fluid Solid Interface • The following remote boundary conditions are not supported: – Joints – Bearing • Inertial boundary conditions and the Moment boundary condition are restricted to the axial direction. To comply, Acceleration, Standard Earth Gravity, Rotational Velocity, and Moment must be defined by components: only the Z component can be non-zero and the Coordinate System specified must match that used in the Cyclic Region. Additional restrictions apply while specifying supports for a static structural analysis. For example, Elastic Supports and Compression Only Supports are not available. Also, the loads and supports should not include any face selections (for example, on 3D solids) that already belong to either the low or high boundaries of the cyclic symmetry sector. Loads and supports may include edges (for example, on 3D solids) on those boundaries, however.

Note If you scope a Remote Force or Moment boundary condition to a Remote Point that is located on the cyclic axis of symmetry, it is necessary that the Remote Point be constrained by a Remote Displacement in order to obtain accurate results. Furthermore, non-physical results might be exposed if the remote boundary conditions specify the Behavior option as Deformable. Loads and supports are assumed to have the same spatial relation for the cyclic axis in all sectors. In preparation for solution, the boundary conditions on the geometry are converted into node constraints in the mesh (see Converting Boundary Conditions to Nodal DOF Constraints (Mechanical APDL Solver) (p. 1135) for more information). When these boundary conditions involve nodes along the sector boundaries (low, high, and axial boundaries), their constraints are integrated to properly reflect the symmetry. As an example, the low and high edges may feature more node constraints than are applied to each individually, in order to remain consistent with an equivalent full model.

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Reviewing Results for Cyclic Symmetry in a Static Structural Analysis When simulating cyclic symmetry in a static structural analysis, the same results are available as results in static structural analyses that involve full symmetry with the exception of Linearized Stresses. Even though only one cyclic sector is analyzed, results are valid for the full symmetry model. You can control the post-processing and display of cyclic results using the Cyclic Solution Display options on the Solution folder: • Number of Sectors: This option controls the extent the model is expanded from the raw solution. The value indicates how many sectors should be processed, displayed and animated. Results generate more quickly and consume less memory and file storage when fewer sectors are requested. To set the value as Program Controlled, enter zero; this value reveals the full expansion. • Starting at Sector: Selects the specific sectors to include within the expansion. For example, if Number of Sectors is set to 1, sectors 1 through N are revealed one at a time. To set the value as Program Controlled, enter zero; this value reveals the specified number of sectors from sector 1 onwards.

Note Extremum values (e.g., Minimum, Maximum) correspond only to the portion of the model selected in the Cyclic Solution Display. Unexpanded One Sector Model Display:

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Specifying Geometry Expanded Full Symmetry Model Display:

Note • The results for the Energy Probe, Force Reaction probe, and Moment Reaction probe are calculated for the full symmetry model. • Unaveraged contact results do not expand to all expanded sectors in a cyclic analysis. • Expanded result visualization is not available to the Samcef solver.

Cyclic Symmetry in a Modal Analysis When you perform a modal analysis that involves cyclic symmetry, unique features are available for loads/supports, analysis settings, and reviewing results. These features are described in the following sections: Applying Loads and Supports for Cyclic Symmetry in a Modal Analysis Analysis Settings for Cyclic Symmetry in a Modal Analysis Reviewing Results for Cyclic Symmetry in a Modal Analysis

Applying Loads and Supports for Cyclic Symmetry in a Modal Analysis The following support limitations and specifications must be observed: • Elastic Supports and Compression Only Supports are not permitted. 418

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Symmetry • Supports should not include any face selections (for example, on 3D solids) that already belong to either the low or high boundaries of the cyclic symmetry sector. Supports may include edges (for example, on 3D solids) on those boundaries, however. • Only the following remote boundary conditions are supported: – Remote Displacement – Point Mass – Spring In preparation for solution, the boundary conditions on the geometry are converted into node constraints in the mesh (see Converting Boundary Conditions to Nodal DOF Constraints (Mechanical APDL Solver) (p. 1135) for more information). When these boundary conditions involve nodes along the sector boundaries (low, high and axial boundaries), their constraints are integrated to properly reflect the symmetry. As an example, the low and high edges may feature more node constraints than are applied to each individually, in order to remain consistent with an equivalent full model. If the modal analysis is activated as pre-stressed, no other modal loads/supports are allowed. On the other hand you can apply all pertinent structural loads/supports in the previous cyclic static analysis. When using the Samcef solver, compatibility of supports with cyclic symmetry is checked internally. If an incompatibility is detected a warning or error message will be displayed, and the solve will be interrupted.

Analysis Settings for Cyclic Symmetry in a Modal Analysis A modal analysis involving cyclic symmetry includes a Cyclic Controls (p. 646) category that enables you to solve the harmonic index for all values, or for a range of values. This category is available if you have defined a Cyclic Region in the analysis.

Note Currently for Modal Analysis with Cyclic Symmetry: • The Unsymmetric Solver Type (UNSYM) is not supported. • Damping is not supported (Fully Damped, DAMPED, or Reduced Damped, QRDAMP). • Expansion is only available for harmonic indices > 0 with the Samcef solver. For more information about the associated MAPDL command, see the MODOPT section of the Mechanical APDL Command Reference.

Reviewing Results for Cyclic Symmetry in a Modal Analysis A modal analysis involving cyclic symmetry includes additional options to help you navigate and interpret the results. In particular, there are features to: • Review the complete range of modes: you may request the modes to be sorted by their serial number in the results file or by their frequency value in the spectrum. • Review combinations of degenerate modes through the complete range of phase angles. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Specifying Geometry When simulating cyclic symmetry in a modal analysis, the same results are available as for a modal analysis with full symmetry, with the exception of Linearized Stresses. Although only one cyclic sector is analyzed, results are valid for the full symmetry model. You can control the post-processing and display of cyclic results using the Cyclic Solution Display options on the Solution folder: • Number of Sectors: This option controls the extent the model is expanded from the raw solution. The value indicates how many sectors should be processed, displayed and animated. Results generate more quickly and consume less memory and file storage when fewer sectors are requested. To set the value as Program Controlled, enter zero; this value reveals the full expansion. • Starting at Sector: Selects the specific sectors to include within the expansion. For example, if Number of Sectors is set to 1, sectors 1 through N are revealed one at a time. To set the value as Program Controlled, enter zero; this value reveals the specified number of sectors from sector 1 onwards.

Note Extremum values (e.g., Minimum, Maximum) correspond only to the portion of the model selected in the Cyclic Solution Display. Because these features involve reviewing the mode shapes and contours at individual points within a range, they leverage the charting facilities of the Graph and Tabular Data windows together with the 3D contour plotting of the Graphics view. Reviewing the Complete Range of Modes You may request the modes to be sorted in the Graph window by their set number in the results file or by their frequency value in the spectrum. You may then interact with the plot to generate specific mode shapes and contours of interest. To control how modes are sorted, use the X-Axis setting under Graph Controls in the Details view of the result and set to either Mode or Frequency: • Mode: This choice will designate the x-axis in the Graph window to indicate the set numbers for each mode (within a harmonic index) in the results file. Each mode will have a vertical bar whose height represents its frequency of vibration. The columns in the Tabular Data window are displayed in the order of: Mode, Harmonic Index, and Frequency.

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When X-Axis is set to Mode, the Definition category includes settings for Cyclic Mode and Harmonic Index. • Frequency: This choice will designate the x-axis in the Graph window to indicate the mode Frequency. Modes are thus sorted by their frequencies of vibration. Each mode will have a vertical bar whose height, for cross-reference, corresponds to the mode number (within its harmonic index). The columns in the Tabular Data window are displayed in the order of: Frequency, Mode, and Harmonic Index.

When X-Axis is set to Frequency, the Definition category includes a setting for Cyclic Phase. Readonly displays of the Minimum Value Over Phase and the Maximum Value Over Phase are also available. • Phase: For degenerate modes or couplets, a third option for the X-Axis setting under Graph Controls is available. This choice will designate the x-axis in the Graph window to indicate the phase angle. The graph will show the variation of minimum and maximum value of the result with change in phase angle for the concerned couplet. This setting allows you to analyze the result for a particular mode (for couplets only). The columns in the Tabular Data window are displayed in the order of: Phase, Minimum and Maximum. For details on couplets, read the section below. Reviewing results for frequency couplets as a function of cyclic phase angles An inspection of the results for harmonic indices between 0 and N/2 (that is, 0 < Harmonic Index < N/2) reveals that natural frequencies are reported in pairs by the solver. These pairs of equal value are often Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Specifying Geometry termed “couplets”. The corresponding mode shapes in each couplet represent two standing waves, one based on a sine and another on a cosine solution of the same spatial frequency, thus having a phase difference of 90°. To appreciate the full range of vibrations possible at a given frequency couplet, it is necessary to review not only the individual mode shapes for sine and cosine (e.g., at 0° and 90°) but also their linear combinations which sweep a full cycle of relative phases from 0° to 360°. This sweep is displayed by Mechanical as an animation called a "traveling wave". The following is an example:

Note The following demos are presented in animated GIF format. Please view online if you are reading the PDF version of the help.

Animations for mode shapes in other harmonic indices, that is, 0 or, for N even, N/2, will yield standing waves. The following animation is an example of a standing wave.

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Symmetry

There are options to review the dependence of a result on cyclic phase angle quantitatively. For applicable harmonic indices, results can be defined by: • Cyclic Phase: Use in combination with the Cyclic Phase setting to report the contour at a specific phase. Under this setting, the result will also report the Minimum Value Over Cyclic Phase and the Maximum Value Over Cyclic Phase. • Maximum over Cyclic Phase: this contour reveals the peak value of the result as a function of cyclic phase for every node/element. • Cyclic Phase of Maximum: this contour reveals the cyclic phase at which the peak value of the result is obtained for every node/element. When the result is defined by Cyclic Phase, it may be convenient to use the interaction options to pick the value of phase from the Tabular Data window as an alternative to direct input in the Details view. To access this feature, set the X-Axis to Phase under Graph Controls. To control the density of the cyclic phase sweep, choose Tools> Options from the main menu, then under Mechanical choose Frequency and Cyclic Phase Number of Steps. The phase sweep can be disabled individually on a result by setting Allow Phase Sweep to No in the Details view.

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Interaction Options The Graph, Tabular Data and the Graphics view can be used in concert while reviewing modal cyclic results. For example, if you click in the Tabular Data window, a black vertical cursor moves to the corresponding position in the chart. Conversely, if you click on a bar (for Mode or Frequency display) or a node in the chart (for a Phase display), the corresponding row is highlighted in the Tabular Data window. Multi-selection is also available by dragging the mouse over a range of bars or nodes (in the chart) or rows in the Tabular Data window. These are useful in identifying the mode number and harmonic index with specific values of the frequency spectrum.

Also, the Graph or Tabular Data windows can be used to request a specific mode shape at a phase value of interest (if applicable) using context sensitive options. To access these, select an item in the Graph or Tabular Data windows and click the right mouse button. The following are the most useful options: • Retrieve This Result: Auto-fills the Mode and Harmonic Index ( for a Mode or Frequency display) or the Phase angle (for a Phase display) into the Details view of the result and will force the evaluation of the result with the parameters that were recently changed. • Create Mode Shape Results: processes the selected pairs (Mode, Harmonic Index defined by dragging in the Graph window to produce a light blue rectangle) and inserts results under the Solution folder. You must then evaluate these results, since they are not evaluated automatically. This option is not available for Phase display. The following two options are available only if you click the right mouse button in the Graph window:

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Symmetry • Zoom to Range: Zooms in on a subset of the data in the Graph window. Click and hold the left mouse at a step location and drag to another step location. The dragged region will highlight in blue. Next, select Zoom to Range. The chart will update with the selected step data filling the entire axis range. This also controls the time range over which animation takes place. • Zoom to Fit: If you have chosen Zoom to Range and are working in a zoomed region, choosing Zoom to Fit will return the axis to full range covering all steps.

Cyclic Symmetry in a Thermal Analysis When you perform a steady state thermal analysis or transient thermal analysis that involves cyclic symmetry, unique features are available for loads/supports and reviewing results. These features are described in the following sections: Applying Loads for Cyclic Symmetry in a Thermal Analysis Reviewing Results for Cyclic Symmetry in a Thermal Analysis

Applying Loads for Cyclic Symmetry in a Thermal Analysis For a thermal analysis, in the presence of cyclic symmetry, Coupling loads are not available. Also, loads should not include any face selections (for example, on 3D solids) that already belong to either the low or high boundaries of the cyclic symmetry sector. Loads may include edges (for example, on 3D solids) on those boundaries, however. Loads are assumed to have the same spatial relation for the cyclic axis in all sectors. In preparation for solution, the boundary conditions on the geometry are converted into node constraints in the mesh (see Converting Boundary Conditions to Nodal DOF Constraints (Mechanical APDL Solver) (p. 1135) for more information). When these boundary conditions involve nodes along the sector boundaries (low, high and axial boundaries), their constraints are integrated to properly reflect the symmetry. As an example, the low and high edges may feature more node constraints than are applied to each individually, in order to remain consistent with an equivalent full model.

Reviewing Results for Cyclic Symmetry in a Thermal Analysis When simulating cyclic symmetry in a thermal analysis, the same results are available as results in a thermal analysis that involve full symmetry.

Note Radiation Probe results are calculated for the full symmetry model.

Symmetry Defined in DesignModeler The following procedure describes the steps use to working with Symmetry in DesignModeler. 1. While in DesignModeler, from the Tools menu, apply the Symmetry feature to the model or define an Enclosure. 2. Enter the Mechanical application by double-clicking on the Model cell in the Project Schematic. The Mechanical application screen appears and includes the following objects in the tree: • A Symmetry object. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Specifying Geometry • Symmetry Region objects displayed under the Symmetry folder. The number of Symmetry Region objects corresponds to the number of symmetry planes you defined in DesignModeler. • A Named Selections folder object. Each child object displayed under this folder replicates the enclosure named selections that were automatically created when you started the Mechanical application. 3. In the Details view of each Symmetry Region object, under Definition, specify the type of symmetry by first clicking on the Type field, then choosing the type from the drop down list. Boundary conditions will be applied to the symmetry planes based on both the simulation type and what you specify in the symmetry Type field. The Scope Mode read-only indication is Automatic when you follow this procedure of defining symmetry in DesignModeler. The Coordinate System and Symmetry Normal fields include data that was “inherited” from DesignModeler. You can change this data if you wish. The Symmetry Normal entry must correspond to the Coordinate System entry.

Symmetry in the Mechanical Application The following procedure describes the steps that you’ll use to implement feature during an analysis using the Mechanical Application. 1. Insert a Symmetry object in the tree. 2. Insert a Symmetry Region object, a Periodic Region object, or a Cyclic Region object to represent each symmetry plane you want to define. Refer to Symmetry Region (p. 407) to determine which object to insert. 3. For each Symmetry Region object or Periodic/Cyclic Region object, complete the following in the Details view: a. Scoping Method - Perform one of the following: • Choose Geometry Selection if you want to define a symmetry plane by picking in the Geometry window. Pick the geometry, then click on the entry field for Geometry Selection (labeled No Selection) and click the Apply button. For a Periodic/Cyclic Region object or for a Symmetry object whose Type is specified as Linear Periodic, select the appropriate faces/edges in the Low Boundary and High Boundary fields. Each selection can consist of one or more faces over one or more parts, but they must be paired properly. To be valid, each face/edge in Low Boundary must be accompanied by its twin in High Boundary. Also, ensure that each face/edge and its twin belong to the same multibody part (although it is not necessary that they belong to the same body), using DesignModeler to adjust your multibody parts as needed. Your selections will be used to match the mesh of these two boundaries.

Note A Symmetry Region object can only be scoped to a flexible body.

• Choose Named Selection if you want to define a symmetry plane using geometry that was predefined in a named selection. Click on the entry field for Named Selection and, from the drop down list, choose the particular named selection to represent the symmetry plane. For a Periodic/Cyclic Region object, you perform the same procedure, where Low Selection corresponds to the Low Boundary component and High Selection corresponds to the High Boundary component.

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Symmetry b. The Scope Mode read-only indication is Manual when you follow this procedure of defining symmetry directly in the Mechanical application. c. Type - For a Symmetry Region or Periodic Region only, click on the entry field, and, from the drop down list, choose the symmetry type. Boundary conditions will be applied to the symmetry planes based on both the simulation type and the value you specify in the symmetry Type field. d. Coordinate System - Select an appropriate coordinate system from the drop down list. You must use a Cartesian coordinate system for a Symmetry Region. The Periodic/Cyclic Region require a cylindrical coordinate system. See the Coordinate Systems section, Initial Creation and Definition, for the steps to create a local coordinate system. e. Symmetry Normal - For a Symmetry Region object only, specify the normal axis from the drop down list that corresponds to the coordinate system that you chose. f.

Periodicity Direction - For a Linear Periodic Symmetry Region object only. This axis should point into the direction (in user selected Coordinate System) the model should be translated. It might be different from Symmetry Normal property used for other Symmetry Region types.

g. Linear Shift - For a Linear Periodic Symmetry Region object only. This property value (positive or negative) represents the nodes location increments in chosen Periodicity Direction. h. Suppressed - Include (No - default) or exclude (Yes) the boundary condition. The following example shows a body whose Symmetry Region was defined in the Mechanical application.

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Note You can select multiple faces to work with a symmetry region. For Symmetric/Anti-Symmetric Symmetry Regions, all faces selected (or chosen through Named Selection folder) must have only one normal. For periodic/cyclic types, you should additionally choose the proper cylindrical coordinate system with the z-axis showing the rotation direction, similar to the Matched Face Mesh meshing option. For Symmetry Region with Linear Periodic type, you should in turn choose the proper Cartesian coordinate system with the Periodicity Direction and Linear Shift properties showing pertinent values to facilitate conditions similar to the Arbitrary Match Control meshing option. The following example shows a body whose Periodic Region was defined in the Mechanical application.

The following example shows a body whose Cyclic Region was defined in the Mechanical application.

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Named Selections

Note When using a Periodic/Cyclic Region or for a Symmetry object whose Type is specified as Linear Periodic, the mesher automatically sets up match face meshing on the opposite Low Boundary and High Boundary faces. A useful feature available is the ability to swap Low Boundary and High Boundary settings under Scope in the Details view. You accomplish this by clicking the right mouse button on the specific symmetry regions (Ctrl key or Shift key for multiple selections) and choosing Flip High/Low.

Note Except for cyclic symmetry models, symmetry models will not deform for unaveraged results. For example, for an unaveraged stress display, you will see the undeformed shape of the model.

Named Selections The Named Selection feature allows you to create groupings of similar geometry or meshing entities. The section describes the steps to create Named Selections objects and prepare them for data definition. Subsequent sections further define and build upon these techniques, and include: Defining Named Selections Promoting Scoped Objects to a Named Selection Displaying Named Selections Using Named Selections Displaying Interior Mesh Faces Converting Named Selection Groups to Mechanical APDL Application Components

Create a Named Selection Object Creating Named Selections objects is easy and can be accomplished by several different methods, including: • Select the Model object and click the Named Selection button on the Model Context Toolbar or select the Model object, right-click the mouse, and then select Insert>Named Selection.

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• Select desired geometry entities from the Geometry object, right-click the mouse, and then select Create Named Selection. A Selection Name window appears so that you can enter a specific name for the Named Selection.

• Select desired geometry entities in the graphical interface (bodies, faces, etc. - bodies are show below), right-click the mouse, and then select Create Named Selection. A Selection Name window appears so that you can enter a specific name for the Named Selection as well as specify criteria based on the selected geometry.

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Named Selections

As illustrated below, these methods, by default, place a Named Selections folder object into the tree that includes a child object titled Selection or titled with a user-defined name. This new object, and any subsequent named selection objects that are inserted into the parent folder, require geometry or mesh entity scoping. If a direct selection method (via Geometry object or graphical selection) was used, the Geometry entities may already be defined. The Selection objects are the operable “named selections” of your analysis. You may find it beneficial to rename these objects based on the entities to which they are scoped or the purpose that they will serve in the analysis. For example, you may wish to rename a Named Selection containing edges to "Edges for Contact Region".

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Adding Named Selection Objects If a Named Selections folder object exists in the tree, insert additional Named Selection objects using the same general methods as above: (1) click the Named Selection button on the Named Selection context toolbar (available once the Named Selection folder is generated) or (2) when either the Named Selections parent folder object or another Selection object is highlighted, right-click the mouse and select Insert>Named Selection.

Defining Named Selections The following sections describe the methods used to define the characteristics of your Named Selection, such as geometry, and include: Specifying Named Selections by Geometry Type Specifying Named Selections using Worksheet Criteria

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Named Selections

Specifying Named Selections by Geometry Type Once you create Named Selections/Selection objects, you need to define the geometry or node-based meshing entities that you would like to scope to the object. Scoping method options include: • Geometry - geometry-based, node-based, element-based entries/selections • Worksheet - criteria-based entries/selections. Use the steps shown below to define the Details of your Named Selections based on geometry types (body, face, edge, or vertex). To scope your Named Selection to nodes or elements or by using the Worksheet, see one of the following sections: • Specifying Named Selections by Direct Node Selection (p. 101) • Specifying Element-Based Named Selections (p. 104) • Specifying Named Selections using Worksheet Criteria (p. 434)

Named Selections Defined by Geometry Types To define geometry-based named selections: 1. Highlight the Selection object in the tree. In the Details view, set Scoping Method to Geometry Selection. 2. Select the geometry entities in the graphics window to become members of the Named Selection. 3. Click in the Geometry field in the details view, then click the Apply button. The named selection is indicated in the graphics window. You can rename the object by right-clicking on it and choosing Rename from the context menu.

Tip To allow the Named Selection criteria to be automatically generated after a geometry update, highlight the Named Selections folder object and set Generate on Refresh to Yes (default). This setting is located under the Worksheet Based Named Selections category in the Details view.

Note • If you change the Scoping Method from Geometry Selection to Worksheet, the original geometry scoping remains until you select Generate. • For geometric entity Named Selections, the status of a Named Selection object can be fully defined (check mark) only when a valid geometry is applied, or suppressed (“x”) if either no geometry is applied or if all geometry applied to the Named Selection is suppressed. • For a Named Selection created using the Graphics Viewer, the selections must be manually updated after you change the geometry.

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Specifying Named Selections using Worksheet Criteria As described in the Specifying Named Selections by Geometry Type (p. 433) section, you can specify the Worksheet as your Scoping Method. Worksheet data defines the criteria for Named Selections based on geometric or meshing entities. Each row of the worksheet performs a calculation for the specified criteria. If multiple rows are defined, the calculations are evaluated and completed in descending order.

Named Selections Defined by Worksheet Criteria To define named selections using Worksheet criteria: 1. Highlight the Selection object. In the Details view, set Scoping Method to Worksheet. 2. As needed, right-click the mouse and select Add Row. 3. Enter data in the worksheet for specifying the criteria that will define a Named Selection. See the Worksheet Entries and Operation section below for specific entry information. 4. Click the Generate button located on the Worksheet to create the Named Selection based on the specified criteria. Alternatively, you can right-click on the Named Selection object and choose Generate Named Selection from the context menu.

Note • If you change the Scoping Method from Geometry Selection to Worksheet, the original geometry scoping will remain until you select Generate. • When you select Generate and the generation fails to produce a valid selection, any prior scoping is removed and the Named Selection. • If there is no indication that the worksheet has been changed and the Named Selection should be regenerated, you still may want to select Generate to ensure that the item is valid. • If a row inside the worksheet has no effect on the selection, there are no indications related to this. • Named Selections require valid scoping. If the application detects a criterion that is not properly scoped, it becomes highlighted in yellow to alert users of a possible problem. A highlighted criterion does not effect on the overall state of the object.

Worksheet Entries and Operation A sample worksheet is illustrated below.

Once a row has been placed in the Worksheet, the right-click context menu activates options to Insert additional rows, Modify rows, and/or Delete rows.

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Named Selections Criteria of the Worksheet is defined by making selections in the drop-down menus of the columns for each row. Certain values are read-only or they are only available as the result of other criterion being specified. The content of each Worksheet column is described below. Action column: • Add: Adds the information defined in the current row to information in the previous row, provided the item defined in the Entity Type column is the same for both rows. • Remove: Removes the information defined in the current row from information in the previous row, provided the geometry defined in the Entity Type column is the same for both rows. • Filter: Establishes a subset of the information defined in the previous row. • Invert: Selects all items of the same Entity Type that are not currently in the named selection. • Convert To: Changes the geometric Entity Type selected in the previous row. The change is in either direction with respect to the topology (for example, vertices can be converted “up” to edges, or bodies can be converted “down” to faces). When going up in dimensionality, the higher level topology is selected if you select any of the lower level topology (for example, a face will be selected if any of its edges are selected). You can also convert from a geometry selection (bodies, edges, faces, vertices) to mesh nodes. The nodes that exist on the geometry (that is, the nodes on a face/edge/vertex or nodes on and within a body) will be selected. In addition, node-based Named Selections can be converted to elements and element-based Named Selections can be converted to nodes using this action.

Note The conversion from geometry selection to mesh nodes is analogous to using Mechanical APDL commands NSLK, NSLL, NSLA, and NSLV. The conversion from elements to mesh nodes uses NSLE and conversion from mesh nodes to elements uses ESLN.

Entity Type column: • Body • Face • Edge • Vertex • Mesh Node • Mesh Element Criterion column: • Size - available when Entity Type = Body, Face, or Edge. • Type - available when Entity Type = Body, Face, Edge, or Mesh Node, or Mesh Element. • Location X Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Specifying Geometry • Location Y • Location Z • Face Connections - available when Entity Type = Edge. • Radius - available when Entity Type = Face or Edge. Applies to faces that are cylindrical and edges that are circular. • Distance

Note For the Distance Criterion, the calculation of the centroid is not supported for Line Bodies.

• Named Selection • Material - available when Entity Type = Body. • Node ID - Available when Entity Type is Mesh Node. • For Entity Type = Mesh Element. – Element ID – Volume – Area – Element Quality – Aspect Ratio – Jacobian Ratio – Warping Factor – Parallel Deviation – Skewness – Orthogonal Quality You may wish to refer to the Mesh Metric section of the Meshing User's Guide for more information about these Criterion options. Operator column: • Equal • Not Equal • Less Than • Less Than or Equal 436

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Named Selections • Greater Than • Greater Than or Equal • Range includes Lower Bound and Upper Bound numerical values that you enter. • Smallest • Largest Units column: read-only display of the current units for Criterion = Size or Location X, Y, or Z. Value column: • For Criterion = Size, enter positive numerical value. • For Criterion = Location X, Y, or Z, enter numerical value.

Note Selection location is at the centroids of edges, faces, bodies, and elements.

• For Entity Type = Body and Criterion = Type: – Solid – Surface – Line • For Entity Type = Face and Criterion = Type: – Plane – Cylinder – Cone – Torus – Sphere – Spline – Faceted • For Entity Type = Edge Criterion = Type: – Line – Circle – Spline – Faceted Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Specifying Geometry • For Entity Type = Mesh Node and Criterion = Type: – Corner – Midside • For Entity Type = Mesh Element and Criterion = Type: – Tet10 – Tet4 – Hex20 – Hex8 – Wed15 – Wed6 – Pyr13 – Pyr5 – Tri6 – Tri3 – Quad8 – Quad4 – High Order Beam – Low Order Beam • For Entity Type = Edge and Criterion = Face Connections, enter the number of shared edge connections. For example, enter Value = 0 for edges not shared by any faces, enter Value = 1 for edges shared by one face, and so on. • For Criterion = Named Selection, you can include a previously-defined named selection from the Value field. Only the named selections that appear in the tree before the current named selection are listed in Value. For example, if you have defined two named selections prior to the current named selection and two named selections after, only the two prior to the current named selection are shown under Value. When you define a named selection to include an existing named selection, you should use the Generate Named Selections RMB option from the Named Selections folder object in the tree to make sure that all of the latest changes to all named selections are captured. Named selections are generated in the order that they are listed in the tree and as a result, when you click the Generate button in the Worksheet, only the associated named selection is updated. Any other Named Selection that may have been changed is not updated. The Generate Named Selections feature better ensures that all child objects of the Named Selection folder are updated. For Criterion = Material, select the desired material from the drop-down list. See the Material Assignment topic for more information.

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Named Selections • For Criterion = Distance, enter a positive numerical value from the origin of the selected coordinate system. Lower Bound column: enter numerical value. Upper Bound column: enter numerical value. Coordinate System column: • Global Coordinate System • Any defined local coordinate systems

Adjusting Tolerance Settings for Named Selections by Worksheet Criteria Tolerance settings are used when the Operator criterion is defined as an "equal" comparison. Tolerances are not used when doing greater than or less than operations. Tolerance values apply to the entire worksheet. If you wish to adjust the tolerance settings for worksheet criteria, use the Tolerance settings in the chosen Named Selection’s Details view. By default, the Zero Tolerance property is set to 1.e-008 and the Relative Tolerance value is 1.e-003. As a result of the significant digit display, the value used for calculations and the display value may appear to be different. The Zero Tolerance property’s value is past the number of significant digits that Mechanical shows by default. The application’s default setting for significant digits is 5 (the range is 3 to 10). This setting affects only the numbers that are displayed, any calculation or comparison uses the actual values when processing. In addition, it is important to note that most values (including selection values seen in the status bar and the Selection Information window) in Mechanical display in a significant digit format. See the Appearance option in the Setting ANSYS Workbench section of the Help for information about changing default display settings. Setting the tolerance values manually can also be useful in meshing, when small variances are present in node locations and the default relative tolerance of .001 (.1%) can be either too small (not enough nodes selected) or too big (too many nodes selected). 1.

In the Details view, set Tolerance Type to Manual.

2.

Specify either a Zero Tolerance or a Relative Tolerance. Tolerance values are dimensionless. Relative tolerance is a multiplying factor applied to the specified worksheet value. For example, if you want a tolerance of 1%, enter .01 in the Relative Tolerance field. All comparisons are done in the CAD unit system.

Criteria Named Selections Based on Selected Geometry You may have the need to create Named Selections that use criteria but are based on pre-selected geometry. For example, the criteria may be to pick every face that shares both the same X location and the same size as the selected face. For these situations, you can first select the geometry, then, instead of configuring the Worksheet directly, you can use the following more direct procedure to define the criteria for the Named Selection. 1. After selecting geometry, choose Create Named Selection (left button on the Named Selection Toolbar (p. 69) or right-click context menu choice). 2. In the Selection Name dialog box that appears, you can enter a name for the particular Named Selection or accept Selection as the default name. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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a. To define the Named Selection based only on the selected geometry without defining any criteria, choose Apply selected geometry and click OK. b. To define the Named Selection based on criteria related to the selected geometry: i.

Choose Apply geometry items of same, then check one or more applicable criteria items and click OK. These items are sensitive to the selected geometry (for example, if a vertex is selected, there are no Size or Type entries).

ii. Choosing the above option activates the Apply to Corresponding Mesh Nodes field. Checking this field automatically adds a Covert To (see Help above) row to the Worksheet that coverts the geometry to mesh nodes.

Note This option requires that you generate the mesh.

Once the above steps are completed, the Named Selection is automatically generated and listed as a Selection object (default name) under the Named Selections folder. If you specified criteria and highlight the Selection object, the associated Worksheet is populated automatically with the information you entered in the Selection Name dialog box. To illustrate the steps presented above: 1. Select a face. 2. Choose Create Named Selection. 3. Choose Apply geometry items of same. 4. Check Size and Location X, then choose OK. 440

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Named Selections The Worksheet associated with the new Named Selection would be populated automatically with the following information: First Row • Action = Add • Entity Type = Face • Criterion = Size • Operator = Equal Second Row • Action = Filter • Entity Type = Face • Criterion = Location X • Operator = Equal

Promoting Scoped Objects to a Named Selection In addition to creating Named Selections, you can also use the promotion feature to create a named selection from an existing object that is scoped to geometry or mesh. Objects that support the promotion feature include: • Remote Points • Contact Regions • Springs • Joints • Boundary Conditions • Results and Custom Results All of these objects have one thing in common when using the promotion feature, they are first scoped to geometry or mesh. This is the specification basis for the promoted Named Selections. Each promoted Named Selection inherits the geometry or mesh scoping of the object used. In addition, the Scoping Method property automatically updates to Named Selection and specifies the corresponding scoping.

Note • This action changes the scoping of the corresponding object and may, as a result, cause upto-date states to become obsolete. For example, promoting a Fixed Support from a completed solution would cause the solution to become obsolete and require it to be re-solved. • In order to promote objects scoped to the mesh, you need to make sure that the Show Mesh feature (on the Graphics Options Toolbar) is active.

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Specifying Geometry By highlighting one of the above objects and right-clicking, such as the Contact Region example illustrated below, the context menu provides the option Promote to Named Selection. Once selected, the feature automatically adds a Named Selections folder to the tree that includes two new Named Selections based on the existing name of the contact object as well as its geometry scoping, Contact and Target. You can promote an object to a Named Selection only once. Deleting the corresponding Named Selection makes the option available again. However, deleting the Named Selection also invalidates the corresponding source object, such as the Contact Region shown in the example below. As a result, you must re-scope the source object to geometry or mesh for the feature to be available. A Contact Region example is slightly different in that it has Contact and Target scoping and that this feature creates two Named Selections. Springs and Joints also create two Named Selections if they are defined as BodyBody. The other object types create one Named Selection. Also note that result objects can be promoted before or after the solution process.

Displaying Named Selections You can use geometry entity Named Selections to inspect only a portion of the total mesh. Although this feature is available regardless of mesh size, it is most beneficial when working with a large mesh (greater than 5 - 10 million nodes). After you have designated a Named Selection group, you can use any of the following features to assist you in this task:

Showing the Mesh By setting the Plot Elements Attached to Named Selections option in the Annotation Preferences, you can view the elements for all items in the Named Selection group. For node-based Named Selections,

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Named Selections this option shows the full elements, while for face or body Named Selections, this option shows just the element faces.

Note This option does not affect Line Bodies, and you must have the Show Mesh button toggled off to view the elements in the Named Selection. An example is shown below of a node-based Named Selection.

Showing Annotations As illustrated below, selecting the Named Selection folder displays all of the user-defined Named Selection annotations in the Graphics pane. This display characteristic can be turned On or Off using the Show Annotation category in the Named Selections Details view. Selecting an individual Named Selection displays the annotation specific to that Named Selection in the Graphics pane.

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Specifying Geometry You can also toggle the visibility of mesh node annotations and numbers in the annotation preferences. For more information, see Specifying Annotation Preferences (p. 119).

Displaying Individual Named Selections in Different Colors By default, Named Selections are shown in red. You can use the Random Colors button in the Graphics Options toolbar to display each named selection with a random color at each redraw.

Setting Visibility By setting the Visible object property in the Details view of an individual Named Selection object to No, the Named Selection can be made invisible, meaning it will not be drawn and, more importantly, not taken into consideration for picking or selection. This should allow easier inspection inside complicated models having many layers of faces where the inside faces are hardly accessible from the outside. You can define Named Selections and make them invisible as you progress from outside to inside, similar to removing multiple shells around a core. The example shown below displays the Named Selection 3 Faces with the Visible property set to No.

Displaying an Enhanced View of Meshed Items Display your model in Wireframe mode by selecting the Wireframe button on the Graphics Options Toolbar or by selecting View> Wireframe. Then, open the Annotation Preferences dialog box by selecting 444

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Named Selections View>Annotation Preferences. Check the Plot Elements Attached to Named Selections option. This feature displays the meshed entities of your Named Selection only, as illustrated below.

Notes • The Visible object property is the same as the Hide Face(s) option in the right mouse button context menu. These options will hide only the specified Named Selection. This behavior differs from that of the Hide Bodies in Group and Suppress Bodies in Group options, which hide or suppress the full body containing a given Named Selection. • When a Named Selection's Visible setting is set to No: – Only the faces from that Named Selection are not drawn; the edges are always drawn. – The Named Selection will not appear in any drawing of the geometry (regardless of which object is selected in the tree). Unless... – The Named Selection is displayed as meshed, it displays the mesh, but only if you have the Named Selection object or the Named Selections folder object is selected in the tree. This behavior is the same as the behavior of the red annotation in the Geometry window for Named Selections (that is, the annotation appears only when the current selected object is the specific Named Selection object or the Named Selections folder object). • After at least one Named Selection is hidden, normally you can see the inside of a body, so displaying both sides of each face is enabled (otherwise displaying just the exterior side of each face is enough). But if a selection is made, the selected face is always displayed according to the option in Tools> Options> Mechanical> Graphics> Single Side (can be one side or both sides). • If the Wireframe display option is used and Show Mesh is Yes, any face selected is displayed according to the option in Tools> Options> Mechanical> Graphics> Single Side (can be one side or both sides).

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Using Named Selections This section describes the features for managing and employing Named Selections, and includes: Using Named Selections via the Toolbar Scoping Analysis Objects to Named Selections Including Named Selections in Program Controlled Inflation Importing Named Selections Exporting Named Selections

Using Named Selections via the Toolbar The Named Selection toolbar allows you to select and modify user-defined named selections. You can turn it on or off by selecting View> Toolbars> Named Selections. To use a Named Selection toolbar: 1. Select a named selection from the drop-down list of available Named Selections. This list matches the named selections contained beneath the Named Selections folder object. 2. Choose from the following options provided by toolbar: Control

Description

Selection drop-down menu

Controls selection options on items that are part of the group whose name appears in the Named Selection display. Available options are:

(or in context menu from right clicking the mouse button on individual Named Selection object)

• Select Items in Group: selects only those items in the named group. • Add to Current Selection: Picks the scoped items defined by the Named Selection that you have highlighted and adds those items to the item or items that you have selected in the geometry window. This option is grayed out if the selections do not correspond, such as selecting trying to add a faces to vertices. • Remove from Current Selection: Removes the selection of items in the named group from other items that are already selected. Selected items that are not part of the group remain selected. This option is grayed out if the entity in the Named Selection does not match the entity of the other selected items. • Create Nodal Named Selection: Automatically converts the geometry specified by the Named Selection to mesh nodes. A corresponding Covert To row is added to the Worksheet

Note Choosing any of these options affects only the current selections in the Geometry view, These options have no effect on what is included in the Named Selection itself. Visibility dropdown menu

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Controls display options on bodies that are part of the group whose name appears in the Named Selection display. Available options are: Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

Named Selections Control

Description • Hide Bodies in Group: Turns off display of bodies in the named group (toggles with next item). Other bodies that are not part of the group are unaffected. • Show Bodies in Group: Turns on display of bodies in the named group (toggles with previous item). Other bodies that are not part of the group are unaffected. • Show Only Bodies in Group: Displays only items in the named group. Other items that are not part of the group are not displayed. You can also hide or show bodies associated with a Named Selection by right-clicking the Named Selections object and choosing Hide Bodies in Group or Show Bodies in Group from the context menu. You can hide only the Named Selection by right-clicking on the Named Selections object and choosing Hide Face(s).

Suppression drop-down menu

Controls options on items that affect if bodies of the group whose name appears in the Named Selection display are to be suppressed, meaning that, not only are they not displayed, but they are also removed from any treatment such as loading or solution. Available options are: • Suppress Bodies in Group: Suppresses bodies in the named group (toggles with next item). Other bodies that are not part of the group are unaffected. • Unsuppress Bodies in Group: Unsuppresses bodies in the named group (toggles with previous item). Other bodies that are not part of the group are unaffected. • Unsuppress Only Bodies in Group: Unsuppresses only bodies in the named group. Other bodies that are not part of the group are suppressed. You can also suppress or unsuppress bodies associated with a Named Selection by right-clicking the particular Named Selections object and choosing Suppress Bodies In Group or Unsuppress Bodies In Group from the context menu. The Suppress Bodies In Group and Unsuppress Bodies In Group options are also available if you select multiple Named Selection items under a Named Selections object. The options will not be available if your multiple selection involves invalid conditions (for example, if you want to suppress multiple items you have selected and one is already suppressed, the Suppress Bodies In Group option will not be available from the context menu.

The status bar shows the selected group area only when the areas are selected. The group listed in the toolbar and in the Details View (p. 11) provides statistics that can be altered.

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Specifying Geometry

Scoping Analysis Objects to Named Selections Many objects can be scoped to Named Selections. Some examples are contact regions, mesh controls, loads, supports, and results. To scope an object to a Named Selection: 1. Insert or select the object in the tree. 2. Under the Details view, in the Scoping Method drop-down menu, choose Named Selection. 3. In the Named Selection drop-down menu, choose the particular name. Notes on scoping items to a Named Selection: • Only Named Selections valid for the given analysis object are displayed in the Named Selection dropdown menu. If there are no valid Named Selections, the drop-down menu is empty. • No two Named Selections branches can have the same name. It is recommended that you use unique and intuitive names for the Named Selections. • Named Selection modifications update scoped objects accordingly. • Deleting a Named Selection causes the scoped object to become underdefined. • If all the components in a Named Selection cannot be applied to the item, the Named Selection is not valid for that object. This includes components in the Named Selection that may be suppressed. For example, in the case of a bolt pretension load scoped to cylindrical faces, only 1 cylinder can be selected for its geometry. If you have a Named Selection with two cylinders, one of which is suppressed, that particular Named Selection is still not valid for the bolt pretension load.

Including Named Selections in Program Controlled Inflation By default, faces in Named Selections are not selected to be inflation boundaries when the Use Automatic Inflation control is set to Program Controlled. However, you can select specific Named Selections to be included in Program Controlled inflation. To do so: 1. Create a Named Selection. 2. Click the desired Named Selection in the tree and then in the Details view, set the Program Controlled Inflation option to Include. 3. In the mesh controls, set the Use Automatic Inflation control to Program Controlled. As a result, the Named Selection you chose in step 2 is selected to be an inflation boundary, along with any other faces that would have been selected by default.

Importing Named Selections You can import geometric entity Named Selections that you defined in a CAD system or in DesignModeler. A practical use in this case is if you want the entities of the Named Selection group to be selected for the application of loads or boundary conditions. To import a Named Selection from a CAD system or from DesignModeler:

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Named Selections 1. In the Geometry preferences, located in the Workbench Properties of the Geometry cell in the Project Schematic, check Named Selections and complete the Named Selection Key; or, in the Geometry Details view under Preferences, set Named Selection Processing to Yes and complete the Named Selection Prefixes field (refer to these entries under Geometry Preferences for more details). 2. A Named Selections branch object is added to the Mechanical application tree. In the Named Selection Toolbar, the name of the selection appears as a selectable item in the Named Selection display (located to the right of the Create Selection Group button), and as an annotation on the graphic items that make up the group.

Exporting Named Selections You can export the Named Selection that you create using the Graphics Viewer and Worksheet, and save the contents to a text or Microsoft Excel file. To export the Named Selection object: 1. Right-click on the desired Named Selection object and select Export. 2. Name and save the file. The text or Microsoft Excel file you export includes a list of generated node ids, by default. You can also include the location information of the generated node ids in the exported file. To include node id location information in the exported file: 1.

Click Tools > Options

2.

Expand the Mechanical folder, and then click Export

3.

Under Export, click the Include Node Location drop-down list, and then select Yes.

Note • The Named Selection Export feature is available only for node-based and element-based Named Selection objects. • Node Numbers are always shown in the exported text or Microsoft Excel file irrespective of setting for Include Node Numbers in Tools > Options > Export.

Displaying Interior Mesh Faces There are special instances when a Named Selection is an interior “back-facing face”. This is a unique case that occurs when the external faces of the geometry are hidden allowing interior faces to become visible. To display the faces of the mesh, the Named Selections object must be highlighted in the tree and the Plot Elements Attached to Named Selections option in the Annotation Preferences must be selected. Then, to correct the display, use the Draw Face Mode options available under View>Graphics Options, which include:

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Specifying Geometry • Auto Face Draw (default) - turning back-face culling on or off is program controlled. Using Section Planes is an example of when the application would turn this feature off. • Draw Front Faces - face culling is forced to stay on. Back-facing faces will not be drawn in any case, even if using Section Planes. • Draw Both Faces - back-face culling is turned off. Both front-facing and back-facing faces are drawn. Incorrect Display

Correct Display using Draw Face Mode

Converting Named Selection Groups to Mechanical APDL Application Components When you write a Mechanical APDL application input file that includes a Named Selection group, the group is transferred to the Mechanical APDL application as a component provided the name contains only standard English letters, numbers, and underscores. The Named Selection will be available in the input file as a Mechanical APDL component for use in a Commands object. Geometry scoping to bodies will result in an element-based component. All other scoping types will result in a nodal component. The following actions occur automatically to the group name in the Mechanical application to form the resulting component name in the Mechanical APDL application: • A name exceeding 32 characters is truncated. • A name that begins with a number is renamed to include “C_” before the number. • Spaces between characters in a name are replaced with underscores. Example: The Named Selection group in the Mechanical application called 1 Edge appears as component C_1_Edge in the Mechanical APDL application input file.

Note Named selections starting with ALL, STAT, or DEFA will not be sent to the Mechanical APDL application.

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Mesh Numbering

Mesh Numbering The Mesh Numbering feature allows you to renumber the node and element numbers of a generated meshed model consisting of flexible parts. The feature is useful when exchanging or assembling models and could isolate the impact of using special elements such as superelements. The Mesh Numbering feature is available for all analysis systems except Rigid Dynamics analyses. Because this feature changes the numbering of the model’s nodes, all node-based scoping is lost when mesh numbering is performed, either in a suppressed or unsuppressed state. If this situation is encountered, a warning message allows you to stop the numbering operation before the node-based scoping is removed. You can prevent the loss of any node-based scoping by using criteria-based Named Selections, or by scoping an object to nodes after mesh renumbering has taken place. Criteria-based Named Selections scoped to nodes are supported in combination with the Mesh Numbering object as long as you have the Generate on Remesh property set to Yes. To activate Node Number Compression: By default node numbers will not be compressed to eliminate gaps in the numbering that can occur from events such as remeshing or suppression of meshed parts. This allows maximum reuse of mesh based Named Selections but can result in node numbers that are higher than required. Node number compression can be turned on by setting Compress Numbers to Yes. If compression is turned on, the compression will occur before any other numbering controls are applied. To activate Mesh Numbering: 1. Insert a Mesh Numbering folder by highlighting the Model folder, then: a. Selecting the Mesh Numbering toolbar button. Or... b. Right-clicking on the Model folder and choosing Insert> Mesh Numbering. Or... c. Right-clicking in the Geometry window and choosing Insert> Mesh Numbering. 2. In the Details view, set Node Offset or Element Offset values for the entire assembly, as needed. For example, specifying a Node Offset of 2 means that the node numbering for the assembly will start at 2.

Note The Node Offset value cannot exceed a value that results in a node number having a magnitude greater than one (1) billion. Mesh numbering of this magnitude requires considerable processing power.

3. Insert a Numbering Control object by highlighting the Mesh Numbering folder (or other Numbering Control object), then:

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Specifying Geometry a. Selecting the Numbering Control toolbar button. Or... b. Right-clicking on the Mesh Numbering folder (or other Numbering Control object) and choosing Insert> Numbering Control. Or... c. Right-clicking in the Geometry window and choosing Insert> Numbering Control. 4. Specify a part, a vertex, or a Remote Point in the model whose node or element numbers in the corresponding mesh are to be renumbered. a. To specify a part: i.

Select the part.

ii. In the Details view, set Scoping Method to Geometry Selection, click the Geometry field and click Apply. iii. Enter numbers in the Begin Node Number and/or Begin Element Number fields. Also, if needed, change the End Node Number and End Element Number from their default values. b. To specify a vertex: i.

Select the vertex.

ii. In the Details view, set Scoping Method to Geometry Selection, click the Geometry field and click Apply. iii. Enter the Node Number. c. To specify a Remote Point that has already been defined: i.

In the Details view, set Scoping Method to Remote Point, click the Remote Points field and choose the specific Remote Point in the drop down menu.

ii. Enter the Node Number. 5. Right-click the Mesh Numbering folder, or a Numbering Control object, and choose Renumber Mesh. If the model is not meshed, it will first generate a mesh and then perform mesh numbering. The nodes and elements are numbered based on the values that you specified.

Note During the mesh numbering process, the user interface enters a waiting state, meaning you cannot perform any actions such as clicking objects in the tree. In addition, you cannot cancel the process once it is started and must wait for its completion. However, a progress dialog box appears to report status during the operation.

Mesh Numbering Characteristics • The Mesh Numbering feature is available in both the Mechanical application and the Meshing applications. 452

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Path (Construction Geometry) • The Node Offset value cannot exceed a value that results in a node number having a magnitude greater than one (1) billion. Mesh numbering of this magnitude requires considerable processing power. • Geometry selection is part-based, not body-based. • Selecting Update at the Model level in the Project Schematic updates the mesh renumbering. • The Solve is aborted if mesh renumbering fails. • Whenever a control is changed, added, or removed, the mesh renumbering states are changed for all controls where mesh numbering is needed. • When exporting mesh information to Fluent, Polyflow, CGNS, or ICEM CFD format, the last status is retained at the time of export. If renumbering has been performed, the mesh is exported with nodes and elements renumbered. If not, the original mesh numbering is used. • Mesh renumbering of a Point Mass is not supported. • The Convergence object is not supported with Mesh Numbering folder.

Note Be cautious when deleting the Mesh Numbering folder. Deleting this folder leaves the mesh in the numbered state that you specified. There is no way to know that the existing mesh has been renumbered.

Mesh Numbering Suppression Characteristics For Mesh Numbering, the suppression feature operates differently. Rather than excluding the object when the Mesh Numbering object is suppressed, the mesh numbering instead returns to the original numbering. That is, it resets and updates the input deck’s contents. This change can affect analysis operations. As a result, restrictions have been implemented, and Mechanical no longer supports suppression of the Mesh Numbering object. For legacy (v14.5 and earlier) files, an error is generated in the Message Window if suppressed Mesh Numbering objects are present. You can continue your analysis by manually changing the Suppressed property setting to No, but the change is then permanent; the application will not allow you to return this setting to Yes.

Path (Construction Geometry) A path is categorized as a form of construction geometry and is represented as a spatial curve to which you can scope path results. The results are evaluated at discrete points along this curve. A path can be defined in two principal ways: • By start point and end point. These points can be specified directly or can be calculated from the entry and exit point (intersections) of the positive X-axis of a coordinate system through a mesh. The path may be a straight line segment or a curve depending on the type of coordinate system (Cartesian or Cylindrical). You can control

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Specifying Geometry the discretization by specifying the number of sampling points, and these will be evenly distributed along the path up to a limit of 200.

Note Paths defined in this manner will only be mapped onto solid or surface bodies. If you wish to apply a path to a line body you must define the path by an edge (as described below).

• By an edge. The discretization will include all nodes in the mesh underlying the edge. Multiple edges may be used but they must be continuous. For each result scoped to a Path, the Graph Controls category provides an option to display the result in the Graph on X-axis, as a function of Time or with S, the length of the path. Note that Path results have the following restrictions: They are calculated on solids and surfaces but not on lines. They can be collected into charts as long as all of the other objects selected for the chart have the same X-axis (Time or S). You can define a path in the geometry by specifying two points, an edge, or an axis. Before you define a path, you must first add the Path object from the Construction Geometry context toolbar. You can then define the path using any of the three methods presented below.

Defining a Path using Two Points Using this method you define the path by specifying two points in any of the following ways: To define the path using the Coordinate toolbar button: 1. In the Details view, select Two Points in the Path Type list. 2. Under Start, choose Click to Change in the Location row . 3. Depress the Coordinate toolbar button. As you move the cursor across the model, the coordinates display and update as you reposition the cursor.

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Path (Construction Geometry) 4. Click at the desired start location for the path. A small cross hair appears at this location. You can click again to change the cross hair location. 5. Click Apply. A “1” symbol displays at the start location. Also, the coordinates of the point display in the Details view. You can change the location by repositioning the cursor, clicking at the new location, and then clicking Click to Change and Apply, or by editing the coordinates in the Details view. 6. Repeat steps 2 through 5 to define the end point of the path under End in the Details view. A “2” symbol displays at the end location. 7. Enter the Number of Sampling Points. To define the path using coordinates: 1.

In the Details view, select Two Points in the Path Type list.

2.

Under Start, enter the X, Y, and Z coordinates for the starting point of the path.

3.

Under End, enter the X, Y, and Z coordinates for the ending point of the path.

4.

Enter the Number of Sampling Points.

To define a Path using vertices, edges, faces, or nodes: 1.

In the Details view, select Two Points in the Path Type list.

2.

Select one or more vertices or nodes, a single edge, or a face where you want to start the path, and then click Apply under Start, Location. An average location is calculated for multiple vertex or node selections.

3.

Select the vertices, nodes, face, or the edge where you want to end the path, and then click Apply under End, Location.

4.

Enter the Number of Sampling Points.

Note The start and end points need not both be specified using the same procedure of the three presented above. For example, if you specify the start point using the Coordinate toolbar button, you can specify the end point by entering coordinates or by using a vertex, edge, or face. Any combination of the three procedures can be used to specify the points.

Snap to Mesh Nodes When solving linearized stresses, the path you define by two points must be contained within the finite element mesh to avoid an error. Because the two points can be derived from the tessellation of the geometric model, the points may be contained within the geometry but may not be contained within the mesh. This is especially true for curved geometry faces. After defining the two points using the Coordinate toolbar button method (see above), you can ensure that the path is contained within the mesh by using the Snap to mesh nodes feature. To use the feature, set Show Mesh to Yes in the Details view of the Construction Geometry object in order to see the location of the nodes in the mesh. Then, right click on the Path object and select Snap to mesh nodes from the context menu. This action alters the path, as necessary, such that both the start point and end point of the path snap to the closest node in the mesh. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Specifying Geometry The Snap to mesh nodes feature avoids the error and allows the solve to continue provided the path you define does not traverse through any discontinuities in the model, such as a hole. For these cases, even though the Snap to mesh nodes feature alters the path endpoints to coincide with the nearest nodes in the mesh, the linearized stress result still fails because the path is defined through the discontinuity. The following pictures illustrate this feature. Attempt to solve for linearized stress. Path defined within geometric model:

Corresponding mesh used for geometric model, obtained by setting Show Mesh to Yes:

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Path (Construction Geometry)

Path contained within mesh after choosing Snap to mesh nodes. Solution completes:

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Specifying Geometry

Note If the model is re-meshed after choosing Snap to mesh nodes, the feature is not automatically applied to the newly meshed model. You must choose Snap to mesh nodes again to alter the path start and end points to the new mesh.

Defining a Path using an Edge This method helps you define a path by selecting an edge. To define a path: 1.

In the Details view, select Edge in the Path Type list.

2.

Select a geometry edge, and then click Apply under Scope.

Defining a Path from Results Scoped to Edges In order to help better quantify the variation of a result along a set of edges, path results are available. For a result that is scoped to an edge or multiple contiguous edges, you can convert the scoping to the equivalent Path, by: 1.

Selecting the result object that is scoped to an edge or contiguous edges.

2.

Display the context menu by right-clicking the mouse, and the select Convert To Path Result.

A Path is automatically created and a corresponding Path object is displayed in the tree with a Path Type of Edge.

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Surface (Construction Geometry)

Defining a Path using X-axis Intersection Depending on the coordinate system you select, Workbench creates a Path from the coordinate system origin to the point where the X-axis of the selected coordinate system intersects a geometry boundary. Workbench computes intersections of the axis with the mesh and displays more precise locations for path endpoints for the path results. The endpoints for the path are not modified, and remain as the intersections with the geometry. The first compact segment of the path inside a single body is included in the path definition. 1.

In the Details view, select X Axis Intersection in the Path Type list.

2.

Select the coordinate system you want to use to define the x-axis.

3.

Enter the Number of Sampling Points.

Defining a Path from Probe Labels While reviewing results, you can define a path automatically from two probe labels. To define the path: 1.

Create two probe annotations by choosing the Probe button from the Result Context Toolbar (p. 59).

2.

Choose the Label button from the Graphics Toolbar (p. 50) and select the two probe annotations. (Hold the Ctrl key to select both probe annotations.)

3.

Right-click in the Geometry window and choose Create Path From Probe Labels from the context menu.

4.

A path is automatically created between the probe annotations. A corresponding Path object is displayed in the tree with a Path Type of Two Points.

Exporting Path Data You can export coordinate data for a defined path by clicking the right mouse button on a Path object and choosing Export from the context menu.

Surface (Construction Geometry) A surface is categorized as a form of construction geometry and is represented as a section plane to which you can scope surface results or reaction probes. To define a surface: 1. Highlight the Model object and click the Construction Geometry toolbar button to produce a Construction Geometry object. 2. Highlight the Construction Geometry object and click the Surface toolbar button to produce a Surface object. 3. Define a coordinate system whose X-Y plane will be used as a cutting plane, as follows: a. Create a local coordinate system.

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Specifying Geometry b. Define the origin of the local coordinate system.

Note With respect to the facets of the surface: • For a Cartesian coordinate system, the surface is the intersection of the model with the X-Y plane of the coordinate system. • For a cylindrical coordinate system, the surface is the intersection of the model with the cylinder whose axis is the Z axis of the coordinate system. In this case, you must specify the radius in the Details view of the Surface object.

Tip For an existing coordinate system, you can define a Surface Construction Geometry object by selecting the desired coordinate system object, right-clicking, and selecting Create Construction Surface. This feature allows you to define the coordinate system first.

Remote Point You use a Remote Point as a scoping mechanism for remote boundary conditions. Remote points are a way of abstracting a connection to a solid model, be it a vertex, edge, face, body, or node, to a point in space (specified by Location). The solver uses multipoint constraint (MPC) equations to make these connections. Remote Points are akin to the various remote loads available in the Mechanical application. Remote boundary conditions create remote points in space behind the scenes, or, internally, whereas the Remote Point objects define a specific point in space only. As a result, the external Remote Point can be associated to a portion of geometry that can have multiple boundary conditions scoped to it. This single remote association avoids overconstraint conditions that can occur when multiple remote loads are scoped to the same geometry. The overconstraint occurs because multiple underlying contact elements are used for the individual remote loads when applied as usual to the geometry. When the multiple remote loads are applied to a single remote point, scoped to the geometry, the possibility of overconstraint is greatly reduced. Remote Points are a powerful tool for working with and controlling the Degrees of Freedom (DOF) of a body. Remote Points provide a property, DOF Selection, which gives you a finer control over the active DOF's used to connect the Remote Point location to the body. Furthermore, Remote Points can be can be used independently, without being scoped to a boundary condition. Remote Point create MPC equations and therefore can be used to model phenomena, such as coupling a set of nodes so that they have the same DOF solution. Another capability of Remote Points is that they are also a scoping mechanism for the Constraint Equation object. The equation relates the degrees of freedom (DOF) of one or more remote points A Remote Point or multiple remote points work in tandem with the boundary conditions listed below. • Point Mass

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Remote Point • Thermal Point Mass • Joints • Spring • Bearing • Beam Connection • Remote Displacement • Remote Force • Moment These objects acquire data from remote points and eliminate the need to define the objects individually. You can scope one or more of the above objects to a defined Remote Point. This provides a central object to which you can make updates that will affect the scoping of multiple objects.

Note Following are important points to keep in mind when using Remote Points: • A Remote Point can reference only one Remote Force and one Moment. If you scope a Remote Point to multiple remote forces or moments, duplicate specifications are ignored and a warning message is generated. • A Remote Point with Deformable behavior should not be used on surfaces that are modeled with symmetry boundary conditions. The internally generated weight factors only account for the modeled geometry. Therefore, remote points with deformable behavior should only be used on the “full” geometry.

For additional MAPDL specific information, see the Multipoint Constraints and Assemblies section as well as KEYOPT(2) in the Mechanical APDL Contact Technology Guide. The following sections describe how to create and define a Remote Point as well as the characteristics and limitations associated with this scoping tool. Specify a Remote Point Geometry Behaviors and Support Specifications Remote Point Features

Specify a Remote Point To insert a Remote Point, select the Model object in the tree and then either select the Remote Point button from the Model Context Toolbar or right-click the mouse and select Insert>Remote Point. You then scope the Remote Point to a face or faces, edge or edges, vertex or vertices, or a node or nodes.

Note To select a node or nodes, you first need to generate the mesh.

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Specifying Geometry MAPDL Reference When you scope your Remote Point to a single node or multiple nodes, a point-to-surface contact algorithm is used (using contact element CONTA175). This process can produce slightly different result at the area of application compared to face scoping of the same topology. Geometry scoping to 3D faces and 2D edges uses a constant traction contact application (contact elements CONTA171 through CONTA174).

Note Be very careful when you scope remote points to nodes if the nodes are collinear. A rigid Formulation avoids issues when you scope to Surface or Line bodies. However for solids, you should not scope collinear nodes for any Formulation. Remote Point definable properties are illustrated and described below: • Scoping Method: Geometry (default) or Named Selection. • Geometry or Named Selection (geometry or node-based) selection. • Coordinate System: the Coordinate System based on the original location of the remote point. This property does not change if you modify the remote point’s position with the Location property. • X Coordinate: the distance from the coordinate system origin on the x axis. • Y Coordinate: the distance from the coordinate system origin on the y axis. • Z Coordinate: the distance from the coordinate system origin on the z axis. • Location: the location in space of the remote point. This property allows you to manually modify the remote point’s original position. Changing the Location does not establish a new coordinate system (that is not reflected by the above Coordinate System property) and replots the x, y, and z coordinate locations. • Behavior. This property defines the contact formulations. Options include Deformable, Rigid, or Coupled. • Pinball Region: value entry. • DOF Selection: Program Controlled (default) or set as Manual. This offers an opportunity for better control of which DOF’s will activate for corresponding constraint equations.

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Remote Point The Details view of each of the above objects contains a Scoping Method setting that can be set to Remote Point, once a Remote Point is defined, as illustrated below for the details of a Remote Force. Once you scope the object with a Remote Point and define which remote point (Remote Point Front Edge or Remote Point Rear Face) if more than one exists, all of the inputs from that remote point become read-only for the object and use the remote point's data. Scope to Remote Point

Choose Appropriate Remote Point

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Specifying Geometry

As illustrated in the above example, after you have scoped the Remote Force to a Remote Point, additional data may be required, such as Magnitude.

Geometry Behaviors and Support Specifications The Behavior option dictates the behavior of the attached geometry. You can specify the Behavior of the scoped geometry for a remote boundary condition in the Details view as either Rigid, Deformable, or Coupled. • Deformable - The geometry is free to deform. This is a general purpose option used when applying boundary conditions such as a force or mass through ”abstract” entities not explicitly represented as geometry inside Mechanical. This formulation is similar to the MAPDL constraint defined by the RBE3 command. • Rigid - The geometry will not deform (maintains the initial shape). This option is useful when the "abstracted" object significantly stiffens the model at the attachment point. Note that thermal expansion effects cause artificially high stresses because the geometry cannot deform where the load is applied. This formulation is similar to the MAPDL constraint defined by the CERIG command. • Coupled - The geometry has the same DOF solution on its underlying nodes as the remote point location. This is useful when you want a portion of geometry to share the same DOF solution (such as UX) that may or may not be known. For example, to constrain a surface to have the same displacement in the X direction, simply create a remote point, set the formulation to Coupled, and activate the X DOF. Because the DOF is known, you can specify an additional Remote Displacement. This formulation is similar to the MAPDL constraint defined by the CP command. Examples of these behaviors are illustrated below. Rigid Behavior

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Remote Point

Deformable Behavior

Coupled Behavior

Support Specifications Note the following when using the Remote Point feature. • MAPDL solver logic is based on MPC-based contact. See the Surface-Based Constraints section of the Mechanical APDL Contact Technology Guide for more information. A Remote Point scoped to a vertex or vertices in a 2D or 3D solid does not use the contact MPC, it creates embedded beams to connect the vertex to the Remote Point. • The MPC equations are generated from the definition of a Remote Point are based on the underlying element shape functions. In a large deflection analysis, element shapes are reformed each substep. As a result, MPC equations are superior to the RBE3, CERIG, and CP commands.

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Specifying Geometry • You must determine which Behavior best represents the actual loading. Note that this option has no effect if the boundary condition is scoped to a rigid body in which case a Rigid behavior is always used. Presented below are examples of the Total Deformation resulting from the same Remote Displacement (illustrated above), first using a Rigid formulation, then using a Deformable formulation, and finally the Coupled formulation. • For Remote Boundary Conditions applied to an edge or edges of a line body that are colinear, the deformable behavior is invalid. As such, the scoped entities exhibit rigid behavior even if a deformable formulation is specified, and a warning is issued in the Message Window. • All remote boundary conditions are associative, meaning they remember their connection to the geometry. Their location however does not change. If you want the location to be associative, create a coordinate system on the particular face and set the location to 0,0,0 in that local coordinate system. • If the geometry to which a Remote Point is scoped becomes suppressed, the Remote Point also becomes suppressed. Once the geometry is Unsuppressed, the Remote Point becomes valid again. • Remote boundary conditions scoped to a large number of elements can cause the solver to consume excessive amounts of memory. Point masses in an analysis where a mass matrix is required and analyses that contain remote displacements are the most sensitive to this phenomenon. If this situation occurs, consider modifying the Pinball setting to reduce the number of elements included in the solver. Forcing the use of an iterative solver may help as well. Refer to the troubleshooting section for further details. • If a remote boundary condition is scoped to rigid body, the underlying topology on which the load is applied is irrelevant. Since the body is rigid, the loading path through the body will be of no consequence; only the location at which the load acts. For additional MAPDL specific information, see the Multipoint Constraints and Assemblies section as well as KEYOPT(2) in the Mechanical APDL Contact Technology Guide.

Note To apply a remote boundary condition scoped to a surface more than once (for example, two springs), you must do one of the following: • Set scoped surface Behavior to Deformable. • Change scoping to remove any overlap. • Leverage the Pinball Region option.

Remote Point Features Use the following tools to get the most out of the Remote Point feature. • View Remote Points through Connection Lines • Promote Remote Points • Program Remote Points with Commands Objects

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Remote Point

View Remote Points through Connection Lines The connection between the underlying geometry associated with a remote point and the remote point itself can be visualized by connection lines. You can enable this feature through the Show Connection Lines property under Graphics in the Details view of the Remote Points object. If a mesh was generated, the connection lines are drawn between a remote point and the nodes on the corresponding meshed underlying geometry. The connection lines take the Pinball radius into account, and only those nodes that are inside that radius will be connected with the remote point. Any remote loads that have been promoted to reference remote points will have these lines drawn when their object is selected as well. An example illustration of connection lines is shown below.

See the Viewing and Exporting Finite Element Connections topic in the Solution Information Object section of the Help for additional information about the ability to view and work with connection lines.

Promote Remote Points The Promote Remote Point feature helps you add a remote point from the context menu for remote boundary conditions. When you use Promote Remote Point, Workbench adds a remote point object with the remote boundary condition name and the associated data in the Project tree. To add a remote point from a remote boundary condition: 1.

On the Environment context toolbar, select the appropriate boundary condition.

2.

Right-click the remote boundary condition object, and then select Promote Remote Point. A remote point with the boundary condition name and data is added to the Project tree.

3.

In the Project tree, select the new remote point object and modify its data as necessary.

Note This option is not available for objects scoped as a Direct Attachment, such as Springs, Joints, Beams, or a Point Mass. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Specifying Geometry

Program Remote Points with Commands Objects A Commands object can be placed in the tree as a child object of a Remote Point providing you programmable access to the Remote Point pilot node. This is useful if you wish to apply conditions to the Remote Point that are not supported in Mechanical, such as beam or constraint equations.

Point Mass You can idealize the inertial effects from a body using a Point Mass. Applications include applying a force with an acceleration or any other inertial load; or adding inertial mass to a structure, which affects modal and harmonic solutions. To define a Point Mass: 1. Select the Geometry object (or a child object). 2. You can then add a Point Mass object by: • Selecting Point Mass from the Geometry toolbar. or... • Right-clicking the mouse button and selecting Insert>Point Mass from the context menu. or... • Select the desired geometry in the graphics window, right-click the mouse, and then select Insert>Point Mass from the context menu. 3. Specify the Scoping Method property as either Geometry Selection, Named Selection, or Remote Point. Based on the selection made in this step, select a: • geometry (faces, edges, or vertices) and click Apply in the Details view for the Geometry property. or... • single node and click Apply in the Details view for the Geometry property. In order to select an individual node, you need to first generate a mesh on the model, and then choose the Show Mesh button on the Graphics Options Toolbar, and then specify Select Mesh as the Select Type from the Graphics Toolbar. or... • user-defined node-based named selection from the drop-down list of the Named Selection property. or... • user-defined remote point from the drop-down list of the Remote Point property. or... 4. Specify the Point Mass as a Remote Attachment (default) or a Direct Attachment using the Applied By property. The Remote Attachment option uses either a user-defined or a system-generated Remote Point as a scoping mechanism. Remote Attachment is the required Applied By property setting if the geometry scoping is to a single face or multiple faces, a single edge or multiple edges, or multiple vertices.

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Thermal Point Mass The Direct Attachment option allows you to scope directly to a single vertex (Geometry) or a node (using an individually selected node or a node-based Named Selection) of the model. 5. Enter a Mass value. 6. Modify Point Mass object Details view properties as needed. The location of the Point Mass can be anywhere in space and can also be defined in a local coordinate system if one exists. The default location is at the centroid of the geometry. The Point Mass will automatically be rotated into the selected coordinate system if that coordinate system differs from the global coordinate system. You can also input moment of inertia values for each direction. A Point Mass is considered a remote boundary condition if you specify it as a Remote Attachment. Refer to the Remote Boundary Conditions (p. 833) section for a listing of all remote boundary conditions and their characteristics.

Support Limitations A Point Mass cannot: • be applied on any shared topology surface. • span multiple bodies if the Stiffness Behavior of the bodies is declared as Rigid (see Rigid Bodies section for additional information). • be applied to a vertex scoped to an end release.

Thermal Point Mass For Transient Thermal analyses, you can idealize the thermal capacitance of a body using a thermal point mass. Thermal Capacitance replaces the need to calculate the body's internal thermal gradient. The Thermal Point Mass is commonly used as a medium to store or draw heat from surrounding objects. Applications include the heat dissipation of refrigerators, cooling electronic devices, and heat sinks of computer motherboards. This section examines the following feature applications and requirements: • Apply Thermal Point Mass Object • Behavior Property Specifications • Support Limitations

Apply Thermal Point Mass Object To define a Thermal Point Mass in your Transient Thermal analysis: 1. Select the Geometry object (or a child object). 2. You can then add a Thermal Point Mass object by: • Selecting Thermal Point Mass from the Geometry toolbar. or...

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Specifying Geometry • Right-clicking the mouse button and selecting Insert>Thermal Point Mass from the context menu. or... • Select the desired geometry in the graphics window, right-click the mouse, and then select Insert>Thermal Point Mass from the context menu. 3. Specify the Scoping Method property as either Geometry Selection, Named Selection, or Remote Point. Based on the selection made in this step, select a: • face, edge, or vertex of a solid or surface model or on an edge or vertex of a surface model and click Apply in the Details view for the Geometry property. or... • single node and click Apply in the Details view for the Geometry property. In order to select an individual node, you need to first generate a mesh on the model, and then choose the Show Mesh button on the Graphics Options Toolbar, and then specify Select Mesh as the Select Type from the Graphics Toolbar. or... • user-defined node-based named selection from the drop-down list of the Named Selection property. or... • user-defined remote point from the drop-down list of the Remote Point property. 4. Specify the Thermal Point Mass as a Remote Attachment (default) or a Direct Attachment using the Applied By property. The Remote Attachment option uses either a user-defined or a system-generated Remote Point as a scoping mechanism. Remote Attachment is the required Applied By property setting if the geometry scoping is to a single face or multiple faces, a single edge or multiple edges, or multiple vertices. The Direct Attachment option allows you to scope directly to a single vertex (Geometry) or a node (using an individually selected node or a node-based Named Selection) of the model. 5. Modify coordinate system properties as needed. 6. Enter a Thermal Capacitance value. Thermal Capacitance refers to ability of the material to store heat. The higher the thermal capacitance, the more heat can be stored for each degree rise in temperature of the Thermal Point Mass. 7. When the Thermal Point Mass is defined as a Remote Attachment, the Behavior property displays: define as Isothermal, Coupled, or Heat-Flux Distributed. See the Behavior Property Specifications topic below for additional information about how to make the appropriate selection. 8. Modify additional Thermal Point Mass object Details view properties as needed. The location of the Thermal Point Mass can be anywhere in space. The default location is at the centroid of the geometry. If you specify a Thermal Point Mass (which resembles a Point Mass) as a Remote Attachment, it will act like a remote boundary condition because the Thermal Point Mass is not applied directly to a node of the model. Refer to the Remote Boundary Conditions section of the Help for a listing of all remote boundary conditions and their characteristics.

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Cracks

Behavior Property Specifications The Thermal Point Mass includes three Behavior options in the Details View that control its interaction with the bodies in the geometry selection: Isothermal, Coupled, and Heat-Flux Distributed: • For the Isothermal behavior, temperatures throughout the geometry selections and the Thermal Point Mass are constrained to be the same. The following is an example of a Thermal Point Mass using Isothermal behavior applied to the FACE while a temperature boundary condition is located at the EDGE. While there is a temperature distribution from the boundary condition (EDGE) up to the surface (FACE), the temperature on the FACE in the pinball region, itself takes a single value that matches that of the Thermal Point Mass.

• For Heat-Flux Distributed behavior, however, the temperature of the geometry selection and the point mass are not constrained to be the same. The temperature of the Thermal Point Mass becomes a weighted average of those on the geometry selection. For comparison, the previous example has been modified to use the Heat-Flux Distributed behavior. The FACE, no longer constrained to be isothermal to the point mass, displays a gradient.

• For Coupled behavior, the geometry has the same DOF solution on its underlying nodes as the remote point location. This formulation is similar to the MAPDL constraint defined by the CP command.

Support Limitations A Thermal Point Mass cannot be applied: • on any shared topology surface. • to a vertex scoped to an end release.

Cracks A crack is characterized by its shape, crack front/tip, crack discontinuity plane, crack normal, and crack direction. A crack front in three dimensional analyses represents the line of separation of the discontinuRelease 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Specifying Geometry ous crack surface. The same is represented by a crack tip in two dimensional analyses. A crack inside ANSYS Mechanical is defined using a Crack object or Pre-Meshed Crack object. These objects can be inserted under the Fracture folder. Crack objects, for which you define geometry parameters that define the generated crack mesh, is used to analyze crack front. Internally, the crack mesh generation is performed after the creation of the base mesh. The geometric parameters define the semi-elliptical shape of the crack in three dimensional analyses. The crack definition is complete only after the successful generation of the crack mesh. By default, the crack mesh generation automatically creates a node-based named selection for the crack front under the crack object. For information about the Crack object that uses an internally generated mesh, see Fracture Meshing in the Meshing User's Guide. A Pre-Meshed Crack definition assumes that the crack meshes, representing the discontinuity or flaw in the structure, have already been generated. In other words, the pre-meshed crack does not internally generate the crack mesh using Fracture Meshing, as the Crack object does, but instead assumes that the crack mesh has been generated beforehand. A Pre-Meshed Crack object uses a node-based named selection to analyze crack front; this nodal named selection is required for the computation of fracture parameters. If a geometric edge represents a crack front, you must first convert it to a node-based named selection using the Worksheet criteria before it can be used by the Pre-Meshed crack object. See the next section, Defining a Pre-Meshed Crack (p. 473), for more information on the Pre-Meshed Crack. The orientation of the crack plays a vital role in the fracture parameter calculations. The coordinate system assigned to a Crack or Pre-Meshed Crack object must be defined such that the y-axis is normal to the crack surface while the x-axis is pointing along the crack extension direction. For the Crack object, the x-axis of coordinate system must be aligned normal to the surface of the scoped geometric entity, which implies that cracks must be perpendicular to the surface (cracks cannot be created at an incline). To achieve this alignment, create a coordinate system as described in Creating a Coordinate System Based on a Surface Normal (p. 487) and assign the created coordinate system to the Crack object. For the Pre-Meshed Crack object, the origin of the coordinate system must be located on the open side of the crack. After the crack mesh is generated, a warning message Mesher has aligned X-axis to the anchor face normal direction. Please orient the crack coordinate system to the face normal direction for accurate computation of fracture parameters Indicates that one of the active crack coordinate systems is not oriented correctly, which may lead to inaccurate computation of fracture parameters. To identify which coordinate system is not oriented properly, set the Crack coordinate orientation variable to 1 (active) in the Variable Manager. Then re-generate the crack mesh. The error message shown in the Messages window indicates the Crack object that requires coordinate system modification. Orient the respective coordinate system correctly; for more information, see Creating a Coordinate System Based on a Surface Normal (p. 487). After correcting the improperly defined coordinate systems for all cracks, reset the Crack coordinate orientation variable to inactive. Note: The graphical view of the crack may differ from the mesh generated. Possible reasons include: • A crack definition unsuitable for valid mesh creation may result in some layers being “peeled off” to create a valid mesh. • The crack contour may be shrunk to fit into the mesh domain.

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Cracks • The crack coordinate system may be changed to align it to surface normal. • The center of the crack may be changed to create the crack on the surface. • The crack is meshed with gradation from the contour center to the outside results in difficulty distributing the crack mesh. • The offset of the crack is not suitable for the crack contour, resulting in a contour that must be reduced to ensure all element contours fit into the template.

Defining a Pre-Meshed Crack A Pre-Meshed Crack is based on a previously-generated mesh and uses a node-based named selection to analyze crack fronts. In addition to cracks modeled in CAD and meshed manually in the Mechanical Application, this feature is also useful when you have a pre-existing mesh generated from an external source and imported to the existing database using FE Modeler. The referenced named selection must contain references only to nodes. Selecting the named selection is done through the Details view of the Pre-Meshed Crack object by selecting from the list of valid named selections in the Crack Front (Named Selection) property. Named selections that contain only nodes are offered as choices.

Note Before defining a pre-meshed crack, you must have defined at least one node-based named selection. For more information on named selections, see Named Selections (p. 429). As an alternative, a geometric based named selection can be converted into a node-based based named selection using the Worksheet. For more information, see Specifying Named Selections using Worksheet Criteria (p. 434). To define a pre-meshed crack: 1.

Select the Model object in the Tree Outline.

2.

Insert a Fracture object into the Tree by right-clicking the Model object and selecting Insert > Fracture.

Note Only one Fracture object is valid per Model.

3.

Insert a Pre-Meshed Crack object into the Tree by right-clicking the Fracture object and selecting Insert > Pre-Meshed Crack.

4.

In the Details View: • For 2D analysis, for Crack Tip (Named Selection), select the node-based named selection to which the crack definition will be scoped.

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Specifying Geometry • For 3D analysis, for Crack Front (Named Selection), select the node-based named selection to which the crack definition will be scoped.

Note For a complete Pre-Meshed Crack definition, you must have previously defined the scoped node-based named selection and generated all crack meshes.

5.

To further define the crack, use the following controls in the Details View. • Coordinate System: Specifies the coordinate system that defines the position and orientation of the crack. The Y axis of the specified coordinate system defines the crack surface normal. The origin of the coordinate system represents the open side of the crack. You can select the default coordinate system or a local coordinate system that you have defined. The default is the Global Coordinate System. The valid coordinate system must be of type Cartesian. • Solution Contours: Specifies the number of contours for which you want to compute the fracture result parameters. • Suppressed: Toggles suppression of the Pre-Meshed Crack object. The default is No.

Note The Pre-Meshed Crack object is suppressed automatically if the scoped body is suppressed.

Interface Delamination and Contact Debonding Adhesives are commonly used to bond structural components into assemblies or to bond layers of material into composite laminates. Simulations often assume the bonding layer to be of infinite strength, but you may want to model the progressive separation of the adhesive as it reaches some known criteria, such as a stress limit. Of the existing theories that define these failure criteria, Mechanical supports the Cohesive-Zone Model (CZM) method and the Virtual Crack Closure Technique (VCCT) method. (See the Cohesive Zone Material (CZM) Model section of the Mechanical APDL Theory Reference and the VCCTBased Crack Growth Simulation section of the Mechanical APDL Structural Analysis Guide for more information about these methods.) In either case, the separation occurs along a predefined interface and cannot propagate in an arbitrary direction Mechanical supports the following features for modeling interface delamination and debonding: • Interface Delamination – utilizes MAPDL interface elements (INTER202 through INTER205) and supports the CZM and VCCT methods. Neither method supports interfaces with lower order triangle faces. Specifically, a prism with a triangle face on the interface or a tetrahedral element with a face on the interface. And, the VCCT does not support higher order elements. • Contact Debonding utilizes MAPDL contact elements (CONTA171 through CONTA177) and supports the CZM method. For additional technical information about Interface Delamination, see the Modeling Interface Delamination with Interface Elements section of the Mechanical APDL Structural Analysis Guide and for 474

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Interface Delamination and Contact Debonding more information about Contact Debonding, see the Modeling Interface Delamination with Contact Elements section. See the Interface Delamination Application and Contact Debonding Application sections for the steps to specify and configure these features. In addition, if you are using the ANSYS Composite PrepPost (ACP) application in combination with the Interface Delamination feature, see the steps in the Interface Delamination and ANSYS Composite PrepPost (ACP) section.

Analysis Type Requirements Interface Delamination is supported by Static Structural and Transient Structural analyses only. Any analysis type may contain a Contact Debonding object, but only the Static Structural and Transient Structural analyses support the progressive separation of an interface. Contact Debonding also supports linear perturbation, which allows you to simulate the vibration (Pre-stressed Modal) or stability (Linear Buckling) characteristics of a partially delaminated structure. You can also use the modes extracted in the Pre-stressed model to perform Mode Superposition analyses such as Harmonic Response, Response Spectrum, and Random Vibration.

Interface Delamination Application The Interface Delamination feature employs either the Virtual Crack Closure Technique (VCCT) method or the Cohesive-Zone Model (CZM) method for defining failure criteria. The VCCT method is a fracture mechanics based method and therefore requires an initial crack (in the form of a Pre-Meshed Crack) in the geometry. The CZM method uses relationships between the separations and tractions along the interface. Note that the CZM method is sensitive to mesh size and material parameters. The convergence of CZM models can generate issues, such as loading step size and stabilization. You may want to review the Interface Delamination Analysis of Double Cantilever Beam tutorial available in the Appendix B. Tutorials section of the Help. To correctly insert the structural interface elements (INTER202 through INTER205) into the mesh, the Interface Delamination feature requires that the sides of the interface have identical element patterns. Both the VCCT and CZM methods provide the option to use either the Matched Meshing or the Node Matching generation method. Matched Meshing requires that you create a Mesh Match Control at the delamination interface. A Match Control requires that both faces referenced by the Match Control belong to the same part, so it is necessary that you create a multi-body part without shared topology. This can be accomplished in a CAD application, such as DesignModeler. Matched Meshing is the recommended Generation Method because it quickly obtains the matching node pairs from the mesh.

Caution The application will not respect mesh matching controls when one or more mesh Refinement controls exist. This may result in mismatched node pairs and element faces. If using a Match Control is not an option and it is necessary to use the Node Matching method, you must ensure that node pairs and element faces match. Because it is necessary for Mechanical to search

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Specifying Geometry the scoped geometry for matching node pairs within the specified Distance Tolerance, this method can be slower and less robust than the Matched Meshing method.

Note The Interface Delamination feature does not support adaptive mesh refinement. Also see the Interface Delamination Object Reference page for information about the properties of this feature. Apply Interface Delamination To specify Interface Delamination: 1. Insert a Fracture folder in the Tree Outline. The Fracture object becomes active by default. 2. On the Fracture context toolbar: click Interface Delamination. Or, right-click: • the Fracture tree object and select Insert>Interface Delamination. Or... • in the Geometry window and select Insert>Interface Delamination. 3. Select the desired Method: either VCCT (default) or CZM. The properties vary based on your selection. VCCT Method 1. Specify the Failure Criteria Option property: either Energy-Release Rate (default) or Material Data Table. 2. Based on the selected Failure Criteria Option: • If specified as Energy-Release Rate: enter a Critical Rate value. This value determines the energy release rate in one direction. • If specified as Material Data Table: specify a Material. This property defines the energy release rate in all three fracture modes. This property is defined in Engineering Data. See the Static Structural & Transient Structural section of the Engineering Data Help for additional information about the Cohesive Zone properties used by this feature. 3. Based on the Generation Method selected, either Matched Meshing (default) or Node Matching, perform one of the following: Matched Meshing If Matched Meshing, specify a Match Control by selecting a pre-defined Match Control. The Match Control that is referenced by the property requires that the delamination occurs between two independent parts that have the same element/node pattern. Node Matching If Node Matching, specify: a. Scoping Method b. Source 476

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Interface Delamination and Contact Debonding c. Target

Note This option assumes that the existing mesh is already matched.

4. Define the Initial Crack by selecting a user-defined Pre-Meshed Crack. 5. Specify the Auto Time Stepping property as either Program Controlled (default) or Manual. The following properties can be modified if Manual is selected, otherwise they are read-only. a. Initial Time Step b. Minimum Time Step c. Maximum Time Step

Note • The Auto Time Stepping property must be set to On in the Step Controls category of the Analysis Setting object. • Time stepping values take effect when crack growth is detected.

6. If Node Matching is selected as the Generation Type, the Node Matching Tolerance category displays. Specify the Tolerance Type property as either Program Controlled (default) or Manual. The Distance Tolerance property can be modified if Manual is selected, otherwise it is read-only. CZM Method 1. Specify a Material. This property is defined in Engineering Data. See the Static Structural & Transient Structural section of the Engineering Data Help for additional information about the Cohesive Zone properties used by this feature. 2. Define the Generation Method property as either Matched Meshing (default) or Node Matching. 3. Based on the Generation Method selected, either Matched Meshing or Node Matching, perform one of the following: Matched Meshing For the Matched Meshing Generation Method, select a pre-defined Match Control. The Match Control that is referenced by the property requires that the delamination occurs between two independent parts that have the same element/node pattern. Node Matching If Node Matching is the Generation Method, then specify: a. Scoping Method b. Source Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Specifying Geometry c. Target

Note This option assumes that the existing mesh is already matched.

4. If Node Matching is selected as the Generation Type, the Node Matching Tolerance category displays. Specify the Tolerance Type property as either Program Controlled (default) or Manual. The Distance Tolerance property can be modified if Manual is selected, otherwise it is read-only.

Contact Debonding Application Debonding simulations begin by defining contact regions along an interface that will separate. The properties for the contact elements require that the contact Type be Bonded or No Separation contact and that the Formulation is specified as the Augmented Lagrange method or the Pure Penalty method. The Contact Debonding object specifies the pre-existing contact region (defined using the Connections feature) that you intend to separate and it also references the material properties defined in Engineering Data. You must select the material properties from the Cohesive Zone category with type SeparationDistance based Debonding or Fracture-Energies based Debonding. See the Static Structural & Transient Structural section of the Engineering Data Help for additional information about the Cohesive Zone properties used by this feature. In addition, you may want to review the Delamination Analysis using Contact Based Debonding Capability tutorial available in the Appendix B. Tutorials section of the Help. Apply Contact Debonding To specify Contact Debonding: 1. Insert a Fracture folder in the Tree Outline. The Fracture object becomes active by default. 2. On the Fracture context toolbar: click Contact Debonding. Or, right-click: • the Fracture tree object and select Insert>Contact Debonding. Or... • in the Geometry window and select Insert>Contact Debonding. 3. Select a Material. 4. Select a Contact Region.

Tip To automatically generate a Contact Debonding object, select a Contact Region and drag and drop it onto the Fracture folder.

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Interface Delamination and Contact Debonding Also see the Contact Debonding Object Reference Help page for information about the properties of this feature.

Interface Delamination and ANSYS Composite PrepPost (ACP) Mechanical allows you to import interface layer(s) from the ANSYS Composite PrepPost (ACP) application. You can define interface layers in ACP, import them into Mechanical, and use them to define Interface Delamination objects. You can automatically insert Interface Delamination objects into the Fracture folder when importing composite section data into Mechanical by setting the Create Delamination Objects property (see Specifying Options) to Yes. Alternatively, you can generate Interface Delamination objects automatically after you have imported Composite Section data by selecting the Generate All Interface Delaminations option in the context menu of the Fracture object.

Unexpected Penetration during Nonlinear Analysis If you experience penetration at the interface layers during separation, you may wish to create a Contact condition for the interface where the penetration is taking place. A Contact Region can be applied to a Pre-Generated Interface provided by ACP. Although all contact Type settings are supported for PreGenerated Interfaces, the Frictionless setting is recommended for this case when specifying the contact condition. Other contact properties can be set to the default, Program Controlled, settings.

Apply Interface Delamination via ACP To specify Interface Delamination using the ACP application:

Note The following steps assume that you have properly defined your interface layer in the ACP application. VCCT Method (Default) 1. From the Workbench Project page, link your Static Structural or Transient Structural analysis to the ACP (Pre) system and then launch Mechanical. A Fracture folder is automatically created and includes an Interface Delamination object. 2. Select the new Interface Delamination object. 3. Specify the Failure Criteria Option property: either Energy-Release Rate (default) or Material Data Table. 4. Based on the selected Failure Criteria Option: • If specified as Energy-Release Rate: enter a Critical Rate value. This value determines the energy release rate in one direction. • If specified as Material Data Table: specify a Material. This property defines the energy release rate in all three fracture modes. This property is defined in ACP. 5. The automatic setting for the Generation Method property is Pre-Generated Interface. Accept this setting.

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Specifying Geometry 6. As necessary, select the appropriate Interface Layer from the Interface property drop-down menu. 7. Define the Initial Crack by selecting the Pre-Meshed Crack created by ACP. 8. Specify the Auto Time Stepping property as either Program Controlled (default) or Manual. The following properties can be modified if Manual is selected, otherwise they are read-only. a. Initial Time Step b. Minimum Time Step c. Maximum Time Step

Note • The Auto Time Stepping property must be set to On in the Step Controls category of the Analysis Setting object. • Time stepping values take effect when crack growth is detected.

CZM Method 1. From the Workbench Project page, link your Static Structural or Transient Structural analysis to the ACP (Pre) system and then launch Mechanical. A Fracture folder is automatically created and includes an Interface Delamination object. 2. Select the new Interface Delamination object. 3. Specify the Material property. This property provides a fly-out menu to make a material selection that was defined in the ACP (Pre) system. 4. The automatic setting for the Generation Method property is Pre-Generated Interface. Accept this setting. 5. As necessary, select the appropriate Interface Layer from the Interface property drop-down menu.

Gaskets Gasket joints are essential components in most structural assemblies. Gaskets as sealing components between structural components are usually very thin and made of various materials, such as steel, rubber and composites. From a mechanics perspective, gaskets act to transfer force between components. The primary deformation of a gasket is usually confined to one direction, namely, through thickness. The stiffness contributions from membrane (in plane) and transverse shear are much smaller in general compared to the through thickness. A typical example of a gasket joint is in engine assemblies. A thorough understanding of the gasket joint is critical in engine design and operation. This includes an understanding of the behavior of gasket joint components themselves in an engine operation, and the interaction of the gasket joint with other components. The overall procedure for simulating gaskets in ANSYS Workbench is to run a static structural analysis and perform the following specialized steps:

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Gaskets 1. Specify a material with a valid gasket model in Engineering Data. 2. Set the Stiffness Behavior of the Body object to Gasket. This produces a Gasket Mesh Control object beneath the Body object. 3. Adjust Details view settings for the Gasket Mesh Control object and generate the mesh. 4. Solve and review the gasket result. Refer to the following sections for further details. Gasket Bodies Gasket Mesh Control Gasket Results

Gasket Bodies You can conveniently specify a solid body to be treated as a gasket by settings its Stiffness Behavior to Gasket. A Gasket body will be meshed with special elements that have a preferential or sweep direction. The mesh will consist of a single layer of solid elements with all mid-side nodes dropped along this direction. You must also specify a material with a valid gasket model in Engineering Data. The following restrictions apply to Gasket bodies: • Gasket bodies are valid only in static structural analyses. • Gasket bodies are valid for 3D solids only, that is, 2D gasket bodies cannot be specified. • A valid gasket material model must be specified. • In addition to gasket bodies, a multibody part may also include flexible bodies but not rigid bodies.

Gasket Mesh Control Upon specifying a Gasket body, a Gasket Mesh Control object is added beneath the Body object in the tree. The meshing method for the control will be set to sweep and allow you to indicate the sweep direction. This control instructs the application to drop mid-side nodes on gasket element edges that are parallel to the sweep direction. To use gasket element meshing after setting the 3D Body object's Stiffness Behavior to Gasket: 1. In the Details view of the Gasket Mesh Control object, ensure that Mesh Method is set to Sweep and Src/Trg Selection is set to Manual Source. These are the default settings. 2. Select a Source face. The selected face must lie on the gasket body. 3. The Target selection is Program Controlled by default. If desired, you can set Src/Trg Selection to Manual Source and Target. Then you can choose Target manually. 4. If desired, you can change the value of the Free Face Mesh Type control to All Quad, Quad/Tri, or All Tri. When generating the gasket element mesh, the application drops the midside nodes on the edges that are parallel to the sweep direction. For example, consider the mesh shown below. To define the sweep method, Src/Trg Selection was set to Manual Source; one face (the “top” face) was selected for Source.

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Specifying Geometry In the resulting mesh, the gasket element faces on the source and target are quadratic, but the faces on the sides are linear.

Note When Element Midside Nodes is set to either Program Controlled or Kept results in quadratic elements with midside nodes are dropped in the normal direction. When Element Midside Nodes is set to Dropped the midside nodes are dropped, resulting in linear elements.

Gasket Results Specialized results are available for analyzing gaskets. See Gasket Results (p. 948) for details.

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Setting Up Coordinate Systems All geometry in the Mechanical application is displayed in the global coordinate system by default. The global coordinate system is the fixed Cartesian (X, Y, Z) coordinate system originally defined for a part. In addition, you can create unique local coordinate systems to use with springs, joints, various loads, supports, and result probes. Cartesian coordinates apply to all local coordinate systems. In addition, you can apply cylindrical coordinates to parts, displacements, and forces applied to surface bodies.

Note Cylindrical coordinate systems are not supported by the Explicit Dynamics solvers, but may be used for some postprocessing operations. Annotations are available for coordinate systems. You can toggle the visibility of these annotations in the Annotation Preferences dialog box. For more information, see Specifying Annotation Preferences (p. 119). The following topics are covered in this section: Creating Coordinate Systems Importing Coordinate Systems Applying Coordinate Systems as Reference Locations Using Coordinate Systems to Specify Joint Locations Creating Section Planes Create Construction Surface Transferring Coordinate Systems to the Mechanical APDL Application

Creating Coordinate Systems The following topics involve the creation of local coordinate systems: Initial Creation and Definition Establishing Origin for Associative and Non-Associative Coordinate Systems Setting Principal Axis and Orientation Using Transformations Creating a Coordinate System Based on a Surface Normal See the Coordinate System Object Reference page of the Help for additional information about the categories and properties of the Coordinate System object.

Initial Creation and Definition Creating a new local coordinate system involves adding a Coordinate System object to the tree and addressing items under the Definition category in the Details view.

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Setting Up Coordinate Systems To create and define a new local coordinate system: 1. Highlight the Coordinate Systems folder in the tree and choose the Coordinate Systems button from the toolbar or from a right-click and select Insert> Coordinate System. A Coordinate System object is inserted into the tree.

The remainder of the toolbar buttons involve the use of transformations discussed in a later section. 2. In the Details view Definition group, set the following: a. Type: set to Cartesian or Cylindrical. b. Coordinate System: to Program Controlled or Manual. This assigns the coordinate system reference number (the first argument of the Mechanical APDL LOCAL command). Choose Program Controlled to have the reference number assigned automatically, or choose Manual to assign a particular reference number in the Coordinate System ID field for identification or quick reference of the coordinate system within the input file. You should set the Coordinate System ID to a value greater than or equal to 12. If you create more than one local coordinate system, you must ensure that you do not duplicate the Coordinate System ID. c. Suppressed: Yes or No (default). If you choose to suppress a coordinate system, you remove the object from further treatment, write no related data to the input deck, and cause any objects scoped to the coordinate system to become underdefined (therefore invalidating solutions).

Establishing Origin for Associative and Non-Associative Coordinate Systems After creating a local coordinate system, you can further designate it as being associative or non-associative with geometry and define its origin. • An associative coordinate system remains joined to the face or edge on which it is applied throughout preprocessing. Its position and orientation is thus affected by modifications to the geometry during updates and through the use of the Configure tool. The coordinate system does not follow the geometry and its mesh during the solution. • A non-associative coordinate system is independent of any geometry. You establish the origin for either an associative or non-associative coordinate system in the Origin category in the Details view. The category provides the following properties: • Define By: options include Geometry Selection, Named Selection, and Global Coordinates. • Geometry: this property is a graphical selection tool. The selection you make using this property defines the values populated in the Origin X, Y, and Z properties.

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Creating Coordinate Systems • Origin X, Origin Y, and Origin Z: automatically populated by the Geometry property selection or you can manually enter values.

Note A coordinate system's origin cannot be located by scoping it to a line body. If you wish to put the origin at the center of the line body, please select the edge of the line body for the origin selection instead. To establish the origin for an associative coordinate system: 1. Set the Define By property to Geometry Selection or Named Selection. For a Reference Coordinate System attached to a joint, work with the Orientation About Principal Axis category to make the coordinate system associative. If you select: • Geometry Selection a. Graphically select geometry (vertex or vertices, edge, face, cylinder, circle, or circular arc) or one node or multiple nodes. b. Select the Geometry field and then select Click to Change. c. Click Apply. A coordinate system symbol displays at the centroid of your selection. The centroid is defined as the simple average (unweighted by length, area, or volume) of the individual centroids of your geometry selections. • Named Selection: Select a user-defined Named Selection from the Named Selection drop-down menu. Preselecting one or more topologies and then inserting a Coordinate System will automatically locate its origin as stated above. To establish the origin for a non-associative coordinate system: •

In the Details view Origin group, set Define By to Global Coordinates. You then define the origin in either of the following ways: • Selecting any point on the exterior of the model: 1. Set Define By to Global Coordinates. 2. Select the Click to Change field of the Location property. 3. Select the Hit Point Coordinate ( ) button on the Graphics Toolbar. This feature allows you to move the cursor across the model and display coordinates. 4. Select the desired origin location on the model. A small cross hair appears at the selected location. You can change the cross hair location as desired. 5. Click Apply in the Location property field. A coordinate system symbol displays at the origin location. Note that the coordinates display in Origin X, Y and Z properties of the the Details view.

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Setting Up Coordinate Systems You can change the location by repositioning the cursor, clicking at the new location, and then clicking Click to Change and Apply, or by editing the coordinates in the Details view. • Selecting any point using the average location of selected nodes: 1. Set Define By to Global Coordinates. 2. Choose Click to Change in the Location row. 3. Click the Show Mesh button.

4. Choose the Select Mesh option in the Select Type (Geometry/Mesh) menu.

5. Select as many nodes as desired and then click Apply. The origin coordinate system is specified on the model based on the average location of the selected nodes. • Entering the coordinates directly in the Details view. 1. Set Define By to Global Coordinates. 2. Type the Origin X, Y, Z coordinates. The origin will be at this location.

Setting Principal Axis and Orientation The definition of the coordinate system involves two vectors, the Principal Axis vector and the Orientation About Principal Axis vector. The coordinate system respects the plane formed by these two vectors and aligns with the Principal Axis. Use the Principal Axis category in the Details view to define one of either the X, Y, or Z axes in terms of a: • Geometry Selection – Associatively align axis to a topological feature in the model. When a change occurs to the feature, the axis automatically updates to reflect the change. • Fixed Vector – Depending upon the Geometry Selection, this option preserves the current Geometry Selection without associativity. When a change occurs to the feature the axis will not update automatically to reflect that change. • Global X, Y, Z axis – Force the axis to align to a global X, Y, or Z axis. • Hit Point Normal – Align the axis along a normal vector which represents the normal direction of the local surface curvature of the hit point. You then select a point on the screen to define the Hit Point Normal and orient the primary axis. For information on creating a coordinate system aligned with the hit point, see Creating a Coordinate System Based on a Surface Normal (p. 487). Use the Orientation About Principal Axis category in the Details view to define one of the orientation X, Y, or Z axes in terms of the Default, Geometry Selection, the Global X, Y, Z axes, or Fixed Vector.

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Creating Coordinate Systems

Using Transformations Transformations allow you to “fine tune” the original positioning of the coordinate system. Options are available for offsetting the origin by a translation in each of the x, y and z directions, as well as by rotation about each of the three axes. Flipping of each axis is also available. To exercise transformations, you use buttons on the Coordinate System Context Toolbar and settings in the Transformations category in the Details view. To transform a coordinate system: 1.

Choose a transformation (translation, rotation, or flip) from the Coordinate Systems toolbar.

Entries appear in the Details view as you add transformations. 2.

Enter information in the Details view for each transformation.

3.

If required: • Reorder a transformation by highlighting it in the Details view and using the Move Transform Up or Move Transform Down toolbar button. • Delete a transformation by highlighting it in the Details view and using the Delete Transform toolbar button.

Creating a Coordinate System Based on a Surface Normal You can orient a coordinate system based on the surface normal. You have two options. You can orient the principal axis based on the hit point normal of an existing coordinate system, or you can create an aligned coordinate system based on the hit point.

Orienting the Principal Axis by Hit Point Normal To orient the principal axis based on the hit point normal of an existing coordinate system: 1.

Create a coordinate system.

2.

In the Details view, define the principal axis by Hit Point Normal.

3.

In the Graphics window, select a point.

4.

In the Details view, click Apply for Hit Point Normal.

For more information, see Setting Principal Axis and Orientation (p. 486).

Creating a Coordinate System Aligned with a Hit Point To create an aligned coordinate system based on the hit point:

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Setting Up Coordinate Systems 1.

Enable Hit Point Coordinate mode by toggling the Hit Point Coordinate button in the Graphics toolbar.

2.

In the Graphics window, select a point.

3.

Right-click the Graphics window and select Create Coordinate System Aligned with Hit Point. Mechanical creates a coordinate system on the location of hit point with the primary axis aligning along the hit point normal. If a hit point is not defined, Mechanical creates a coordinate system on the location of {0,0,0}, with the axis the same as the global coordinate system.

Importing Coordinate Systems Coordinate systems defined when geometry is imported from DesignModeler, Creo Parametric, or SolidWorks will automatically be created in the Mechanical application. For more information, see the Attaching Geometry section under DesignModeler, or see the Notes section under Creo Parametric or SolidWorks in the CAD Integration section of the ANSYS Workbench help. If you update the model in the Mechanical application, coordinate systems from these products are refreshed, or newly defined coordinate systems in these products are added to the model. If a coordinate system was brought in from one of these products but changed in the Mechanical application, the change will not be reflected on an update. Upon an update, a coordinate system that originated from DesignModeler, Creo Parametric, or SolidWorks will be re-inserted into the object tree. The coordinate system that was modified in the Mechanical application will also be in the tree.

Applying Coordinate Systems as Reference Locations Any local coordinate systems that were created in the Mechanical application, or imported from DesignModeler, Creo Parametric, or SolidWorks, can be applied to a part, or to a Point Mass, Spring, Acceleration, Standard Earth Gravity, Rotational Velocity, Force, Bearing Load, Remote Force, Moment, Displacement, Remote Displacement, or Contact Reaction. This feature is useful because it avoids having to perform a calculation for transforming to the global coordinate system. To apply a local coordinate system: 1.

Select the tree object that represents one of the applicable items mentioned above.

2.

For an Acceleration, Rotational Velocity, Force, Bearing Load, or Moment, in the Details view, set Define By, to Components, then proceed to step 3. For the other items, proceed directly to step 3.

3.

In the Details view, set Coordinate System to the name of the local coordinate system that you want to apply. The names in this drop-down list are the same names as those listed in the Coordinate Systems branch of the tree outline.

Note If you define a load by Components in a local coordinate system, changing the Define By field to Vector will define the load in the global coordinate system. Do not change the Define By field to Vector if you want the load defined in a local coordinate system.

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Creating Section Planes

Using Coordinate Systems to Specify Joint Locations Whenever you create a joint, an accompanying reference coordinate system is also created. The intent of this coordinate system is for positioning the joint. See the Joint Properties (p. 553) section for further details.

Creating Section Planes For viewing purposes, you can use the Create Section Plane option to slice the graphical image of your model based on a predefined coordinate system.

Note The Section Plane feature does not support Cylindrical Coordinate Systems. 1. Select the desired Coordinate Systems object. The User-Defined Coordinate System illustrated here slices the model along the X-Y plane.

2. Right-click the mouse and select Create Section Plane.

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Setting Up Coordinate Systems

As illustrated here, the model is sliced based on the User-Defined Coordinate System.

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Create Construction Surface

Note This option is also available for Coordinate System objects in the Meshing Application.

Create Construction Surface As illustrated below, you can create a Surface Construction Geometry from any existing coordinate system using the right-click feature Create Construction Surface. Right-click Menu for Create Construction Surface

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Setting Up Coordinate Systems

Details for Surface Object

The Details display the defined coordinate system and allow you to suppress the object if desired.

Transferring Coordinate Systems to the Mechanical APDL Application You can transfer coordinate systems to the Mechanical APDL application using any of the following methods: • Main Menu> Tools > Write Input File... • Load the Mechanical APDL application. • Commands Objects Any coordinate system defined in the Mechanical application and sent to the Mechanical APDL application as part of the finite element model, will be added to the Mechanical APDL application input file as LOCAL commands. For example: /com,*********** Send User Defined Coordinate System(s) *********** local,11,0,0.,0.,0.,0.,0.,0. local,12,1,11.8491750582796,3.03826387968126,-1.5,0.,0.,0. csys,0

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Setting Connections Supported connection features consist of Contact, Mesh Connection, Joint, Spring, Beam Connection, End Release, Spot Weld and Body Interaction (Explicit Dynamics only). Each of these connections can be created manually in the application. Only Contact, Joint, and Mesh Connection can also be generated automatically. This section describes Connections folder, Connection Group folder, Automatic Generated Connections, as well as each connection type as outlined below. Connections Folder Connections Worksheet Connection Group Folder Common Connections Folder Operations for Auto Generated Connections Contact Joints Mesh Connection Springs Beam Connections Spot Welds End Releases Body Interactions in Explicit Dynamics Analyses Bearings

Connections Folder The Connections folder is the container for all types of connection objects except for the three types that can be automatically generated (Contact, Joint, and Mesh Connection). The objects of each of these three types are placed in a sub-folder called the Connection Group folder. As illustrated below, the Details view of the Connections folder provides the following two properties.

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Setting Connections

Auto Detection • Generate Automatic Connection On Refresh: options are Yes (default) or No. This is a setting to turn on/off for auto generation of connection objects when the geometry is refreshed. The process of automatically creating the contact and mesh connection objects is additive. Any existing connection objects of these types that were created manually may be duplicated when the connections are automatically regenerated. To avoid duplication, you should first delete any existing contact and mesh connection objects before the geometry is refreshed.

Note Special conditions apply to updating geometry that includes Spot Welds. The process of automatically creating joint objects is not additive. Any existing joint objects are note duplicated when connections are automatically regenerated. Transparency • Enabled: options are Yes (default) or No. This is a setting to enable or disable transparency of the bodies not associated with the connection in the graphics display.

Connections Worksheet When Connections is selected in the Tree Outline, the Worksheet window supplements the Details view by providing a summary of the contact information, joint information, mesh connection information, and the connections between geometry bodies. In the worksheet, the Show Preferences button enables you to select the worksheet data, and the Generate button generates the content. To toggle on the worksheet:

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Connections Worksheet 1.

Select the Worksheet button on the standard toolbar.

2.

Select the Show Preferences button to view the possible data types.

3.

Select the check boxes for the data types you want to view.

4.

Select the Generate button to generate the content. ANSYS Mechanical remembers the display preferences you select and will default to those in future sessions.

Select Hide Preferences to hide the preferences and Refresh to refresh the worksheet data.

Worksheet Connections Data Types The data types available in the worksheet are described below. You can turn the displayed properties on and off using the right-click menu. Contact Information Displays the properties for each contact. Joint DOF Checker Checks the total number of free degrees of freedom and displays the free DOF, based on the number of unsuppressed parts, fixed constraints, and translation joints. If this number is less than 1, the model may be overconstrained, and you should check the model closely and remove any redundant joint constraints. You can use a Redundancy Analysis to detect redundant joint constraints. Joint Information Displays the name, type, scope, and status of all joints. Mesh Connection Information Displays information about the mesh connections. Spring Information Displays spring connection properties. Beam Information Displays beam connection properties. Connection Matrix Displays a matrix that represents the connections between bodies in the geometry. These connections are color-coded by type (as shown in the legend). In the Preferences, you can choose the type of data to display, in order to filter out unwanted information. Activate the options by checking the selection box beside the Connection Matrix title. The following options can then be selected or deselected as desired. • Show Upper Diagonal • Show Diagonal Marker • Show Unconnected Bodies • Show Suppressed Objects • Bundle Connections The Bundle Connections option is an especially useful tool as it allows you to group Control Connection Types. For example, if you have three Spot Welds contained in the same cell of the Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Setting Connections matrix, activating the Bundle Connections option displays the spot welds as "3 Spot Welds" instead of displaying the individual names of all three within the cell.

Note The matrix displays a grounded connection as a connection to itself. For example, if a grounded joint is scoped to body1, then it will be displayed in the cell of column body1 and row body1. Selection Options Selecting the table, a cell, a row, or a column and the right-clicking the mouse provides a menu of the following options: • Go To Selected Items in Tree: the application displays the associated contact object or objects in the Geometry Window. • Edit Column Width: changes column width (in pixels). You can select multiple columns or rows. A value of zero (default) indicates that the setting is program controlled. • Export (see below)

Note The Connection Matrix is limited to 200 prototypes. Control Connection Types The Control Connection Types display area provides a list of selectable connection features/types that you can choose to display or to not display within the Connection Matrix. Options include: • Contact • Spot Weld • Joint • Mesh Connection • Spring • Beam

Exporting the Connection Matrix You can export a text file version of the Connection Matrix from either the worksheet or the Connections object in the Tree Outline. To export from the worksheet, right-click the Connection Matrix and select Export. To export from the Tree Outline, right-click the Connections object and select Export.

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Connection Group Folder

Connection Group Folder The role of a Connection Group folder is to provide you with the ability to automatically generate Contact, Joint, or Mesh Connection objects for the whole model or for a group of bodies within the model with a tolerance value applied only to this group. Only these three types of connections are provided with the automatic detection capability and only one type of connection objects can be included in a Connection Group folder with the exception of Spot Weld (see details in the Spot Weld section). The generated objects are placed in a Connection Group folder which is automatically renamed to "Contacts", "Joints", or "Mesh Connections" depending on the type. When a model is imported into the Mechanical application, if the Auto Detect Contact On Attach is requested (in the Workbench Tools>Options>Mechanical), auto contact detection is performed using the detection criteria based on the user preferences (in the Mechanical Tools>Options>Connections). Detail steps for auto/manual generating connection objects are presented in the Common Connections Folder Operations for Auto Generated Connections (p. 501) section. The Connection Group has the following properties.

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Setting Connections

Definition • Connection Type: options include Contact, Joint, and Mesh Connections. Scope • Scoping Method: options include Geometry Selection (default) and Named Selection. – Geometry – appears if Scoping Method is set to Geometry Selection. – Named Selection – appears if Scoping Method is set to Named Selection. Auto Detection • Tolerance Type: options include Slider, Value, and Use Sheet Thickness. Bodies in an assembly that were created in a CAD system may not have been placed precisely, resulting in small overlaps or gaps along the connections between bodies. You can account for any imprecision by specifying connection detection tolerance. This tolerance can be specified by value when the type is set to Slider and Value,

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Connection Group Folder or sheet thickness of surface bodies when the type is set to Use Sheet Thickness. This option is only applicable to Contact and Mesh Connection and available when the Group By property (see below) is set to None or Bodies. • Tolerance Slider: appears if Tolerance Type is set to Slider. To tighten the connection detection, move the slider bar closer to +100 and to loosen the connection detection, move the slider bar closer to -100. A tighter tolerance means that the bodies have to be within a smaller region (of either gap or overlap) to be considered in connection; a looser tolerance will have the opposite effect. Be aware that as you adjust the tolerance, the number of connection pairs could increase or decrease. • Tolerance Value: appears if Tolerance Type is set to Slider or Value. This field will be read-only if the Tolerance Type is set to Slider showing the actual tolerance value based on the slider setting. When the Tolerance Type is set to Value, you will be able to provide an exact distance for the detection tolerance. After you provide a greater than zero value for the Tolerance Value, a circle appears around the current cursor location as shown below.

The radius of the circle is a graphical indication of the current Tolerance Value. The circle moves with the cursor, and its radius will change when you change the Tolerance Value or the Tolerance Slider. The circle appropriately adjusts when the model is zoomed in or out. • Use Range: appears when the Tolerance Type property is set to Slider or Value. Options include Yes and No (default). If set to Yes, you will have the connection detection searches within a range from Tolerance Value to Min Distance Value inclusive. – Min Distance Percentage: appears if Use Range is set to Yes. This is the percentage of the Tolerance Value to determine the Min Distance Value. The default is 10 percent. You can move the slider to adjust the percentage between 1 and 100. – Min Distance Value: appears if Use Range is set to Yes. This is a read-only field that displays the value derived from: Min Distance Value = Min Distance Percentage * Tolerance Value/100. • Thickness Scale Factor: appears if Tolerance Type is set to Use Sheet Thickness. The default value is 1. For Edge/Edge pairing (see below), the largest thickness among the surface bodies involved is used; however, if the pairing is Face/Edge, the thickness of the surface body with the face geometry is used. • Face/Face: (Contacts only) options include Yes (default) and No. Detects connection between the faces of different bodies. The maximum allowable difference in the normals for which contact is detected is 15 degrees. For Joints, Face/Face is the only detection type allowed. That is why the property does not appear in the Details view when the Connection Type is Joint.

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Setting Connections • Face/Edge: (Contacts and Mesh Connections only) options include Yes, No (default), Only Solid Body Edges and Only Surface Body Edges. Detects connection between faces and edges of different bodies. Faces are designated as targets and edges are designated as contacts. For Only Solid Body Edges, the face to edge connection uses the edges of solid bodies to determine connection with all faces. Likewise, for Only Surface Body Edges, face to edge connection uses only edges of surface bodies to determine connection with all faces. • Edge/Edge: (Contacts and Mesh Connections only) options include Yes and No. Detects connection between edges of different bodies. • Priority: (Contacts and Mesh Connections only) options include All, Face Overrides and Edge Overrides. For very large models the number of connection objects can sometimes become overwhelming and redundant, especially when multiple detection types are chosen. Selecting some type of priority other than Include All will lessen the number of connection objects generated during Create Automatic Connections by giving designated connection types precedence over other types. Face Overrides gives Face/Face option precedence over both Face/Edge and Edge/Edge options. It also gives Face/Edge option precedence over Edge/Edge option. In general, when Face Overrides priority is set with Face/Edge and Edge/Edge options, no Edge/Edge connection pairs will be detected. Edge Overrides gives Edge/Edge option precedence over both Face/Edge and Face/Face options, no Face/Face connections pairs will be detected. • Group By: options include None, Bodies and Parts. This property allows you to group the automatically generated connections objects. Setting Group By to Bodies (default) or to Parts means that connection faces and edges that lie on the same bodies or same parts will be included into a single connection object. Setting Group By to None means that the grouping of geometries that lie on the same bodies or same parts will not occur. Any connection objects generated will have only one entity scoped to each side (that is, one face or one edge). Applications for choosing None in the case of contact are: – If there are a large number of source/target faces in a single region. Choosing None avoids excessive contact search times in the ANSYS solver. – If you want to define different contact behaviors on separate regions with contact of two parts. For example, for a bolt/bracket contact case, you may want to have bonded contact between the bolt threads/bracket and frictionless contact between the bolt head/bracket. • Search Across: This property enables automatic connection detection through the following options: – Bodies (default): Between bodies. – Parts: Between bodies of different parts, that is, not between bodies within the same multibody part. – Anywhere: Detects any connections regardless of where the geometry lies, including different parts. However, if the connections are within the same body, this option finds only Face/Face connections, even if the Face/Edge setting is turned On. • Fixed Joints: (Joint only) options include Yes and No. This property determines if Fixed Joints are to be automatically generated. See the Automatic Joint Creation section for details. • Revolute Joints: (Joint only) options include Yes and No. This property determines if Revolute Joints are to be automatically generated. See the Automatic Joint Creation section for details.

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Common Connections Folder Operations for Auto Generated Connections

Common Connections Folder Operations for Auto Generated Connections You can automatically generate supported connections for a group of bodies in a model and use a separate tolerance value for that group. The supported connection types are Contact Region, Joint, and Mesh Connection. To automatically generate connections for a group of bodies: 1. Insert a Connection Group object under the Connections folder either from the toolbar button or by choosing Insert from the context menu (right mouse click) for this folder. 2. From the Details view of the Connection Group object, select the desired Connection Type. The default is Contact. 3. Select some bodies in the model based on the Scoping Method. The default is Geometry Selection scoped to All Bodies. 4. If applicable, set the Auto Detection properties. Note that these properties will be applied only to scoped geometries for this connection group. 5. Choose Create Automatic Connections from the context menu (right mouse click) for the Connection Group.

Note For small models, the auto contact detection process runs so fast that the Contact Detection Status (progress bar) dialog box does not get displayed. However, for large models with many possible contact pairs, the progress bar dialog box is displayed showing the contact detection progress. If you click the Cancel button on the dialog box while contact detection is processing, the detection process stops. Any contact pairs found by that moment are discarded and no new contacts are added to the tree. The resulting connection objects will be placed under this folder and the folder name will be changed from its default name Connection Group to a name based on the connection type. The folder name for contacts will be Contacts, for mesh connections it will be Mesh Connections, and for joints it will be Joints. Once the Connection Group folder contains a child object, the Connection Type property cannot be changed. Each Connection Group folder will hold objects of the same type and will include a worksheet that displays only content pertaining to that folder. When two or more Connection Group folders are selected and you choose Create Automatic Connections, auto detection for the selected Connection Group folders will be performed. The Create Automatic Connections option is also available from the context menu (right mouse click) for the Connections folder provided there is at least one Connection Group folder present. When you choose this command from the Connections folder, auto detection will be performed for all connection groups under this folder.

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Manually Inserting Connection Objects You can insert any supported connection objects manually either from the toolbar or by choosing Insert from the context menu (right mouse click) on the Connections or Connection Group folder. When inserting a connection object from the Connections folder, a Connection Group object will automatically be created in addition to the connection object itself. When inserting a connection object from a Connection Group folder, if it is an empty folder, any supported type of object can be inserted. However, if the folder already contains at least one object, only objects of the same type can be inserted.

Searching for Duplicate Pairs Generating connections (Contacts, Mesh Connections or Joints) either automatically or manually may result in the same geometry pair being scoped by more than one connection object. This may over constrain the model that may lead to convergence difficulty problems in the solver. If this situation occurs, you can take corrective action by modifying the geometry scoping of the duplicated pairs or by deleting the duplicating connection objects. When generating connection objects automatically, each newly generated connection will be checked against existing connection objects for possible duplicate pairs. If one or more duplicate pairs are found in the existing connection objects, the following warning message will appear in the message box for a connection object that shares the same geometry pair: "This connection object shares the same geometries with one or more connection objects. This may overconstrain the model. Consider eliminating some connection objects." To find the connection object for a particular message, highlight that message in the message pane and right-click on that message and choose Go To Object from the context menu. The connection object will be highlighted in the tree. In order to find other connection objects that share the same geometry pair, right-click on the highlighted object and choose the Go To Connections for Duplicate Pairs from the context menu; all connection objects that share the same geometry pair will be highlighted. To search for connection objects that share the same geometry pair manually for one or more connection objects, select Search Connections for Duplicate Pairs from the context menu of these connection objects (by highlighting these connection objects first). If this command is issued from a Connection Group folder, the search will be carried out for all connection objects under this folder. When this command is issued from the Connections folder, the search will be for the entire connection objects under this folder.

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Contact

Moving and Copying Connection Objects To move a connection object to another folder of the same connection type, drag the object and drop it on that folder. For example, to move a contact region object, drag the object from its current Contacts folder and drop it on another folder whose Connection Type is Contact (possibly named Contacts 2). To copy a connection object to another folder of the same connection type, hold the Ctrl key while performing the move procedure described above.

Treatment of Legacy Databases Supported connection objects from databases of previous versions of ANSYS Workbench will be grouped based on their types and migrated into Connection Group folders.

Contact The following topics are covered in this section: Contact Overview Contact Formulation Theory Contact Settings Supported Contact Types Setting Contact Conditions Manually Contact Ease of Use Features Contact in Rigid Dynamics Best Practices for Specifying Contact Conditions

Contact Overview Contact conditions are created when an assembly is imported into the application and it detects that two separate bodies (solid, surface, and line bodies) touch one another (they are mutually tangent). Bodies/surfaces in contact: • Do not “interpenetrate.” • Can transmit compressive normal forces and tangential friction forces. • Can be bonded together (Linear) • Able to separate and collide (Nonlinear) Surfaces that are free to separate and move away from one another are said to have changing-status nonlinearity. That is, the stiffness of the system depends on the contact status, whether parts are touching or separated. Use the Contact Tool to help you coordinate contact conditions before loading and as part of the final solution.

Note For information about controlling the quality of facets, see Facet Quality in the Graphics section of the ANSYS DesignModeler help.

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Contact Formulation Theory Contact solutions are often very complicated. It is recommended that, whenever possible, that user employ the Program Controlled settings. However, in order to better understand your selections, this section examines the specifics of Formulations. Because physical contacting bodies do not interpenetrate, the application must establish a relationship between the two surfaces to prevent them from passing through each other in the analysis. When the application prevents interpenetration, it is said to enforce “contact compatibility”.

In order to enforce compatibility at the contact interface, Workbench Mechanical offers several different contact Formulations. These Formulations define the solution method used. Formulations include the following and are discussed in detail in the Formulations section. • Pure Penalty (Default - Program Controlled) • Augmented Lagrange • MPC • Normal Lagrange For nonlinear solid body contact of faces, Pure Penalty or Augmented Lagrange formulations can be used. Both of these are penalty-based contact formulations: FNormal = kNormalxPenetration The finite contact Force, Fn, is a concept of contact stiffness, kNormal. The higher the contact stiffness, the lower the penetration, xp, as illustrated here.

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Contact Ideally, for an infinite kNormal, one would get zero penetration. This is not numerically possible with penalty-based methods, but as long as xp is small or negligible, the solution results are accurate. The main difference between Pure Penalty and Augmented Lagrange methods is that Augmented Lagrange augments the contact force (pressure) calculations: Pure Penalty: FNormal = kNormalxPenetration Augmented Lagrange: FNormal = kNormalxPenetration + λ Because of the extra term λ, the Augmented Lagrange method is less sensitive to the magnitude of the contact stiffness kNormal. Another available option is Normal Lagrange. This formulation adds an extra degree of freedom (contact pressure) to satisfy contact compatibility. Consequently, instead of resolving contact force as contact stiffness and penetration, contact force (contact pressure) is solved for explicitly as an extra DOF. FNormal = DOF Specifications: • Enforces zero/nearly zero penetration with pressure DOF. • Does not require a normal contact stiffness (zero elastic slip) • Requires Direct Solver, which can increase computation requirements. Normal Lagrange Chattering Chattering is an issue which often occurs with Normal Lagrange method. If no penetration is allowed (left), then the contact status is either open or closed (a step function). This can sometimes make convergence more difficult because contact points may oscillate between open/closed status and is called "chattering". If some slight penetration is allowed (right), it can make it easier to converge since contact is no longer a step change.

For the specific case of Bonded and No Separation Types of contact between two faces, a Multi-Point constraint (MPC) formulation is available. MPC internally adds constraint equations to “tie” the displacements between contacting surfaces. This approach is not penalty-based or Lagrange multiplier-based. It is a direct, efficient way of relating surfaces of contact regions which are bonded. Large-deformation effects are supported with MPC-based Bonded contact.

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Comparison of Formulations Some of the primary aspects of contact formulations are compared below. Pure Penalty

Augmented Lagrange

Normal Lagrange

Good convergence beha- Additional equilibrium iter- Additional equilibrium vior (few equilibrium iter- ations needed if penetraiterations if needed ations). tion is too large. chattering is present. Sensitive to selection of normal contact stiffness.

Less sensitive to selection of normal contact stiffness.

Contact penetration is present and uncontrolled.

Contact penetration is present but controlled to some degree.

Good convergence behavior (few equilibrium iterations).

No normal contact stiffness is required. Usually, penetration is near-zero.

No Penetration. Only Bonded & No Separation behaviors.

Useful for any type of contact behavior. Iterative or Direct Solvers can be used.

MPC

Only Direct Solver can be Used.

Iterative or Direct Solvers can be used.

Symmetric or Asymmetric contact available.

Asymmetric contact Only

Contact detection at integration points.

Contact Detection at Nodes.

Contact Settings When a model is imported into Workbench Mechanical, the default setting of the application automatically detects instances where two bodies are in contact and generates corresponding Contact Region objects in the Tree Outline. When a Contact Region is selected in the Tree Outline, as illustrated here, contact settings are available in the Details view, and are included in the following categories: • Scope: settings for displaying, selecting, or listing contact and target geometries. • Definition: commonly used contact settings. • Advanced: advanced controls that are primarily program controlled. • Geometric Modification: settings for further defining contact interface behaviors.

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Contact

Scope Settings The properties for the Scope category are described in the following table. Property

Description/Selections

Scoping Method

Specifies whether the Contact Region is applied to a Geometry Selection (default), a Named Selection, or to a Pre-Generated Interface for fracture mechanics (Interface Delamination) when you are using the ANSYS Composite PrepPost (ACP) application.

Interface

This property displays when you select Pre-Generated Interface as the Scoping Method. It provides a drop-down list of the available interface layers that were imported from ACP.

Contact

Displays/selects which geometries (faces, edges, or vertices) are considered as contact. The geometries can be manually selected or automatically generated. For a Face/Edge contact, the edge must be designated as Contact. A contact pair can have a flexible-rigid scoping, but the flexible side of the pair must always be the Contact side. If the Contact side of the contact pair is scoped to multiple bodies, all of the bodies must have the same Stiffness Behavior, either Rigid or Flexible.

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Description/Selections Note that if you click on this field, the bodies are highlighted.

Target

Displays which body element (face or edge) is considered Target (versus Contact). This element can be manually set or automatically generated. For Face/Edge contact, the face must be designated as Target. If the Contact side of the contact pair has a flexible Stiffness Behavior then the Target side can be rigid. Multiple rigid bodies cannot be selected for the Target side scoping of the contact pair. The selection of multiple rigid bodies for the Target invalidates the Contact Region object and an error message is generated following the solution process. Note that if you click on this field, the bodies are highlighted.

Contact Bodies

This read only property displays which bodies have faces or edges in the Contact list.

Target Bodies

This read only property displays which bodies have faces or edges in the Target list.

Contact Shell Face

Specifies whether the Contact should be applied on a surface body’s top face or bottom face. If you set Contact Shell Face to the default option, Program Controlled, then the Target Shell Face option must also be set to Program Controlled. The Program Controlled default option is not valid for nonlinear contact types. This option displays only when you scope a surface body to Contact Bodies.

Target Shell Face

Specifies whether the Target should be applied on a surface body’s top face or bottom face. If you set Target Shell Face to the default option, Program Controlled, then the Contact Shell Face option must also be set to Program Controlled. The Program Controlled default option is not valid for nonlinear contact types. This option displays only when you scope a surface body to Target Bodies.

Shell Thickness Effect (See Using KEYOPT(11))

This property appears when the scoping of the contact or target includes a surface body. Options include: • Yes - indicates to include the property. • No (default) - indicates to exclude the property. When set to Yes, the contact object becomes under-defined if the Offset Type of any scoped surface body is set to a value other than Middle, In this situation, the following error message will be displayed: "The shell thickness effect of a contact pair is turned on; however, the offset type of a shell body in contact is set to other than Middle. Please set its offset type to Middle." In the presence of a Thickness, Imported Thickness, Layered Section, or an Imported Layered Section object, the following warning message will be issued if a solve is requested: "The shell thickness effect of a contact pair is turned on. Please make sure that the offset

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Contact Property

Description/Selections type of the thickness, imported thickness, layered sections and imported layered sections objects associated with the shell bodies in contact are set to Middle."

Shell Thickness Effect The Shell Thickness Effect allows users to automatically include the thickness of the surface body during contact calculations. Instead of contact being detected on the face of the surface body, contact will be detected a distance of half the thickness away from the face. If the surface body undergoes large strains and changes thickness, the updated (current) thickness is also used in the contact calculations. However, to be able to take advantage of this feature, the Offset Type must be set to Middle. For cases where the user has set Offset Type to Top or Bottom, the user can do the following: • For a given contact region, if contact is occurring on the same face (Top or Bottom) as the offset, no special settings are required. The location of the nodes and elements of the surface body represent the actual position of that face. • For Rough, Frictionless, or Frictional contact types, if contact is occurring on the opposite face as the offset, specify a contact Offset equal to the shell thickness for the Interface Treatment. Note that changes in shell thickness for large strain analyses will not be considered.

Note If the Shell Thickness Effect is activated and the user has specified a contact Offset for the Interface Treatment, the total offset will be half the thickness of the surface body plus the defined contact offset. Postprocessing surface bodies with the shell thickness effect has the following special considerations: • Because contact is detected half of the thickness from the middle of the surface body, viewing surface body results without Thick Shell and Beam (See Main Menu>View Menu) effects turned on will show an apparent gap between contact bodies. This is normal since contact is being detected away from the location of the nodes and elements. • When using the Contact Tool to postprocess penetration or gaps, these values are measured from the middle of the surface bodies (location of the nodes and elements), regardless of whether or not the shell thickness effect is active.

Support Specifications Note • All bodies selected for the Target or Contact side of a contact pair must have the same stiffness behavior. • You cannot scope the target side in a contact pair to more than one rigid body.

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Setting Connections • If any of the bodies you scope have rigid stiffness behavior, you must select Asymmetric behavior under Definition in the Details view. • If you have both rigid and flexible bodies in your contact pair, you must scope the rigid body as a Target.

Definition Settings The differences in the contact settings determine how the contacting bodies can move relative to one another. This category provides the following properties. • Type • Scope Mode • Behavior • Trim Contact • Suppressed

Type Choosing the appropriate contact type depends on the type of problem you are trying to solve. If modeling the ability of bodies to separate or open slightly is important and/or obtaining the stresses very near a contact interface is important, consider using one of the nonlinear contact types (Frictionless, Rough, Frictional), which can model gaps and more accurately model the true area of contact. However, using these contact types usually results in longer solution times and can have possible convergence problems due to the contact nonlinearity. If convergence problems arise or if determining the exact area of contact is critical, consider using a finer mesh (using the Sizing control) on the contact faces or edges. The available contact types are listed below. Most of the types apply to Contact Regions made up of faces only.

• Bonded: This is the default configuration and applies to all contact regions (surfaces, solids, lines, faces, edges). If contact regions are bonded, then no sliding or separation between faces or edges is allowed. Think of the region as glued. This type of contact allows for a linear solution since the contact length/area will not change during the application of the load. If contact is determined on the mathematical model, any gaps will be closed and any initial penetration will be ignored. [Not supported for Rigid Dynamics. Fixed joint can be used instead.]

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Contact • No Separation: This contact setting is similar to the Bonded case. It only applies to regions of faces (for 3D solids) or edges (for 2D plates). Separation of the geometries in contact is not allowed. • Frictionless: This setting models standard unilateral contact; that is, normal pressure equals zero if separation occurs. Thus gaps can form in the model between bodies depending on the loading. This solution is nonlinear because the area of contact may change as the load is applied. A zero coefficient of friction is assumed, thus allowing free sliding. The model should be well constrained when using this contact setting. Weak springs are added to the assembly to help stabilize the model in order to achieve a reasonable solution. • Rough: Similar to the frictionless setting, this setting models perfectly rough frictional contact where there is no sliding. It only applies to regions of faces (for 3D solids) or edges (for 2D plates). By default, no automatic closing of gaps is performed. This case corresponds to an infinite friction coefficient between the contacting bodies. [Not supported for Explicit Dynamics analyses.] • Frictional: In this setting, the two contacting geometries can carry shear stresses up to a certain magnitude across their interface before they start sliding relative to each other. This state is known as "sticking." The model defines an equivalent shear stress at which sliding on the geometry begins as a fraction of the contact pressure. Once the shear stress is exceeded, the two geometries will slide relative to each other. The coefficient of friction can be any nonnegative value. [Not supported for Rigid Dynamics. Forced Frictional Sliding should be used instead.] • Forced Frictional Sliding: In this setting, a tangent resisting force is applied at each contact point. The tangent force is proportional to the normal contact force. This settings is similar to Frictional except that there is no "sticking" state. [Supported only for Rigid Dynamics] By default the friction is not applied during collision. Collisions are treated as if the contact is frictionless regardless the friction coefficient. The following commands override this behavior and include friction in shock resolution (see Rigid Dynamics Command Objects Library in the ANSYS Mechanical User's Guide for more information). options=CS_SolverOptions() options.FrictionForShock=1 Note that shock resolution assumes permanent sliding during shock, which may lead to unrealistic results when the friction coefficient is greater than 0.5. • Friction Coefficient: Allows you to enter a friction coefficient. Displayed only for frictional contact applications.

Note • For the Bonded and No Separation contact Type, you can simulate the separation of a Contact Region as it reaches some predefined opening criteria using the Contact Debonding feature. • Refer to KEYOPT(12) in the Mechanical APDL Contact Technology Guide for more information about modelling different contact surface behaviors.

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Scope Mode This is a read-only property that displays how the selected Contact Region was generated. Either automatically generated by the application (Automatic) or constructed or modified by the user (Manual). Note that this property is not supported for Rigid Body Dynamics analyses.

Behavior This property will appear only for 3D Face/Face or 2D Edge/Edge contacts. For 3D Edge/Edge or Face/Edge contacts, internally the program will set the contact behavior to Asymmetric (see below). Note that this property is not supported for Rigid Body Dynamics analyses.

Sets contact pair to one of the following: • Program Controlled (Default for the Mechanical APDL solver): internally the contact behavior is set to the following options based on the stated condition: – Auto Asymmetric (see below) - for Flexible-Flexible bodies. – Asymmetric (see below) - for Flexible-Rigid bodies. For Rigid-Rigid contacts, the Behavior property is under-defined for the Program Controlled setting. The validation check is performed at the Contact object level when all environment branches are using the Mechanical APDL solver. If the solver target for one of the environments is other than Mechanical APDL, then this validation check will be carried out at the environment level; the environment branch will become under-defined. • Asymmetric: Contact will be asymmetric for the solve. All face/edge and edge/edge contacts will be asymmetric. [Not supported for Explicit Dynamics analyses.] Asymmetric contact has one face as Contact and one face as Target (as defined under Scope Settings), creating a single contact pair. This is sometimes called "one-pass contact," and is usually the most efficient way to model face-to-face contact for solid bodies. The Behavior must be Asymmetric if the scoping includes a body specified with rigid Stiffness Behavior. • Symmetric: Contact will be symmetric for the solve. • Auto Asymmetric: Automatically creates an asymmetric (p. 512) contact pair, if possible. This can significantly improve performance in some instances. When you choose this setting, during the solution phase the

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Contact solver will automatically choose the more appropriate contact face designation. Of course, you can designate the roles of each face in the contact pair manually. [Not supported for Explicit Dynamics analyses.]

Note Refer to KEYOPT(8) in the Mechanical APDL Contact Technology Guide for more information about asymmetric contact selection.

Trim Contact The Trim Contact feature can speed up the solution time by reducing the number of contact elements sent to the solver for consideration. Note that this feature is not supported for Rigid Body Dynamics analyses.

Trim Contact options include: • Program Controlled: This is the default setting. The application chooses the appropriate setting. Typically, the program sets Trim Contact to On. However, if there are manually created contact conditions, no trimming is performed. • On: During the process of creating the solver input file, checking is performed to determine the proximity between source and target elements. Elements from the source and target sides which are not in close proximity (determined by a tolerance) are not written to the file and therefore ignored in the analysis. • Off: No contact trimming is performed. The checking process is performed to identify if there is overlap between the bounding boxes of the elements involved. If the bounding box of an element does not overlap the bounding box of an opposing face or element set, that element is excluded from the solution. Before the elements are checked, the bounding boxes are expanded using the Trim Tolerance property (explained below) so that overlapping can be detected. Trim Tolerance This property provides the ability to define the tolerance value that is used to expand the bounding boxes of the elements before the trimming process is performed. This property is available for both automatic and manual contacts when the Trim Contact is set to On. It is only available for automatic contacts when the Trim Contact is set to Program Controlled since no trimming is performed for manual contacts. For automatic contacts, this property displays the value that was used for contact detection and it is a read-only field. For manual contacts, enter a value greater than zero.

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Setting Connections Note that a doubling expansion effect can result from the bounding box expansion since the bounding box of both the source and target elements are expanded. An example of the double expansion effect is illustrated below where the Trim Tolerance is defined as 10 mm. For simplicity sake, the size of the elements is specified as 5mm. Therefore, the bounding boxes for the contact/target elements will extend 10mm (two elements) in each direction as represented by the orange boxes, solid and dashed. For each face, Contact and Target, the number of elements that will be used are illustrated.

The brown area illustrated below represents the elements from the contact face. On the corresponding target side exist potential elements from the entire target face. The elements of the target face that will be kept are drawn in black. On the target Face, each element bounding box is expanded by 10mm and an overlap is sought against each element from the contact side. Referring to the image below, the bounding boxes between Contact Element 1 (CE1) and Target Element 2 (TE2) overlap thus TE2 is included in the analysis. Meanwhile, CE3 and TE4 do not overlap and as a result, TE4 is not included in the analysis. This results in a reduced number of elements in the analysis and, typically, a faster solution.

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Contact

Suppressed Specifies whether or not the Contact Region is included in the solution.

Advanced Settings The Advanced category provides the following properties. • Formulation • Detection Method • Penetration Tolerance • Elastic Slip Tolerance • Normal Stiffness • Constraint Type • Update Stiffness • Stabilization Damping Factor • Thermal Conductance • Pinball Region

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Setting Connections • Pinball Radius • Electric Conductance • Restitution Factor - Rigid Body Dynamics Solver Only

Formulation Formulation options allow you to specify which algorithm the software uses for a particular Contact pair computation. Property options include:

Property

Description

Program Controlled

This is the default setting. For this setting, the application selects the Pure Penalty property for contact between two rigid bodies and the Augmented Lagrange property for all other contact situations.

Pure Penalty

Basic contact formulation based on Penalty method.

Augmented Lagrange

Also a penalty-based method. Compared to the Pure Penalty method, this method usually leads to better conditioning and is less sensitive KEYto the magnitude of the contact stiffness coefficient. However, in OPT(2) some analyses, the Augmented Lagrange method may require addi=0 tional iterations, especially if the deformed mesh becomes too distorted.

MPC

Available for Bonded and for No Separation contact Types. Multipoint Constraint equations are created internally during the Mechanical APDL application solve to tie the bodies together. This can be helpful if truly linear contact is desired or to handle the nonzero mode issue for free vibration that can occur if a penalty function is used. Note that contact based results (such as pressure) will be zero.

Note When modeling Shell-Solid assemblies with the MPC contact Formulation, the contact surface/edge must be on the shell side and the target surface must be on the solid side. However, you can override this requirement to support certain special cases, such as acoustics. Please see the Modeling a Shell-Solid As-

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MAPDL KEYOPT(2) =1

KEYOPT(2) =2

Contact sembly section of the Mechanical APDL Contact Technology Guide for additional information. Normal Lagrange

Enforces zero penetration when contact is closed making use of a Lagrange multiplier on the normal direction and a penalty method in the tangential direction. Normal Stiffness is not applicable for this KEYsetting. Normal Lagrange adds contact traction to the model as addiOPT(2) tional degrees of freedom and requires additional iterations to stabilize =3 contact conditions. It often increases the computational cost compared to the Augmented Lagrange setting. The Iterative setting (under Solver Type) cannot be used with this method.

For additional MAPDL specific information, see KEYOPT(2) in the Mechanical APDL Contact Technology Guide.

Note Cases involving large gaps and faces bonded together can result in fictitious moments being transmitted across a boundary.

Detection Method Detection Method allows you to choose the location of contact detection used in the analysis in order to obtain a good convergence. It is applicable to 3D face-face contacts and 2D edge-edge contacts. Property options include:

Property

Description

Program Controlled

This is the default setting. The application uses Gauss integration points (On Gauss Point) when the formulation is set to Pure Penalty and Augmented Lagrange. It uses nodal point (Nodal-Normal to Target) for MPC and Normal Lagrange formulations.

On Gauss Point

The contact detection location is at the Gauss integration points. This option is not applicable to contacts with MPC or Normal Lagrange formulation.

Nodal - Normal From Contact

The contact detection location is on a nodal point where the contact normal is perpendicular to the contact surface.

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Setting Connections Nodal - Normal To Target

The contact detection location is on a nodal point where the contact normal is perpendicular to the target surface.

Nodal - Projected Normal From Contact

The contact detection location is at contact nodal points in an overlapping region of the contact and target surfaces (projection-based method).

For additional MAPDL specific information, see Selecting Location of Contact Detection (specifically, KEYOPT(4) related information) in the Mechanical APDL Contact Technology Guide.

Penetration Tolerance The Penetration Tolerance property allows you to specify the Penetration Tolerance Value or the Penetration Tolerance Factor for a contact when the Formulation property is set to Program Controlled, Pure Penalty, or Augmented Lagrange.

Note The Update Stiffness property must be set to either Program Controlled, Each Iteration, or Each Iteration, Aggressive for the Penetration Tolerance property to be displayed when Formulation is set to Pure Penalty. Property options include:

Property

Description

Program Controlled

This is the default setting. The Penetration Tolerance is calculated by the program.

Value

Enter the Penetration Tolerance Value directly. This entry is a length measurement (foot, meter, etc.). Only non-zero positive values are valid.

Factor

Enter the Penetration Tolerance Factor directly. This entry must be equal to or greater than zero but must also be less than 1.0. This entry has no unit.

Penetration Tolerance Value The Penetration Tolerance Value property displays when Penetration Tolerance is set to Value. You enter a Value. Penetration Tolerance Factor

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Contact The Penetration Tolerance Factor property displays when Penetration Tolerance is set to Factor. You enter a Factor.

Note When viewing the Connections Worksheet, a Value displays as a negative number and a Factor displays as a positive number. For additional information, see the Determining Contact Stiffness and Allowable Penetration, specifically Using FKN and FTOLN, section of the Mechanical APDL Contact Technology Guide (Surface-to-Surface Contact).

Elastic Slip Tolerance The Elastic Slip Tolerance property allows you to set the allowable elastic slip value for a contact when the Formulation is set to Normal Lagrange or when the contact stiffness is set to update each iteration (Update Stiffness is set to Each Iteration or Each Iteration, Aggressive).

Note Elastic Slip Tolerance is not applicable when the contact Type is set to Frictionless or No Separation. Property options include:

Property

Description

Program Controlled

This is the default setting. The Elastic Slip Tolerance Value is calculated by the application.

Value

Enter the Elastic Slip Tolerance Value directly. This entry is a length measurement (foot, meter, etc.). Only non-zero positive values are valid.

Factor

Enter the Elastic Slip Tolerance Factor directly. This entry must be equal to or greater than zero but must also be less than 1.0. This entry has no unit.

Elastic Slip Tolerance Value The Elastic Slip Tolerance Value property displays when Elastic Slip Tolerance is set to Value. You enter a Value. Elastic Slip Tolerance Factor Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Setting Connections The Elastic Slip Tolerance Factor property displays when Elastic Slip Tolerance is set to Factor. You enter a Factor.

Note When viewing the Connections Worksheet, a Value displays as a negative number and a Factor displays as a positive number. For additional information, see the Determining Contact Stiffness and Allowable Penetration, specifically Using FKT and SLTO, section of the Mechanical APDL Contact Technology Guide (Surface-to-Surface Contact).

Constraint Type Controls the type of MPC constraint to be created for bonded contact. This setting is displayed only if Formulation is set to MPC and if either Contact Bodies or Target Bodies are scoped to a surface body. Property options include:

Property

Description

Target Normal, Couple U to ROT

This is the default setting. Represents the most common type of surface body contact. Constraints are constructed to couple the translational and rotational DOFs. In most types of surface body contact, an offset will exist. Due to this offset there will be a moment created. To get the correct moment, the rotation/displacement DOF's must be coupled together. If the program cannot detect any contact in the target normal direction, it will then search anywhere inside the pinball for contact.

Target Normal, Uncouple U to ROT

The rotational and displacement constraints will not be coupled together. This option can model situations where the surface body edges line up well and a moment is not created from the physical surface body positions. Thus it is most accurate for the constraints to leave the displacements/rotations uncoupled. This provides an answer which is closer to a matching mesh solution. Using a coupled constraint causes artificial constraints to be added causing an inaccurate solution.

Inside Pinball, Couple U to ROT

Constraints are coupled and created anywhere to be found inside the pinball region. Thus the pinball size is important as a larger pinball will result in a larger constraint set. This option is useful when you wish to fully constrain one contact side completely to another.

Normal Stiffness Defines a contact Normal Stiffness factor. Property options include:

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Contact Option

Description

Program Controlled

This is the default setting. The Normal Stiffness Factor is calculated by the program. If only Bonded or No Separation contact exists, the value is set to 10. If any other type of contact exists, all the program controlled regions (including Bonded or No Separation) will use the Mechanical APDL application default (Real Constant FKN).

Manual

The Normal Stiffness Factor is input directly by the user.

Normal Stiffness Factor This property appears when the Normal Stiffness is set to Manual. It allows you to input the Normal Stiffness Factor. Only non-zero positive values are allowed. The usual factor range is from 0.01-10, with the default selected programmatically. A smaller value provides for easier convergence but with more penetration. The default value is appropriate for bulk deformation. If bending deformation dominates, use a smaller value (0.01-0.1). For additional MAPDL specific information, see the • Determining Contact Stiffness and Allowable Penetration section of the Mechanical APDL Contact Technology Guide (Surface-to-Surface Contact). • Using FKN and FTOLN section of the Mechanical APDL Contact Technology Guide (Surface-to-Surface Contact).

Update Stiffness Allows you to specify if the program should update (change) the contact stiffness during the solution. If you choose any of these stiffness update settings, the program will modify the stiffness (raise/lower/leave unchanged) based on the physics of the model (that is, the underlying element stress and penetration). This choice is displayed only if you set the Formulation to Augmented Lagrange or Pure Penalty, the two formulations where contact stiffness is applicable. An advantage of choosing either of the program stiffness update settings is that stiffness is automatically determined that allows both convergence and minimal penetration. Also, if this setting is used, problems may converge in a Newton-Raphson sense, that would not otherwise. You can use a Result Tracker to monitor a changing contact stiffness throughout the solution. Property options include:

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Setting Connections Property

Description

Program Controlled

(Default as set in Tools->Options). Internally set based on the following criteria: if the Interface Treatment property is available and it is set to Add Offset, Ramped Effects, the update stiffness property should be set to Never; otherwise, set the update stiffness property to Never for contacts between two rigid bodies and to Each Iteration for others.

Never

This is the default setting. Turns off the program's automatic Update Stiffness feature.

Each Iteration

Sets the program to update stiffness at the end of each equilibrium iteration. This choice is recommended if you are unsure of a Normal Stiffness Factor to use in order to obtain good results.

Each Iteration, Aggressive

Sets the program to update stiffness at the end of each equilibrium iteration, but compared to the Each Iteration, this option allows for a more aggressive changing of the value range.

Stabilization Damping Factor A contact you define may initially have a near open status due to small gaps between the element meshes or between the integration points of the contact and target elements. The contact will not get detected during the analysis and can cause a rigid body motion of the bodies defined in the contact. The stabilization damping factor provides a certain resistance to damp the relative motion between the contacting surfaces and prevents rigid body motion. This contact damping factor is applied in the contact normal direction and it is valid only for frictionless, rough and frictional contacts. The damping is applied to each load step where the contact status is open. The value of the stabilization damping factor should be large enough to prevent rigid body motion but small enough to ensure a solution. A value of 1 is usually appropriate. Property options include: Property Stabilization Damping Factor

Description

MAPDL

If this factor is 0 (default), the damping is activated only in the first load step (KEYOPT(15) = 0, the default). If its value is greater than 0, the damping is activated for all load steps (KEYOPT(15) = 2).

FDMN

Damping is activated for all load steps.

Thermal Conductance Controls the thermal contact conductance value used in a thermal contact simulation. Property options include: Property

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KEYOPT(15) = 2.

Description

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Contact Program Controlled

This is the default setting. The program will calculate the value for the thermal contact conductance. The value will be set to a sufficiently high enough value (based on the thermal conductivities and the model size) to model perfect contact with minimal thermal resistance.

Manual

The Thermal Conductance Value is input directly by the user.

Thermal Conductance Value Allows input of the Thermal Conductance Value. Only positive values are allowed. This choice is displayed only if Manual is specified for Thermal Conductance. The Units for this value are based on the types of contact involved. For 3D faces and 2D edges, the units are HEAT/(TIME * TEMPERATURE* AREA). For contact between 3D edges and vertices, the units are HEAT/(TIME * TEMPERATURE) with the value applied to every node in the contact side. For more information about the units used for thermal contact conductance coefficient, see Table 78 and Table 79 in the Solving Units section. For additional MAPDL specific information, see the Modeling Thermal Contact, specifically Modeling Conduction>Using TCC, section of the Mechanical APDL Contact Technology Guide (Multiphysics Contact).

Pinball Region This option allows you to specify the contact search size, commonly referred to as the Pinball Region. Setting a pinball region can be useful in cases where initially, bodies are far enough away from one another that, by default, the program will not detect that they are in contact. You could then increase the pinball region as needed. Consider an example of a surface body that was generated by offsetting a face of a solid body, possibly leaving a large gap, depending on the thickness. Another example is a large deflection problem where a considerable pinball region is required due to possible large amounts of over penetration. In general though, if you want two regions to be bonded together that may be far apart, you should specify a pinball region that is large enough to ensure that contact indeed occurs. For bonded and no separation contact types, you must be careful in specifying a large pinball region. For these types of contact, any regions found within the pinball region will be considered to be in contact. For other types of contact, this is not as critical because additional calculations are performed to determine if the two bodies are truly in contact. The pinball region defines the searching range where these calculations will occur. Further, a large gap can transmit fictitious moments across the boundary. Property options include: Property

Description

Program Controlled

This is the default setting. The pinball region will be calculated by the program.

Auto Detection Value

This option is only available for contacts generated automatically. The pinball region will be equal to the tolerance value used in generating the contacts. The value is displayed as read-only in the Auto Detection Value field. Auto Detection Value is the recommended option for cases where the automatic contact detection region is larger than a Program Controlled region. In such cases, some contact pairs that were detected automatically may not be considered in contact for a solution.

Radius

The radius value is input directly by the user.

For the Rigid Body Dynamics solver: In the Rigid Body Dynamics solver, the pinball region is used to control the touching tolerance. By default, the Rigid Body Dynamics solver automatically computes the touching tolerance using the sizes of the surfaces in the contact region. These default values are sufficient in most of cases, but inadequate touching tolerance may arise in cases where contact surfaces Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Setting Connections are especially large or small (small fillet for instance). In such cases, the value of the touching tolerance can be directly specified using the following properties: Property

Description

Program Controlled (default)

The touching tolerance is automatically computed by the Rigid Body Dynamics solver from the sizes of the contact surfaces.

Radius

The value of the touching tolerance is directly given by user.

Pinball Radius The numerical value for the Pinball Radius. This choice is displayed only if Pinball Region is set to Radius.

Electric Conductance Controls the electric contact conductance value used in an electric contact simulation. Property options include: Property

Description

Program Controlled

This is the default setting. The program will calculate the value for the electric contact conductance. The value will be set to a sufficiently high enough value (based on the electric conductivities and the model size) to model perfect contact with minimal electric resistance.

Manual

The Electric Conductance Value is input directly by the user.

Note The Electric Analysis result, Joule Heat, when generated by nonzero contact resistance is not supported.

Electric Conductance Value Allows input of the Electric Conductance Value (in units of electric conductance per area). Only positive values are allowed. This choice is displayed only if Manual is specified for Electric Conductance.

Time Step Controls Allows you to specify if changes in contact behavior should control automatic time stepping. This choice is displayed only for nonlinear contact (Type is set to Frictionless, Rough, or Frictional). Property options include: Property

Description

None

This is the default setting. Contact behavior does not control automatic time stepping. This option is appropriate for most analyses when automatic time stepping is activated and a small time step size is allowed.

Automatic Bisection

Contact behavior is reviewed at the end of each substep to determine whether excessive penetration or drastic changes in contact status have occurred. If so,

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Contact the substep is reevaluated using a time increment that is bisected (reduced by half ). Predict for Impact

Performs same bisection on the basis of contact as the Automatic Bisection option and also predicts the minimal time increment needed to detect changes in contact behavior. This option is recommended if you anticipate impact in the analysis.

Restitution Factor - Rigid Body Dynamics Solver Only For the ANSYS Rigid Dynamics solver, the Advanced group has only one property, Restitution Value. This value represents the energy lost during shock and is defined as the ratio between relative velocity prior to the shock and the velocity following the shock. This value can be between 0 and 1. A Restitution Factor equal to 1 indicates that no energy is lost during the shock, that is, the rebounding velocity equals the impact velocity (a perfectly elastic collision). The default value is 1.

Geometric Modification The Geometric Modification category provides the properties described below. As described, this category only displays when certain contact conditions are detected by the application and/or certain property definitions are specified.

Interface Treatment The Interface Treatment property defines how the contact interface of a contact pair is treated. It becomes active when contact Type is set to Frictionless, Rough or Frictional (nonlinear contact). When active, the Interface Treatment option provides the following properties.

• Adjust to Touch: Any initial gaps are closed and any initial penetration is ignored creating an initial stress free state. Contact pairs are “just touching” as shown.

Contact pair before any Interface Treatment. Gap exists.

Contact pair after Adjust to Touch treatment. Gap is closed automatically. Pair is “just touching”.

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Setting Connections

Contact pair before any Interface Treatment. Penetration exists.

Contact pair after Adjust to Touch treatment. Pair touches at interface.

This setting is useful to make sure initial contact occurs even if any gaps are present (as long as they are within the pinball region). Without using this setting, the bodies may fly apart if any initial gaps exist. Although any initial gaps are ignored, gaps can still form during loading for the nonlinear contact types. For nonlinear contact types (Frictionless, Rough, and Frictional), Interface Treatment is displayed where the choices are Adjust to Touch, Add Offset, Ramped Effects, and Add Offset, No Ramping. • Add Offset, Ramped Effects: models the true contact gap/penetration plus adds in any user defined offset values. This setting is the closest to the default contact setting used in the Mechanical APDL application except that the loading is ramped. Using this setting will not close gaps. Even a slight gap may cause bodies to fly apart. Should this occur, use a small contact offset to bring the bodies into initial contact. Note that this setting is displayed only for nonlinear contact. • Add Offset, No Ramping: this is the default setting. This option is the same as Add Offset, Ramped Effects but loading is not ramped. • Offset: appears if Interface Treatment is set to Add Offset, Ramped or Add Offset, No Ramping. This property defines the contact offset value. A positive value moves the contact closer together (increase penetration/reduce gap) and a negative value moves the contact further apart.

Contact pair before any Interface Treatment. Gap exists.

Contact pair after Add Offset treatment (either option). Gap is closed "manually” based on value entered for Offset (positive value shown that includes some penetration).

Contact Geometry Correction When specified as Bolt Thread (the default is None), the Contact Geometry Correction property activates the properties shown below.

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Contact For 2D axisymmetric models, only edge-to-edge scoping is supported and for 3D models, only face-toface scoping is supported. For additional information about this property, please see the Simplified Bolt Thread Modeling section of the Mechanical APDL Contact Technology Guide.

Tip When you specify the Bolt Thread option, it is strongly recommended that you have a refined mesh. Please see the Relevance and the Sizing Group (Category) sections of the Meshing User's Guide for additional information about mesh refinement. Support Requirements In order to use the Bolt Thread option, please note the following. • The Contact Geometry Correction property is available for all contact Type settings except for Bonded. • The Behavior properties Symmetric and Auto-Asymmetric are not supported. • It is recommended that you do not set the Detection Method to either Nodal-Normal To Target or On Gauss Point.

Bolt Thread Property The following properties are visible when Contact Geometry Correction is set to Bolt Thread. Orientation Property options include: • Program Controlled (default): A contact condition with Contact Geometry Correction defined as Bolt Thread, is fully defined only when cylindrical contact conditions are detected by the application, otherwise, manual specifications are required. • Revolute Axis: when Revolute Axis is selected, the following additional properties display. These properties define the coordinate systems that are used to generate the axis around which the bolt is oriented. They do not correspond to the starting and ending point of the bolt threads. – Starting Point – Ending Point

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Setting Connections Mean Pitch Diameter This property defines the average diameter of the threaded bolt. Pitch Distance This property defines the length of the thread pitch. Thread Angle This property defines the angle of the thread’s inclination. The following diagram illustrates the Mean Pitch Diameter, Pitch Distance, and Thread Angle.

Thread Type This property defines the number of threads on the bolt. Property options include: • Single-Thread • Double-Thread • Triple-Thread Handedness This property defines the bolt as either right or left handed. Property options include: • Right-Handed • Left-Handed

Supported Contact Types The following table identifies the supported formulations and whether symmetry is respected for the various contact geometries. Contact Geometry

Face

Edge

(Scope = Contact)

(Scope = Contact)

Vertex (Line Bodies Only) (Scope = Contact)

Face (Scope = Target)

Symmetry Respected: Yes

Edge[1] (p. 529) Not Supported for solving.

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Symmetry Respected: No

Symmetry Respected: No

Symmetry Respected: No

Symmetry Respected: No

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Contact (Scope = Target) Vertex (Scope = Target)

Not Supported for solving.

Not Supported for solving.

Not Supported for solving.

[1]: The underlying body cannot be a line body. In 2D analyses, only edge-edge contact is supported (the equivalent of 3D face-face contact).

Setting Contact Conditions Manually Manual contact regions represent contact over the entire extent of the contact scope, for example, faces of the contact region. Automatic contact regions represent contact only to the extent of the scope where the corresponding bodies initially are close to one another. For automatic contact, the contact elements are “trimmed” before solution. The trimming is based on the detection tolerance. The tighter the tolerance, the less number of generated contact elements. Note that if you set Large Deflection effects to On in the Details view of a Solution object, no trimming will be done due to the possibility of large sliding. Valid reasons to manually change or add/delete contact regions include: • Modeling "large sliding" contact. Contact regions created through auto-detection assume "assembly contact," placing contact faces very near to one another. Manual contact encompasses the entire scope so sliding is better captured. In this case, you may need to add additional contact faces. • Auto-detection creates more contact pairs than are necessary. In this case, you can delete the unnecessary contact regions. • Auto-detection may not create contact regions necessary for your analysis. In this case, you must add additional contact regions. You can set contact conditions manually, rather than (or in addition to) letting the application automatically detect contact regions. Within a source or target region, the underlying geometry must be of the same geometry type (for example, all surface body faces, all solid body faces). The source and target can be of different geometry types, but within itself, a source must be of the same geometry type, and a target must be of the same geometry type. To set contact regions manually: 1.

Click the Connections object in the Tree Outline (p. 3).

2.

Click the right mouse button and choose Insert> Manual Contact Region. You can also select the Contact button on the toolbar.

3.

A Contact Region item appears in the Outline. Click that item, and under the Details View (p. 11), specify the Contact and Target regions (faces or edges) and the contact type. See the Contact and Target topics in the Scope Settings section for additional Contact Region scoping restrictions.

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Setting Connections

Contact Ease of Use Features The following features are intended to assist you in performing simulations involving contact: Controlling Transparency for Contact Regions Displaying Contact Bodies with Different Colors Displaying Contact Bodies in Separate Windows Hiding Bodies Not Scoped to a Contact Region Renaming Contact Regions Based on Geometry Names Identifying Contact Regions for a Body Create Contact Debonding Flipping Contact and Target Scope Settings Merging Contact Regions That Share Geometry Saving or Loading Contact Region Settings Resetting Contact Regions to Default Settings Locating Bodies Without Contact Locating Parts Without Contact

Controlling Transparency for Contact Regions As shown below, you can graphically highlight an individual contact region. The following demo is presented as an animated GIF. Please view online if you are reading the PDF version of the help. Interface names and other components shown in the demo may differ from those in the released product. • Click on a contact region to highlight the bodies in that region. • Highlighting is due to internal transparency settings: – Transparency is set to 0.8 for bodies in selected contact region. – Transparency is set to 0.1 for bodies not in selected contact region(s). – You can change the default transparency values in the Mechanical application Connections settings of the Options dialog box. • You can disable the contact region highlighting feature in either the Details view of a contact group branch, or by accessing the context menu (right mouse click) on a contact region or contact group branch of the tree, and choosing Disable Transparency.

Displaying Contact Bodies with Different Colors By default, contact bodies are all displayed using the same color. Use the Random Colors button in the Graphics Options toolbar to display each contact using a color chosen at random each redraw.

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Contact

Displaying Contact Bodies in Separate Windows Use the Body Views button on the Connections Context Toolbar to display parts in separate auxiliary windows. As illustrated and highlighted below, the different contact bodies (Contact and Target) have colors codes associated with them. In the Details as well as the graphic windows. Contact Bodies View

Target Bodies View

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Setting Connections

Hiding Bodies Not Scoped to a Contact Region You can hide all bodies except those that are scoped to a specific contact region. To Hide All Bodies Not Scoped to a Contact Region: 1.

Select the Contact Region object whose bodies you do not want to hide.

2.

Right-click to display the context menu.

3.

Select Hide All Other Bodies in the menu. All bodies are hidden except those that are part of the selected contact region.

Renaming Contact Regions Based on Geometry Names You can change the name of any contact region using the following choices available in the context menu that appears when you click the right mouse button on a particular contact region: • Rename: Allows you to change the contact region name to a name that you type (similar to renaming a file in Windows Explorer). • Rename Based on Definition: Allows you to change the contact region name to include the corresponding names of the items in the Geometry branch of the tree that make up the contact region. The items are separated by the word “To” in the new contact region name. You can change all the contact region names at once by clicking the right mouse button on the Connections branch, then choosing Rename Based on Definition from that context menu. A demonstration of this feature follows. The following demo is presented as an animated GIF. Please view online if you are reading the PDF version of the help. Interface names and other components shown in the demo may differ from those in the released product.

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Contact

When you change the names of contact regions that involve multiple bodies, the region names change to include the word Multiple instead of the long list of names associated with multiple bodies. An example is Bonded – Multiple To Multiple.

Identifying Contact Regions for a Body See the description for Contacts for Selected Bodies in the Correlating Tree Outline Objects with Model Characteristics (p. 6) section.

Create Contact Debonding To automatically generate a Contact Debonding object, select a Contact Region and drag and drop it onto the Fracture folder.

Flipping Contact and Target Scope Settings A valuable feature available when using asymmetric contact is the ability to swap contact and target face or edge Scope settings in the Details view. You accomplish this by clicking the right mouse button on the specific contact regions (Ctrl key or Shift key for multiple selections) and choosing Flip Contact/Target. This is illustrated below for a single region. The following demo is presented as an animated GIF. Please view online if you are reading the PDF version of the help. Interface names and other components shown in the demo may differ from those in the released product.

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Setting Connections

Note This feature is not applicable to Face/Edge contact where faces are always designated as targets and edges are always designated as contacts.

Merging Contact Regions That Share Geometry You can merge two or more contact regions into one contact region, provided they share the same type of geometry (edges or faces). To Merge Contact Regions That Share Geometry: 1.

Select two or more contact regions in the tree that share the same type of geometry (edges or faces). Use the Shift or Ctrl key for multiple selections.

2.

Right-click to display the context menu.

3.

Select Merge Selected Contact Regions in the menu. This option only appears if the regions share the same geometry types. After selecting the option, a new contact region is appended to the list in the tree. The new region represents the merged regions. The individual contact regions that you selected to form the merged region are no longer represented in the list.

Saving or Loading Contact Region Settings You can save the configuration settings of a contact region to an XML file. You can also load settings from an XML file to configure other contact regions. To Save Configuration Settings of a Contact Region: 1.

Select the contact region whose settings you want to save.

2.

Right-click to display the context menu.

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Contact 3.

Select Save Contact Region Settings in the menu. This option does not appear if you selected more than one contact region.

4.

Specify the name and destination of the file. An XML file is created that contains the configuration settings of the contact region.

Note The XML file contains properties that are universally applied to contact regions. For this reason, source and target geometries are not included in the file. To Load Configuration Settings to Contact Regions: 1.

Select the contact regions whose settings you want to assign. Use the Shift or Ctrl key for multiple selections.

2.

Right-click to display the context menu.

3.

Select Load Contact Region Settings in the menu.

4.

Specify the name and location of the XML file that contains the configuration settings of a contact region. Those settings are applied to the selected contact regions and will appear in the Details view of these regions.

Resetting Contact Regions to Default Settings You can reset the default configuration settings of selected contact regions. To Reset Default Configuration Settings of Contact Regions: 1.

Select the contact regions whose settings you want to reset to default values. Use the Shift or Ctrl key for multiple selections.

2.

Right-click to display the context menu.

3.

Select Reset to Default in the menu. Default settings are applied to the selected contact regions and will appear in the Details view of these regions.

Locating Bodies Without Contact See the description for Bodies Without Contacts in Tree in the Correlating Tree Outline Objects with Model Characteristics (p. 6) section.

Locating Parts Without Contact See the description for Parts Without Contacts in Tree in the Correlating Tree Outline Objects with Model Characteristics (p. 6) section.

Contact in Rigid Dynamics Contact conditions are formed where rigid bodies meet. While the default contact settings and automatic detection capabilities are often sufficient for structural analyses, the default contact definition

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Setting Connections must be extended to adjacent surfaces in some cases. This is because the nature of rigid dynamics usually implies very large displacements and rotations. In rigid dynamics, only frictionless and forced friction contact is supported. The contact is always based on Pure Lagrange formulation. Contact constraint equations are updated at each time step, and added to the system matrix through additional forces of degrees of freedom called Lagrange Multipliers. In this formulation, there is no contact stiffness. Contact constraints are satisfied when the bodies are touching, and they are nonexistent when bodies are separated. Contact and Rigid Bodies Contact is formulated between rigid bodies. Hence, there is no possibility of deforming the bodies to satisfy the contact constraint equations. If the contact equations cannot eventually be satisfied, the solution will not proceed. To illustrate this, two examples are considered: Example 3: Cylindrical Shaft in a Block

• If the diameter of the cylindrical shaft is smaller than that of the hole, motion is possible. • If the diameter of the cylindrical shaft is larger than that of the hole, the simulation is not possible. • If the two diameters are exactly equal, then the analysis might fail.

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Contact Example 4: Block Sliding on Two Blocks

• If the green block slides horizontally from left to right and the height of the right block is less than that of the left block, motion is possible. • If the height of the two bottom blocks is identical and a vertical contact surface is defined between the two bottom blocks, the block might hit the vertical surface, and the solution will not proceed. • If the height of the right block is greater than the height of the left block, the green block will move back to the left.

Note Avoid ambiguous configurations whenever possible. Consider creating fillets on sharp edges as a workaround. Contact Mesh You can scope the contact objects to rigid bodies using 3-D faces in solid bodies. When you create this type of contact, the surface and edges in the contact region are meshed. The mesh helps to speed up the solution by providing an initial position to the contact points that are calculated, and it helps to drive the number of contact points used between the bodies when in contact. As each body has up to 6 degrees of freedom, a contact between two rigid bodies will restrain up to 6 relative degrees of freedom. This means that a reasonably coarse mesh is generally sufficient to define the contact surface. The contact solver will use this mesh to initiate the contact geometry calculation, but will then project back the contact points to CAD geometry. Refining the mesh can increase the solution time without always increasing the quality of the solution. Conversely, refining the mesh can be useful if the geometry is concave and the solver reports a high amount of shocks for the pair involving the concave surfaces. Contact and Time Step The rigid solver uses event-based time integration. Over each time step, the solver evaluates the trajectory of the bodies, and checks when these trajectories interfere. When interference is found (as with stops on joints), a shock will be analyzed, leading to a new velocity distribution. The physics of the velocity redistribution during the shock is based on the conservation of momentum and energy. The amount of energy lost during the shock is quantified by the coefficient of restitution. For details see, Joint Stops and Locks. The trajectory detection of interferences allows the use of rather large time steps without missing the contacts; however, transitions between adjacent contact surfaces in certain situations (such as sliding situations) often require smaller time steps.

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Setting Connections In contrast to Penalty based simulation that introduces an artificial deformation of the bodies and thus high frequencies in the simulation, the pure Lagrange formulation used in the rigid dynamics formulation does not change the frequency content of the simulation. A solution that includes contact requires an increased amount of geometrical calculation, resulting in a significantly higher overall simulation time than a solution without contact. As such, it is recommended that joints stops are used in place of contacts whenever possible. Limitations For models with sliding contacts, e.g., cams, guiding grooves, etc., small bounces due to nonzero restitution factors can cause an increase in simulation time and instabilities. Using a restitution factor of zero will significantly speed up the simulation. The Rigid Dynamics solver unifies contact regions defined between the same pairs of parts/bodies. Consequently, defining more than one contact region between the same pairs of bodies may lead to unpredictable results. The following guidelines are strongly recommended: • All contact regions defined between the same pairs of parts/bodies must have the same type. Mixing different types (e.g., frictionless and rough) may lead to incorrect results. • All contact regions defined between the same pairs of parts/bodies must follow the same order. A body defined as a target body in one contact region must not be defined as contact body in another contact region between the same pairs of parts/bodies.

Best Practices for Specifying Contact Conditions This section describes some of the practices you should try to keep in mind while defining the properties of the contact conditions for your model. • Mesh Requisites • Selecting Contact Formulation • Overlapping Contact Conditions and Boundary Conditions • Contact Behavior • Initial Contact Tool • Diagnostic Tools, NR Residuals, and Contact Result Trackers • Contact Tool Results

Mesh Requirements Defining a proper mesh is critical to contact conditions. A well-defined mesh ensures accurate stress measurements at a contact region. Furthermore, a quality mesh is essential for nonlinear contact conditions in order to obtain an accurate solution. This is especially true for curved surfaces. Use local Mesh Controls, such as Proximity Controls and Contact Sizing controls to better ensure mesh quality. Review the Apply Mesh Controls and Preview Mesh section of the Help for more information on this topic.

Selecting Contact Formulation Mechanical provides the following options for the Formulation property:

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Contact • Augmented Lagrange • Pure Penalty • MPC (Multi-Point Constraint) • Normal Lagrange Formulation methods work in combination with the specified contact Types (Bonded, No Separation, Frictionless, Rough, Frictional, and Forced Frictional Sliding). The Augmented Lagrange method is the default Formulation property for all contact types. However, you can use the Bonded and No Separation contact types with the Multi-Point Constraint (MPC) Formulation method. The examples listed below outline cases when this option is useful. Please see the Selecting a Contact Algorithm (KEYOPT(2)) section of the Mechanical APDL Contact Technology Guide for additional technical information about choosing contact formulations. • Workbench Mechanical considers the Bonded and No Separation contact types to be “linear contact.” Generally, this means that if no other nonlinearities exist (plasticity, large deformation, or frictionless contact) a nonlinear solution is not required in order to obtain an accurate solution. If a Formulation is not MPC-based, Mechanical constructs the input file to enforce a single iteration solution by issuing the NEQIT,1,FORCE command (in rare conditions this can result in an inaccurate solution, such as when a contact region is touching a constraint or a rigid body that has both a contact region and a remote displacement). In order to avoid this, you can use the MPC Formulation on the contact pairs to enable a truly linear solution or you can modify the boundary conditions to avoid contact overlap. • In a nonlinear analysis when convergence difficulties occur from Bonded/No-Separation contact situations, switching to MPC can be an attractive alternative compared to modifying the contact stiffness. A common example is where there is significant initial penetration. This is fine for a linear solution run but the presence of non-linear features can cause convergence issues. You can view NR residuals to help determine the proximity of convergence troubles. • During a Modal analysis, MPC can be employed to avoid spurious non-zero modes when gaps exist between curved surfaces. It is an inherent limitation of penalty based contact that is avoided by using an MPC based formulation. • Shell/Solid contact: When bonding shell edges to a solid, you need to make sure that the connection will properly constrain the two sides. The default (penalty-based) Formulation is not able to constrain rotational degrees of freedom that would create the possibility of a rigid body mode in cases such as a straight shell edge connected to a solid face. You can overcome this by using an MPC formulation that does provide options to constrain/couple the translation and rotation degrees of freedom.

Overlapping Contact Conditions and Boundary Conditions To avoid contact conditions that overlap constraints, use the Bonded or No Separation contact types because you will see an overall correct solution, however, the reported reactions will be inaccurate. This same phenomenon occurs in a less obvious way when you attempt to apply a Remote Displacement to a rigid body that also has bonded contact using a penalty based formulation. The example illustrated below shows a remote constraint applied to a rigid body that is also has No Separation contact using a penalty formulation. In this example, the solution is correct, however, inacRelease 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Setting Connections curate reactions are obtained on the Remote Displacements because it is connected to the contact region via the MPC equations created. Using a remote displacement causes the solver to reorder the CE’s such that constrained node shares a CE with the bonded contact. This results in inaccurate reactions.

Using a General Joint instead of a remote displacement avoids the issue.

Regardless of the MPC formulation selection, MPC-based contact is used for Remote Boundary conditions. It is good practice to avoid having two or more MPC-based boundary conditions overlap. The solver does however attempt to negotiate and resolve the overconstraint conditions. The application issues a warning in this situation. Intelligent use of Contact Trimming as well as the Pinball setting on remote boundary conditions can also be effective tools to mitigate this behavior. In addition, MPC as well as other FE connections can be viewed via the Solution Information feature to help you graphically view the distribution of MPC equations in a model. These equations are generated from the MAPDL contact elements. See the Using Finite Element Access to Resolve Overconstraint tutorial for an example of an overconstraint situation along with steps to identify and correct it.

Contact Behavior Properly choosing your source and target topology is also important. See the specific guidelines outlined in the MAPDL contact documentation. The default behavior is auto-asymmetric wherein the MAPDL

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Contact solver determines the optimal source/target. Using a pure asymmetric behavior is suggested only for users willing to closely review each contact pair and able to determine the proper configuration.

Tip Using the Initial Contact tool can help you determine which side the MAPDL solver chooses to keep in the analysis.

Initial Contact Tool The Initial Contact Tool can be invaluable in determining that the contact is properly defined. It is also useful to determine the proper side for the source/target. Further the Initial Contact Tool can be useful to: • Make sure that the option Bonded or No Separation are selected for the Type property when contact conditions are touching and that all Rough/Frictional/Frictionless contact pairs that should be closed are, in fact, closed. • For nonlinear contact, check the amount of penetration (if any). • Even if nonlinear contact regions are in contact, make sure that more than one or two contact points are in contact, because if only one contact point is in contact, the condition may be unstable.

Diagnostic Tools, NR Residuals, and Contact Result Trackers You can use NR residuals and result trackers to help obtain a fully converged analysis. For example: • Requesting three to four Newton-Raphson residuals under the Solution Information object before starting the solution allows you to graphically view the NR residuals so as to get a qualitative measure/indication for where convergence difficulties exist in the model. • Using Contact Result Trackers provides information during the solution, such as contact penetration, the number of elements in contact, contact stiffness values, as well as many other quantities. You can use these outputs to monitor the robustness of the solution and observe the trends occurring during a nonlinear incremental solution. • If there are a few nonlinear contact regions present and you are expecting the possibility of losing contact, you can also use the Results Tracker to add the number of contacting points for those contact regions. • If no convergence is achieved, check the NR residuals. If high residuals are present at contact regions, consider using aggressive automatic contact stiffness update or reducing contact stiffness by an order of magnitude. • While solving, if bisections occur (i.e., trouble converging), check Results Tracker to see if the number of contact points is decreasing (i.e., possible loss of contact).

Contact Tool Results Following the solution process, it is strongly recommend that you insert a Contact Tool to check penetration. Penetration units are the same as that of displacement - compared with displacements in local area.

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Setting Connections For example, if local displacements are 2mm but penetration is 0.02mm, would a change in displacements by +/- 0.02mm influence overall results (including local stresses)? By comparing penetration to the results in local area (not maximum deformations of entire model), you can determine if penetration values are acceptable or not.

Caution Do not assume that penetration values are always negligible because your solution converged. You need to verify this after the solution. If you believe that penetration is excessive, modify the Penetration Tolerance (Augmented Lagrange), Normal Stiffness (Penalty or Augmented Lagrange), or use the Pure Lagrange formulation to reduce the penetration.

Joints The following topics are covered in this section: Joint Characteristics Joint Types Joint Properties Joint Stiffness Manual Joint Creation Example: Assembling Joints Example: Configuring Joints Automatic Joint Creation Joint Stops and Locks Ease of Use Features Detecting Overconstrained Conditions

Joint Characteristics A joint typically serves as a junction where bodies are joined together. Joint types are characterized by their rotational and translational degrees of freedom as being fixed or free. If you specify a Joint as a Remote Attachment it is classified as a remote boundary condition. Refer to the Remote Boundary Conditions (p. 833) section for a listing of all remote boundary conditions and their characteristics. Joints are supported in the following structural analyses: • Harmonic Response • Modal • Random Vibration • Response Spectrum • Rigid Dynamics • Static Structural

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Joints • Transient Structural

Note A Joint cannot be applied to a vertex scoped to an end release.

Nature of Joint Degrees of Freedom • For all joints that have both translational degrees of freedom and rotational degrees of freedom, the kinematics of the joint is as follows: 1. Translation: The moving coordinate system translates in the reference coordinate system. If your joint is a slot for example, the translation along X is expressed in the reference coordinate system. 2. Once the translation has been applied, the center of the rotation is the location of the moving coordinate system. • For the ANSYS Mechanical APDL solver, the relative angular positions for the spherical, general, and bushing joints are characterized by the Cardan (or Bryant) angles. This requires that the rotations about the local Y axis be restricted between –π/2 to +π/2. Thus, the local Y axis should not be used to simulate the axis of rotation if the expected rotation is large.

Joint Abstraction Joints are considered as point-to-point in the solution but the user interface shows the actual geometry. Due to this abstraction to a point-to-point joint, geometry interference and overlap between the two parts linked by the joint can be seen during an animation.

Joint Initial Conditions The nature of the degrees of freedom differs based on the selected solver. For the ANSYS Rigid Dynamics solver, the degrees of freedom are the relative motion between the parts. For the ANSYS Mechanical solver, the degrees of freedom are the location and orientation of the center of mass of the bodies. Unless specified otherwise by using joint conditions, both solvers will start with initial velocities equal to zero, but that means two different things, as explained below. • For the ANSYS Mechanical APDL solver, not specifying anything means that the bodies will be at rest. • For the ANSYS Rigid Dynamics solver, not specifying anything means that the relative velocities will be at rest. Taking the example of an in-plane double pendulum, and prescribing a constant velocity for the first grounded link will be interpreted as follows: • The second link has the same rotational velocity as the first one for the ANSYS Rigid Dynamics solver, as the relative velocity is initially equal to zero. • The second link will start at rest for the ANSYS Mechanical APDL solver.

Joint DOF Zero Value Conventions Joints can be defined using one or two coordinate systems: the Reference Coordinate System and the Mobile Coordinate System. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Setting Connections The use of two coordinate systems provides benefits. An example is when a CAD model is not imported in an assembled configuration. In addition, it is important to define two coordinate systems so that you can employ the Configure and Set (see Manual Joint Creation (p. 564)) features as well as having the ability to update a model following a CAD update. For the ANSYS Rigid Dynamics solver, the zero value of the degrees of freedom corresponds to the matching reference coordinate system and moving coordinate system. If a joint definition includes only the location of the Mobile Coordinate System (see Modifying Joint Coordinate Systems (p. 554)), then the DOF of this joint are initially equal to zero for the geometrical configuration where the joints have been built. If the Reference Coordinate System is defined using the Override option, then the initial value of the degrees of freedom can be a nonzero value. Consider the example illustrated below. If a Translational joint is defined between the two parts using two coordinate systems, then the distance along the X axis between the two origins is the joint initial DOF value. For this example, assume it is 65 mm.

On the other hand, if the joint is defined using a single coordinate, as shown below, then the same geometrical configuration has a joint degree of freedom that is equal to zero.

For the ANSYS Mechanical APDL solver, having one or two coordinate systems has no impact. The initial configuration corresponds to the zero value of the degrees of freedom. Joint Condition Considerations When applying a Joint Condition, differences between the two solvers can arise. For example, consider the right part illustrated above moving 100 mm towards the other part over a 1 second period. (The distance along the X axis is 65 mm.) Solver ANSYS Rigid Dynamics – Two Coordinate Systems

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Displacement Joint Condition Time

Displacement

0

65

1

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Joints ANSYS Rigid Dynamics – One Coordinate System

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ANSYS Mechanical APDL – Two Coordinate Systems

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ANSYS Mechanical APDL – One Coordinate System

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You can unify the joint condition input by using a Velocity Joint Condition. Solver

Velocity Joint Condition Time

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ANSYS Rigid Dynamics – Two Coordinate Systems

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ANSYS Rigid Dynamics – One Coordinate System

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Joint Types You can create the following types of joints in the Mechanical application: • Fixed Joint (p. 546) • Revolute Joint (p. 546) • Cylindrical Joint (p. 546) • Translational Joint (p. 547) • Slot Joint (p. 547) • Universal Joint (p. 548) • Spherical Joint (p. 548) • Planar Joint (p. 549) • Bushing Joint (p. 549) • General Joint (p. 551) • Point on Curve Joint (p. 552) The following sections include animated visual joint representations. Please view online if you are reading the PDF version of the help.

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Setting Connections

Fixed Joint • Constrained degrees of freedom: All

Revolute Joint • Constrained degrees of freedom: UX, UY, UZ, ROTX, ROTY

• Example:

Cylindrical Joint • Constrained degrees of freedom: UX, UY, ROTX, ROTY

• Example:

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Joints

Translational Joint • Constrained degrees of freedom: UY, UZ, ROTX, ROTY, ROTZ

• Example:

Slot Joint • Constrained degrees of freedom: UY, UZ

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Setting Connections

Universal Joint • Constrained degrees of freedom: UX, UY, UZ, ROTY

• Example:

Spherical Joint • Constrained degrees of freedom: UX, UY, UZ

• Example:

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Joints

Planar Joint • Constrained degrees of freedom: UZ, ROTX, ROTY

• Example:

Bushing Joint • Constrained degrees of freedom: None

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Setting Connections • Example:

• A Bushing has six degrees of freedom, three translations and three rotations, all of which can potentially be characterized by their rotational and translational degrees of freedom as being free or constrained by stiffness. For a Bushing, the rotational degrees of freedom are defined as follows: – The first is a rotation around the reference coordinate system X Axis. – The second is a rotation around the Y Axis after the first rotation is applied. – The third is a rotation around the Z Axis after the first and second rotations are applied. The three translations and the three rotations form a set of six degrees of freedom. In addition, the bushing behaves, by design, as an imperfect joint, that is, some forces developed in the joint oppose the motion. The three translational degrees of freedom expressed in the reference coordinate system and the three rotations are expressed as: Ux, Uy, Uz, and Ψ, Θ, φ. The relative velocities in the reference coordinate system are expressed as: Vx, Vy, and Vz. The three components of the relative rotational velocity are expressed as: Ωx, Ωy, and Ωz. Please note that these values are not the time derivatives of [Ψ, Θ, φ]. They are a linear combination. The forces developed in the Bushing are expressed as:

Where:

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Joints [F] is force and [T] is Torque, and [K] and [C] are 6x6 matrices (defined using Stiffness Coefficients and Dampening Coefficients options). Off diagonal terms in the matrix are coupling terms between the DOFs. You can use these joints to introduce flexibility to an over-constrained mechanism. Please note that very high stiffness terms introduce high frequencies into the system and may penalize the solution time when using the ANSYS Rigid Dynamics solver. If you want to suppress motion in one direction entirely , it is more efficient to use Joint DOF Zero Value Conventions instead of a very high stiffness.

Scoping You can scope a bushing to single or multiple faces, single or multiple edges, or to a single vertex. The scoping can either be from body-to-body or body-to-ground. For body-to-body scoping, there is a reference and mobile side. For body-to-ground scoping, the reference side is assumed to be grounded (fixed), scoping is only available on the mobile side. In addition to setting the scoping (where the bushing attaches to the body), you can set the bushing location on both the mobile and reference side. The bushing reference and mobile location cannot be the same.

Applying a Bushing To add a bushing: 1.

After importing the model, highlight the Connections object in the tree.

2.

Choose either Body-Ground>Bushing or Body-Body>Bushing from the toolbar, as applicable.

3.

Highlight the new Bushing object and enter information in the Details view.

Note that matrix data for the Stiffness Coefficients and Dampening Coefficients is entered in the Worksheet. Entries are based on a Full Symmetric matrix. • A nonlinear force-deflection curve can be used to simulate multi-rate bushing with nonlinear stiffness. A linear piecewise curve is used for this purpose. To define a nonlinear stiffness-deflection curve: 1.

In the Worksheet, select the cell in which you want to define a non-linear stiffness-deflection curve.

2.

Right-click on the cell and then select Constant or Tabular.

3.

Enter a constant stiffness value or enter displacement and stiffness values (minimum of two rows of data) in the Tabular Data window. Tabular entries are plotted in the Graph window and show stiffness vs. displacement.

Note If tabular entries exist in the stiffness matrix, the MAPDL Solver does not account for constant terms and non-diagonal (coupled) terms.

General Joint • Constrained degrees of freedom: Fix All, Free X, Free Y, Free Z, and Free All.

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Setting Connections A general joint has six degrees of freedom, three translations and three rotations, all of which can potentially be characterized by their rotational and translational degrees of freedom as being free or constrained by stiffness. All the degrees of freedom are set to fixed by default. You can free the X translation, free the Y translation, free the Z translation and free all rotations. All the translational degrees of freedom can be controlled individually to be fixed or free. But there are no individual controls for rotational degrees of freedom. You can either set all rotations fixed, or just one of them (X, Y or Z) free or all free. Also, similar to a bushing, you can enter matrix data for the Stiffness Coefficients and Damping Coefficients in the Worksheet. Coupled terms (off diagonal terms in the matrix) are only allowed when all DOFs are free.

Point on Curve Joint • Constrained degrees of freedom: UY, UZ, ROTX, ROTY, ROTZ • Example:

• A point on curve joint has only one degree of freedom, which is the coordinate on the curve. UY and UZ are always equal to zero. ROTX, ROTY, and ROTZ are driven so that the mobile coordinate system of the joint always follows the reference curve. For a point on curve joint, the X axis is always tangent to the reference curve, and the Z axis is always normal to the orientation surface of the joint, pointing outward.

Scoping You can scope a point on curve joint to a single curve or multiple reference curves. You can have one or more orientation surfaces. The mobile coordinate system has to be scoped to a vertex, and the joint coordinate system has to be positioned and oriented such that: – The origin is on the curve.

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Joints – The X axis is tangent to the curve. – The Z axis is the outer normal to the surface. Note that the assembly phase may result in minor adjustments to ensure that the mobile coordinate system is properly positioned.

Joint Properties This section describes the Details view properties associated with a Joint object. Category

Property Name and Description

Definition

Connection Type Connection Type: The Connection Type property specifies the joint as either a Body-Body scoping (multiple faces) or a Body-Ground scoping (multiple faces). When defined as Body-Body, you need to define Reference category and Mobile category properties. When you specify the Connection Type as body-to-ground, the application assumes that the reference element of the joint is grounded (fixed). Type The Type property provides a drop-down list from which you can select a joints type. Refer to the Joint Types (p. 545) section of the Help for descriptions of each type. In addition to provided joint types, you can create a General joint that allows you to specify each degree of freedom as being either Fixed or Free. Torsional Stiffness The Torsional Stiffness property defines the measure of the resistance of a shaft to a twisting or torsional force. You can add torsional stiffness only for cylindrical and revolute joints. Torsional Damping The Torsional Damping property defines the measure of resistance to the angular vibration to a shaft or body along its axis of rotation. You can add torsional damping only for cylindrical and revolute joints. Suppressed Includes or excludes the joint object in the analysis.

Reference

Scoping Method This property allows you to choose to scope using a Geometry Selection (default), Named Selection, or a user-defined Remote Point.

Note If you scope a joint to a user-defined Remote Point, it is required that the remote point be located at the origin (0.0, 0.0, 0.0) of the Reference Coordinate System of the remote point. Applied By This property specifies the joint as a Remote Attachment (default) or a Direct Attachment. The Remote Attachment option uses either a user-defined or a system-generated Remote Point as a scoping mechanism. Remote Attachment Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Setting Connections Category

Property Name and Description is the required Applied By property setting if the geometry scoping is to a single face or multiple faces, a single edge or multiple edges, or multiple vertices. The Direct Attachment option allows you to scope directly to a single vertex (Geometry) or a node (using an individually selected node or a node-based Named Selection) for flexible bodies (only) on your model. Direct Attachment is not allowed if scoped to solid bodies, as they do not have rotational degrees of freedom. Scope (or Reference Component or Remote Point) Based on the selected Scoping Method, this property displays as either "Scope", "Reference Component", or "Remote Points". When Geometry Selection is selected as the Scoping Method, this property displays with the label "Scope" and allows you to define the geometry to which the joint is applied. Once a geometry is selected, click in the Scope field and then click Apply. When Named Selection is selected as the Scoping Method, this property provides a drop-down list of available user-defined Named Selections. When Remote Point is selected as the Scoping Method, this property displays with the label "Remote Points". This property provides a drop-down list of available user-defined Remote Points. This property is not available when the Applied By property is specified as Direct Attachment. Body This read-only property displays the corresponding part/geometry name. Coordinate System The scoping of a joint must be accompanied by the definition of a joint coordinate system. This coordinate system defines the location of the joint. It is imperative that the joint coordinate system be fully associative with the geometry, otherwise, the coordinate system could move in unexpected ways when the Configure tool is used to define the initial position of the joint (see the Applying Joints section). A warning message is issued if you attempt to use the Configure tool with a joint whose coordinate system is not fully associative. Under the Reference category, the Coordinate System property provides a default Reference Coordinate System. This coordinate system accompanies a joint when the joint is added to the tree. This applies for joints whose Connection Type is either Body-Ground or Body-Body. When a joint is added, an associated coordinate system is automatically generated at a location based on the selected geometry (face, edge, or vertex). You can modify the Reference Coordinate System’s orientation axis by modifying the details of the Reference Coordinate System object contained in the joint object. Scoping a joint directly to a vertex or a node using the Direct Attachment option fixes the coordinate system to that location. Note that the Reference Coordinate System property displays automatically and is read-only. You can modify the Reference Coordinate System’s orientation axis using the Details properties in the Reference Coordinate System tree object contained under the joint object.

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Joints Category

Property Name and Description Additional information about Modifying Joint Coordinate Systems is also available, including the following topics: • Modify Coordinate System Geometry Scoping • Change Coordinate System Orientation Behavior Use the Behavior property to specify the scoped geometry as either Rigid or Deformable. Refer to the Geometry Behaviors and Support Specifications (p. 464) section for more information. Pinball Region Use the Pinball Region property to define where the joint attaches to face(s) if the default location is not desirable. By default, the entire face is tied to the joint element. This may not be desirable, warranting the input of a Pinball Region setting, for the following reasons: • If the scoping is to a topology with a large number of nodes, this can lead to an inefficient solution in terms of memory and speed. • Overlap between the joint scoped faces and other displacement type boundary conditions can lead to over constraint and thus solver failures.

Note • The Pinball Region and Behavior settings are applicable to underlying bodies that are flexible. • If a Joint’s Reference and Mobile category are scoped to separate Remote Points, the Behavior and Pinball Region properties for each category become read-only and are set to the respective remote points. Mobile

Scoping Method This property allows you to choose to scope using a Geometry Selection (default), Named Selection, or a user-defined Remote Point.

Note If you scope a joint to a user-defined Remote Point, it is required that the remote point be located at the origin (0.0, 0.0, 0.0) of the Reference Coordinate System of the remote point. Applied By This property specifies the joint as a Remote Attachment (default) or a Direct Attachment. The Remote Attachment option uses either a user-defined or a system-generated Remote Point as a scoping mechanism. Remote Attachment is the required Applied By property setting if the geometry scoping is to a single face or multiple faces, a single edge or multiple edges, or a single vertex or multiple

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Setting Connections Category

Property Name and Description vertices. The Direct Attachment option allows you to scope directly to a single vertex (Geometry) or a node (using an individually selected node or a node-based Named Selection) to flexible bodies (only) on your model. Direct Attachment is not allowed if scoped to solid bodies, as they do not have rotational degrees of freedom. Scope (or Mobile Component or Remote Point) Based on the selected Scoping Method, this property displays as either "Scope", "Mobile Component", or "Remote Points". When Geometry Selection is selected as the Scoping Method, this property displays with the label "Scope" and allows you to define the geometry to which the joint is applied. Once a geometry is selected, click in the Scope field and then click Apply. When Named Selection is selected as the Scoping Method, provides a dropdown list of available user-defined Named Selections. When Remote Point is selected as the Scoping Method, this property displays with the label "Remote Points". This property provides a drop-down list of available user-defined Remote Points. This property is not available when the Applied By property is specified as Direct Attachment. Body This property is available under both the Reference and Mobile categories. This read-only property displays the corresponding part/geometry name. Coordinate System The Mobile category provides the support for the relative motion between the parts of a joint. A Mobile Coordinate System is automatically defined but is only displayed in the tree when the Initial Position property is set to Override. Scoping a joint directly to a vertex or a node using the Direct Attachment option fixes the coordinate system to that location. When scoping directly to a node or vertex using the Direct Attachment option, the default setting for the Initial Position property is Override even though the Initial Position property doesn't display in the Details. Rather, the Coordinate System automatically displays and is read-only. You can modify the Mobile Coordinate System’s orientation axis using the Details properties in the Mobile Coordinate System tree object contained in the joint object. Additional information about Modifying Joint Coordinate Systems is also available, including the following topics: • Modify Coordinate System Geometry Scoping • Change Coordinate System Orientation Initial Position This property applies to remote attachments only (direct attachments fix the coordinate system). It provides a drop-down list with the options Unchanged and Override. The Unchanged option indicates the use of the same coordinate system for the Reference category and the Mobile category and the Override option

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Property Name and Description causes a Coordinate System property to display in the Mobile category with the default setting Mobile Coordinate System.

Caution If you are scoping a joint to a Remote Point, you cannot scope the Initial Position setting of a Joint's Mobile category as Unchanged. This is also true when the Direct Attachment option is used because the Initial Position property is not available (Override is active). Behavior For remote attachments, use the Behavior property to specify the scoped geometry as either Rigid or Deformable. Refer to the Geometry Behaviors and Support Specifications (p. 464) section for more information. Pinball Region For remote attachments, use the Pinball Region property to define where the joint attaches to face(s) if the default location is not desirable. By default, the entire face is tied to the joint element. This may not be desirable, warranting the input of a Pinball Region setting, for the following reasons: • If the scoping is to a topology with a large number of nodes, this can lead to an inefficient solution in terms of memory and speed. • Overlap between the joint scoped faces and other displacement type boundary conditions can lead to over constraint and thus solver failures.

Note • The Pinball Region and Behavior properties are not visible when the Applied By method is Direct Attachment. • The Pinball Region and Behavior settings are applicable to underlying bodies that are flexible. • If a Joint’s Reference and Mobile category are scoped to separate Remote Points, the Behavior and Pinball Region properties for each category become read-only and are set to the respective remote points. Stops

See the Joint Stops and Locks (p. 590) section.

Modifying Joint Coordinate Systems For either Reference or Mobile joint coordinate systems, both the location and the orientation of the coordinate system can be changed as shown below.

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Setting Connections To move a joint coordinate system to a particular face: 1.

Highlight the Coordinate System field in the Details view of the Joint object. The origin of the coordinate system will include a yellow sphere indicating that the movement “mode” is active.

2.

Select the face that is to be the destination of the coordinate system. The coordinate system in movement mode relocates to the centroid of the selected face.

3.

Click the Apply button. The image of the coordinate system changes from movement mode to a permanent presence at the new location.

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To change the orientation of a joint coordinate system: 1.

Highlight the Coordinate System field in the Details view of the Joint object. The origin of the coordinate system will include a yellow sphere indicating that the movement “mode” is active.

2.

Click on any of the axis arrows you wish to change. Additional “handles” are displayed for each axis.

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3.

Click on the handle or axis representing the new direction to which you want to reorient the initially selected axis.

The axis performs a flip transformation.

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4.

Click the Apply button. The image of the coordinate system changes from movement mode to a permanent presence at the new orientation.

You can change or delete the status of the flip transformation by highlighting the Reference Coordinate System object or a Mobile Coordinate System object and making the change or deletion under the Transformations category in the Details view of the child joint coordinate system.

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When selecting either a Reference Coordinate System object or a Mobile Coordinate System object, various settings are displayed in the Details view. These are the same settings that apply to all coordinate systems, not just those associated with joints. See the following section on coordinate systems: Initial Creation and Definition (p. 483) for an explanation of these settings.

Joint Stiffness For Bushing and General Joints, Mechanical allows you to solve analyses with linear and nonlinear joint stiffness using the features of the Worksheet. For these joint types, the Worksheet provides the entry options for Constant and Tabular data. Linear or nonlinear stiffness and damping behavior is associated with the free or unrestrained components of relative motion of the joint elements. That is, the DOFs are free. For a General Joint, you must specify the DOFs as Free in order to make entries in the Worksheet matrix. Joint Stiffness calculations use the joint element MPC184. Please see its help section in the Mechanical APDL Element Reference for additional technical information as well as the MPC184 Joint Help section in the Mechanical APDL Material Reference.

Linear Joint Stiffness In the case of linear stiffness or linear damping, the values are specified as coefficients of a 6 x 6 elasticity table matrix. Joint Stiffness calculations use the joint element MPC184 and therefore only the appropriate coefficients of the stiffness or damping matrix are used in the joint element calculations.

Nonlinear Joint Stiffness For nonlinear joint stiffness, relative displacement (rotation) versus force (moment) values are calculated. For nonlinear damping behavior, velocity versus force behavior is specified. You specify nonlinear damping behavior by supplying velocity versus damping force (or moment). The following illustration represents a nonlinear stiffness or damping curve. Note that the MAPDL Solver and the Rigid Dynamics Solver assume that there is no added stiffness past the extents.

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Please see the Material Behavior of Joint Elements topic of the Connecting Multibody Components with Joint Elements section in the Mechanical APDL Multibody Analysis Guide for additional details about how this feature related to the Mechanical APDL Application.

Worksheet Using the Worksheet, you can define Stiffness Coefficients in Constant or Tabular format. Nonlinear Joint Stiffness is supported by Tabular data entries only and the entries must be made diagonally. In addition, Damping Coefficients entries only support constant values.

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Note • The MAPDL Solver does not support a mixture of Constant and Tabular data entries in the Stiffness Coefficients matrix. That is, you cannot mix linear and nonlinear stiffness. • The ANSYS Rigid Dynamics Solver does support the combination of Constant and Tabular data entries. • The Report Preview feature does not display table entries from the nonlinear joint stiffness matrix.

Manual Joint Creation This section examines the steps to manually create joints. Refer to the Automatic Joint Creation (p. 589) section of the Help for a discussion about how to create joints automatically. To add a joint manually: 1.

Joints are a child object of the Connections object. The Connections object is typically generated automatically. As needed, highlight the Model object in the tree and choose the Connections button from the Model Context Toolbar once you have imported your model.

2.

Highlight the Connections object and open either Body-Ground menu or the Body-Body menu from the Connections Context Toolbar and then select your desired Joint Type. The new joint object becomes the active object in the tree.

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Joints 3.

Once inserted and active, there are a number of joint properties that require definition. For a detailed description of each of these properties, refer to the Joint Properties Help section.

Tip The Body Views button in the toolbar displays the Reference and Mobile bodies in separate windows with appropriate transparencies applied. You have full body manipulation capabilities in each of these windows.

Note You can pre-select a vertex or node (Body-Ground) or two vertices or nodes (BodyBody) and then insert a Joint to automatically create a directly attached joint.

4.

Once you have defined the desired joint properties, you may wish to use the Configure tool. The Configure tool is activated by selecting the Configure button on the Joint Configure Context Toolbar. This feature positions the Mobile body according to the joint definitions. You can then manipulate the joint interactively (for example, rotate the joint) directly on the model. The notes section shown below provides additional information about the benefits and use of the Configure feature (as well as the Assemble feature). In addition, refer to the Example: Configuring Joints Help section for an example of the use of the Configure tool.

Note • The Configure tool is not supported for Joints scoped as a Direct Attachment. • The Set button in the toolbar locks the changed assembly for use in the subsequent analysis. • The triad position and orientation may not display correctly until you click on the Set button. • The Revert button in the toolbar restores the assembly to its original configuration from DesignModeler or the CAD system.

5.

It is suggested that you consider the following: • Renaming the joint objects based on the type of joint and the names of the joined geometry. • Display the Joint DOF Checker and modify joint definitions if necessary. • Create a redundancy analysis to interactively check the influence of individual joint degrees of freedom on the redundant constraints.

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Configure and Assemble Tools Notes The Configure and Assemble tools are a good way to exercise the model and joints before starting to perform a transient analysis. They are also a way to detect locking configurations. The Assemble tool performs the assembly of the model, finding the closest part configuration that satisfies all the joints. The Configure tool performs the assembly of the model, with a prescribed value of the angle or translational degree of freedom that you are configuring. For the Assemble tool, all the joints degrees of freedom values are considered to be free. For the Configure joint, the selected DOF is considered as prescribed. In both cases, the solver will apply all constraint equations, solve the nonlinear set of equations, and finally verify that all of them are satisfied, including those having been considered as being redundant. The violation of these constraints is compared to the model size. The model size is not the actual size of the part – as the solver does not use the actual geometry, but rather a wireframe representation of the bodies. Each body holds some coordinate systems – center of mass, and joint coordinate systems. For very simple models, where the joints are defined at the center of mass, the size of the parts is zero. The violation of the constraint equations is then compared to very small reference size, and the convergence becomes very difficult to reach, leading the Configure tool or the Assemble tool to fail.

Example: Assembling Joints This section illustrates the details of assembling geometry using an example of a three-part a pendulum joint model. The Assemble feature allows you to bring in CAD geometry that may initially be in a state of disassembly. After importing the CAD geometry, you can actively assemble the different parts and Set them in the assembled configuration for the start of the analysis. The geometry shown for the example in Figure 20: Initial Geometry (p. 567) was imported into a Rigid Dynamics analysis System.

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Joints Figure 20: Initial Geometry

This geometry consists of three bodies. In Figure 20: Initial Geometry (p. 567) they are (from left to right) the Basis, the Arm, and the PendulumAxis. These three bodies have been imported completely disjointed/separate from each other. The first step to orient and assemble the bodies is to add a Body-Ground Fixed joint to the body named Basis. To do this: 1. Select Connections from the Outline. 2. From the context sensitive menu, choose Body-Ground > Fixed.

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Setting Connections 3. Click on a flat external face on the Basis body as seen in Figure 21: Selecting a Face for a Body-Ground Fixed Connection (p. 568). 4. In the Details view under Mobile, click in the Scope field and select Apply. Figure 21: Selecting a Face for a Body-Ground Fixed Connection

Next, you need to join the PendulumAxis to the Basis. Since they are initially disjoint, you need to set two coordinate systems, one for the Basis and the other for the PendulumAxis. Additionally, to fully define the relative position and orientations of the two bodies, you must define a fixed joint between them. To do this: 1. From the context sensitive menu, click on Body-Body > Fixed. 2. Highlight the face on the Basis as shown below.

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Joints

3. In the Details view, click on the Scope field under Reference and select Apply. 4. Select the cylindrical face on the PendulumAxis. 5. In the Details view, select the Scope field under Mobile and select Apply. Figure 22: Creating a Mobile Coordinate System

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Setting Connections 6. Also, change the Initial Position value under Mobile from Unchanged to Override. Now, the joint has two coordinate systems associated with it: A Reference and a Mobile coordinate system. Next, you must associate the Reference and the Mobile Coordinate Systems to the respective bodies with the appropriate orientations. To associate the Reference Coordinate System to the respective bodies: 1. In the Outline, highlight Reference Coordinate System. 2. In the Details view, click on the box next to Geometry under Origin. 3. Select the two internal rectangular faces on the Basis as shown in Figure 23: Creating the Reference Coordinate System (p. 570) and in the Details view, select Apply. This will center The Reference Coordinate System at the center of the hole on the Basis. Figure 23: Creating the Reference Coordinate System

To associate the Mobile Coordinate System to the respective bodies: 1. Highlight the Mobile Coordinate System (this coordinate system is associated with the Basis). 2. In the Details view, click in the Geometry field under Origin. 3. Select the cylindrical surface on the PendulumArm. 570

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Joints 4. In the Details view, click Apply. Figure 24: Creating the Mobile Coordinate System

Next, you will need to orient the PendulumAxis coordinate system so that it is oriented correctly in the assembly: 1. In the Mobile Coordinate System associated with the PendulumAxis, click in the box next to Geometry under Principal Axis (set to Z). 2. Select one of the vertical edges on the PendulumAxis such that the Z axis is parallel to it as shown in Figure 25: Orienting the Pendulum Axis (p. 572). In the Details view, click Apply.

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Setting Connections Figure 25: Orienting the Pendulum Axis

3. With Mobile Coordinate System highlighted in the Outline, select the x-offset button in the context sensitive menu. 4. In the Details view, enter an Offset X value of 2.5mm to align the faces of the PendulumAxis with the Basis.

Note The transformations available allow you to manipulate the coordinate systems by entering offsets or rotations in each of the 3 axis.

The two coordinate systems that were just defined should look similar to the figure below. Figure 26: Oriented Coordinate Systems

Next, you will need to define the coordinate systems to join the Arm to the PendulumAxis during assembly.

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Joints 1. From the context sensitive menu, select Body-Body > Fixed. 2. To define the Reference Scope, choose one of the faces of the Arm that will be connected to the PendulumAxis then select Apply. Figure 27: Selecting an Arm Face for Connection

3. Now, configure the Mobile Scope by selecting the flat end face of the PendulumAxis as shown in Figure 28: Scoping the Mobile Coordinate Systems (p. 574), then select Apply.

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Setting Connections Figure 28: Scoping the Mobile Coordinate Systems

4. Set the Initial Position under Mobile from Unchanged to Override. 5. Finally, set the Origin of the Reference Coordinate System to the center of the hole in the Arm using the same procedure described above for the Basis. Next, you will need to offset the Coordinate System associated with the Arm so that the faces on the Arm are aligned with the end face of the PendulumAxis. 1. With Reference Coordinate System highlighted, choose the x-offset button in the context sensitive menu. 2. Enter an Offset X value of -5mm.

Note The transformations available allow you to manipulate the coordinate systems by entering offsets or rotations in each of the 3 axis.

3. Next, Highlight the Mobile Coordinate System. This coordinate system is associated with the Arm. Click the box next to Geometry under Origin 4. Select the flat surface on the PendulumArm and click Apply. 574

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Joints

Now you will need to orient the PendulumAxis so that its faces are aligned with the faces on the Arm during the Assemble process. 1. Highlight the Mobile Coordinate System that is assigned to the PendulumAxis. 2. From the Details view, click the in the Geometry field under Principal Axis and select an edge of the PendulumAxis as shown in the figure. Figure 29: Choose an Edge to Orient the PendulumAxis Geometry

3. Under Principal Axis In the Details view, select Apply in the Geometry field to orient the PendulumAxis to this edge. Now that the three bodies have been oriented and aligned, they are ready to be assembled. 1. In the Outline, highlight Connections. 2. From the context sensitive menu, click Assemble.

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Setting Connections The parts should snap together in place and resemble Figure 30: Assembled Geometry (p. 576). If the geometry you're attempting to assemble has not snapped into place as expected, you should retrace your previous steps to make sure that the coordinate systems are properly oriented. If your assembly has been successfully performed, then click Set in the context sensitive menu to place the assembly in its assembled position to start the analysis. Figure 30: Assembled Geometry

End of Example.

Example: Configuring Joints This section presents an example of some common joint configuration steps for a model of a pendulum created from two links, as illustrated below.

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Joints

To achieve the desired result, two revolute joints were created and configured: • The first joint is intended to allow rotation of the top link's upper hole referenced to a stationary point (Body-Ground Revolute Joint). • The second joint is intended to allow rotation of the bottom link's upper hole referenced to the top link's lower hole (Body-Ground Revolute Joint). The following steps illustrate the steps of a common joint configuration: 1. After attaching the model to the Mechanical application, create the first revolute joint. • Select the Connections object in the tree and then open the Body-Ground drop-down menu on from the Connections Context Toolbar and select Revolute. The new joint object becomes the active object in the tree.

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2. Scope the Mobile side of the first revolute joint to the top link's upper hole. • Select the inner surface of the upper hole and then under Mobile category in the Details view, select the Scope field and click the Apply button.

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3. Create the second revolute joint. • Open the Body-Body drop-down menu from the Connections Context Toolbar and select Revolute. The new joint object becomes the active object in the tree.. 4. Scope the Reference side of the second joint to the top link's lower hole. • Select inner surface of hole and the under Reference category in the Details view, select the Scope field and click the Apply button.

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5. Scope the mobile side of the second joint to the bottom link's upper hole. • Select inside surface of hole, then under Mobile category in the Details view, select the Scope field and click the Apply button.

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6. As illustrated here, the two holes intended to form the second joint are not properly aligned to correctly create the revolute joint.

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To align the holes, you need to indicate that the two holes need to match. To achieve this, first create a coordinate system for the mobile side of the second joint, and then align the Mobile and Reference coordinate systems. Create the mobile coordinate system in this step. • Highlight the second joint, Revolute - Solid To Solid, in the tree and select Override from the dropdown menu of the Initial Position property. Note that a new Coordinate System property displays.

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7. Scope the new mobile coordinate system to the back edge of the bottom link's upper hole. • Select the back edge of the bottom link's upper hole, then under Mobile category, select the Coordinate System field, and then click the Apply button.

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8. Scope the existing Reference Coordinate System to the back edge of the top link's lower hole. • Select the back edge of the top link's lower hole, and then under Reference category, select the Coordinate System field and then click the Apply button.

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Joints

The above steps have correctly assigned the coordinate systems so that the holes can be aligned and the revolute joint can operate properly. To verify, highlight the Connections object in the tree and click the Assemble button in the Joint Configure Context toolbar.

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Setting Connections

9. Establish the initial position of each joint. • Highlight the body-to-body joint object in the tree and click the Configure button in the Joint Configure Context Toolbar. The joint is graphically displayed according to your configuration. In addition, a triad appears with straight lines representing translational degrees of freedom and curved lines representing rotational degrees of freedom. Among these, any colored lines represent the free degrees of freedom for the joint type. For the joint that is being configured, the translational displacement degrees of freedom always follow the Geometry units rather than the current Mechanical units.

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By dragging the mouse cursor on a colored line, the joint will move allowing you to set the initial position of the joint through the free translational or rotational degrees of freedom.

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For rotations, holding the Ctrl key while dragging the mouse cursor will advance the rotation in 10 degree increments. You can also type the value of the increment into the ∆ = field on the toolbar. Clicking the Configure button again cancels the joining and positioning of the joint. 10. Create the joints. • After configuring a joint's initial position, click the Set button to create the joint.

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Joints

At this point, you also have the option of returning the configuration to the state it was in before joint creation and upon attaching to the Mechanical application by clicking the Revert toolbar button. End of Example.

Automatic Joint Creation This section discusses the automatic joint creation in the Mechanical application. You can also create joints manually as discussed in Manual Joint Creation (p. 564) section.

Creating Joints Automatically You can direct the Mechanical application to analyze your assembly and automatically create fixed joints and/or revolute joints. To create joints automatically: 1.

Insert a Connection Group object under the Connections folder either from the toolbar button or by choosing Insert from the context menu (right mouse click) for this folder.

2.

From the Details view of the Connection Group object, choose Joint from the Connection Type drop down menu.

3.

Select some bodies in the model based on the Scoping Method. The default is Geometry Selection scoped to All Bodies. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Setting Connections 4.

Configure the types of joints (fixed and/or revolute) you want the Mechanical application to create automatically through the appropriate Yes or No settings in the Details view. These properties will be applied only to scoped geometries for this connection group. You can set defaults for these settings using the Options dialog box under Connections.

Note When both the Fixed Joints and Revolute Joints properties are set to Yes, the revolute joints have priority; the search for revolute joints will be processed first followed by the search for fixed joints.

5.

Choose Create Automatic Connections from the context menu (right mouse click) for the Connection Group. Appropriate joint types are created and appear in the tree as objects under the Joints folder. Each joint also includes a reference coordinate system that is represented as a child object to the joint object.

6.

Display the Joint DOF Checker or the redundancy analysis and modify joint definitions if necessary.

Joint Stops and Locks Stops and Locks are optional constraints that may be applied to restrict the motion of the free relative degree(s) of freedom (DOF) of most types of joints. Any analysis that includes a valid joint type can involve Stops and/or Locks. For the applicable joint types, you can define a minimum and maximum (min, max) range inside of which the degrees of freedom must remain. A Stop is a computationally efficient abstraction of a real contact, which simplifies geometry calculations. For Stops, a shock occurs when a joint reaches the limit of the relative motion. A Lock is the same as a Stop except that when the Lock reaches the specified limit for a degree of freedom the Lock becomes fixed in place.

Warning Use Joint Stops sparingly. The application treats the stop constraint internally as a "must be imposed" or "hard" constraint and no contact logic is used. As a result, during the given iteration of a substep, the stop constraints activate immediately if the application detects a violation of a stop limit. Depending upon the nature of the problem, the stop constraint implementation may cause the solution to trend towards an equilibriated state that may not be readily apparent to you. In addition, do not use stops to simulate zero-displacement boundary conditions. You should also avoid specifying stops on multiple joints. Finally, do not use joint stops as a substitute for contact modeling. Whenever possible, you need to use node-to-node or node-to-surface contact modeling to simulate limit conditions. For joints with free relative DOFs, the Details view displays a group of options labeled Stops. This grouping displays the applicable free DOFs (UX, UY, UZ, ROTX. etc.) for the joint type from which you specify the constraint as a Stop or a Lock (as shown below). By default, no Stop or Lock is specified, as indicated by the default option, None. You can select any combination of options. For stops and locks, the minimum and maximum values you enter are relative to the joint’s coordinate system.

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Radial Gap Stop For joints that have 3 rotational degrees of freedom, a special type of stop called a radial gap stop can be used. A radial gap stop limits the relative rotation of either the X or Y rotation, limiting the Z axis tilt of the joint’s mobile coordinate system with respect to the Z axis of the reference coordinate system. This stop idealizes a revolute joint with a gap between the inner and the outer cylinder that allows the shaft to translate and tilt in the outer cylinder, as shown on the following figure:

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Setting Connections

Where: d is the inner diameter. D is the outer diameter. H is the height of the joint. Important Notes: • The Outer Diameter is considered to be on the reference side of the joint, so you might have to flip reference and mobile on the joint to properly define a radial gap. • The shaft is considered to be infinitely long. • If the joint allows relative translations, the center of the shaft will shift with these translations. The radial gap accounts for this center shift. • The principal axis of the radial gap is Z, meaning that the tilt occurs along the X and Y rotations of the gap. • Radial gap stops do not support tilt angles greater than 1 rad. Stops and Locks are applied to the following Joint Types. Joint Type Revolute

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Stop/Lock ANSYS Rigid Dynamics Stop/Lock ANSYS Mechanical Yes

Yes

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Joints Joint Type

Stop/Lock ANSYS Rigid Dynamics Stop/Lock ANSYS Mechanical

Cylindrical

Yes

Yes

Translational

Yes

Yes

Slot

Translational

Translational

Universal

Yes

Yes

Spherical

Radial Gap

No

Planar

Yes

Yes

General

Translational, Radial Gap

Translational

Bushing

Translational, Radial Gap

Translational

Note • When using the ANSYS Mechanical solver, Stops and Locks are active only when Large Deflection is set to On (under Analysis Settings (p. 1298)). This is because Stops and Locks make sense only in the context of finite deformation/rotation. If Large Deflection is Off, all calculations are carried out in the original configuration and the configuration is never updated, preventing the activation of the Stops and Locks. • It is important to apply sensible Stop and Lock values to ensure that the initial geometry configuration does not violate the applied stop/lock limits. Also, applying conflicting boundary conditions (for example, applying Acceleration on a joint that has a Stop, or applying Velocity on a joint that has a Stop) on the same DOF leads to non-physical results and therefore is not supported.

Solver Implications Stops and Locks are available for both the ANSYS Rigid Dynamics and ANSYS Mechanical solvers, but are handled differently in certain circumstances by the two independent solvers. • For the ANSYS Rigid Dynamics solver the shock is considered as an event with no duration, during which the forces and accelerations are not known or available for postprocessing, but generate a relative velocity "jump". • For the ANSYS Mechanical solver the stop and lock constraints are implemented via the Lagrange Multiplier method. The constraint forces due to stop and lock conditions are available when stop is established

Coefficient of Restitution For the ANSYS Rigid Dynamics solver, Stops require you to set a coefficient of restitution value. This value represents the energy lost during the shock and is defined as the ratio between the joint’s relative velocity prior to the shock and the velocity following the shock. This value can be between 0 and 1. For a restitution value of zero, a Stop is released when the force in the joint is a traction force, while a Lock does not release. A restitution factor equal to 1 indicates that no energy is lost during the shock, that is, the rebounding velocity equals the impact velocity (a perfectly elastic collision). The coefficient of restitution is not applicable to the stops on the joints when using the ANSYS Mechanical solver. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Ease of Use Features The following ease of use features are available when defining joints: • Renaming Joint Objects Based on Definition (p. 594) • Joint Legend (p. 594) • Disable/Enable Transparency (p. 595) • Hide All Other Bodies (p. 595) • Flip Reference/Mobile (p. 596) • Joint DOF Checker (p. 596) • Redundancy Analysis (p. 596) • Model Topology (p. 596)

Renaming Joint Objects Based on Definition When joints are created, the Mechanical application automatically names each of the joint objects with a name that includes the type of joint followed by the names of the joined parts included as child objects under the Geometry object folder. For example, if a revolute joint connects a part named ARM to a part named ARM_HOUSING, then the object name becomes Revolute - ARM To ARM_HOUSING. The automatic naming based on the joint type and geometry definition is by default. You can however change the default from the automatic naming to a generic naming of Joint, Joint 2, Joint 3, and so on by choosing Tools> Options and under Connections, setting Auto Rename Connections to No. If you then want to rename any joint object based on the definition, click the right mouse button on the object and choose Rename Based on Definition from the context menu. You can rename all joints by clicking the right mouse button on the Joints folder then choosing Rename Based on Definition. The behavior of this feature is very similar to renaming manually created contact regions. See Renaming Contact Regions Based on Geometry Names (p. 532) for further details including an animated demonstration.

Joint Legend When you highlight a joint object, the accompanying display in the Geometry window includes a legend that depicts the free degrees of freedom characteristic of the type of joint. A color scheme is used to associate the free degrees of freedom with each of the axis of the joint's coordinate system shown in the graphic. An example legend is shown below for a slot joint.

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Joints

You can display or remove the joint legend using View> Legend from the main menu.

Disable/Enable Transparency The Enable Transparency feature allows you to graphically highlight a particular joint that is within a group of other joints, by rendering the other joints as transparent. The following example shows the same joint group presented in the Joint Legend (p. 594) section above but with transparency enabled. Note that the slot joint alone is highlighted.

To enable transparency for a joint object, click the right mouse button on the object and choose Enable Transparency from the context menu. Conversely, to disable transparency, click the right mouse button on the object and choose Disable Transparency from the context menu. The behavior of this feature is very similar to using transparency for highlighting contact regions. See Controlling Transparency for Contact Regions (p. 530) for further details including an animated demonstration.

Hide All Other Bodies You can hide all bodies except those associated with a particular joint. To use this feature, click the right mouse button on the object and choose Hide All Other Bodies from the context menu. Conversely, to show all bodies that may have been hidden, click the right mouse button on the object and choose Show All Bodies from the context menu.

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Flip Reference/Mobile For body-to-body joint scoping, you can reverse the scoping between the Reference and Mobile sides in one action. To use this feature, click the right mouse button on the object and choose Flip Reference/Mobile from the context menu. The change is reflected in the Details view of the joint object as well as in the color coding of the scoped entity on the joint graphic. The behavior of this feature is very similar to the Flip Contact/Target feature used for contact regions. See Flipping Contact and Target Scope Settings (p. 533) for further details including an animated demonstration.

Joint DOF Checker Once joints are created, fully defined, and applied to the model, a Joint DOF Checker calculates the total number of free degrees of freedom. The number of free degrees of freedom should be greater than zero in order to produce an expected result. If this number is less than 1, a warning message is displayed stating that the model may possibly be overconstrained, along with a suggestion to check the model closely and remove any redundant joint constraints. To display the Joint DOF Checker information, highlight the Connections object and click the Worksheet button. The Joint DOF Checker information is located just above the Joint Information heading in the worksheet.

Redundancy Analysis This feature allows you to analyze an assembly held together by joints. This analysis will also help you to solve over constrained assemblies. Each body in an assembly has a limited degree of freedom set. The joint constraints must be consistent to the motion of each body, otherwise the assembly can be locked, or the bodies may move in unwanted directions. The redundancy analysis checks the joints you define and indicates the joints that over constrain the assembly. To analyze an assembly for joint redundancies: 1.

Right-click the Connections object, and then select Redundancy Analysis to open a worksheet with a list of joints.

2.

Click Analyze to perform a redundancy analysis. All the over constrained joints are indicated as redundant.

3.

Click the Redundant label, and then select Fixed or Free to resolve the conflict manually. or Click Convert Redundancies to Free to remove all over constrained degrees of freedom.

4.

Click Set to update the joint definitions.

Note Click Export to save the worksheet to an Excel/text file.

Model Topology The Model Topology worksheet provides a summary of the joint connections between bodies in the model. This feature is a convenient way of verifying and troubleshooting a complex model that has many parts and joints. The Model Topology worksheet displays the connections each body has to other

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Joints bodies, and the joint through which these bodies are connected. Additional information for the joints is provided, including the joint type and the joint representation for the rigid body solver (i.e. whether the joint is based on degrees of freedom or constraint equations). To display the model topology, right-click on the Connections object, and then select Model Topology. The Model Topology worksheet displays in the Data View. The content of the worksheet can be exported as a text file using the Export button. Joints based on degrees of freedom are labeled either Direct or Revert in the Joint Direction column of the Model Topology table. Direct joints have their reference coordinate system on the ground side of the topology tree. Revert joints have their mobile coordinate system on the ground side. This information is useful for all post-processing based on python scripting, where internal data can be retrieved. For reverted joints, some of the joint internal results need to be multiplied by -1. Please refer to the ANSYS Rigid Dynamics Theory Manual for more information on model topology and selecting degrees of freedom.

Detecting Overconstrained Conditions Overconstrained conditions can occur when more constraints than are necessary are applied to a joint's degrees of freedom. These conditions may arise when rigid bodies are joined together using multiple joints. The overconstraints could be due to redundant joints performing the same function, or contradictory motion resulting from improper use of joints connecting different bodies. • For the Transient Structural analysis type, when a model is overconstrained, nonconvergence of the solution most often occurs, and in some cases, overconstrained models can yield incorrect results. • For the Rigid Dynamics analysis type, when a model is overconstrained, force calculation cannot be done properly. The following features exist within the Mechanical application that can assist you in detecting possible overconstrained conditions: • Use the Joint DOF Checker (p. 596) for detecting overconstrained conditions before solving (highlight Connections object and view the Worksheet). In the following example, the original display of the Joint DOF Checker warns that the model may be overconstrained.

After modifying the joint definitions, the user displays the Joint DOF Checker again, which shows that the overconstrained condition has been resolved.

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• After solution, you can highlight the Solution Information object, then scroll to the end of its content to view any information that may have been detected on model redundancies that caused overconstrained conditions. An example is presented below.

Mesh Connection The mesh connection feature allows you to join the meshes of topologically disconnected surface bodies that may reside in different parts. In the past, this process was done at the geometry level (for example, by using the DesignModeler application to repair small gaps). However, geometry tolerances are tighter than the tolerances used by mesh connections and often lead to problems in obtaining conformal mesh. With mesh connections, the connections are made at the mesh level and tolerance is based locally on mesh size. A connection can be edge-to-edge or edge-to-face. The mesh connection feature automatically generates post pinch controls internally at meshing time, allowing the connections to work across parts so that a multibody part is not required: • Edge-to-edge – Connect an edge on one face to edge(s) on another face to pinch out mesh/gap in between. • Edge-to-face – Connect edge(s) on face(s) to another face to pinch out the gap and create conformal mesh between the edge(s) and face(s). Although pinch controls can be pre or post, all mesh connections are post. “Post” indicates that the mesh is pinched in a separate step after meshing is complete, whereas in a “pre” pinch control, the boundary mesh is pinched prior to face mesh generation. Since mesh connections are a post mesh process, the base mesh is stored to allow for quicker updates. That is, if you change a mesh connection or meshing control, only local re-meshing is required to clean up the neighboring mesh. Surface Bodies With No Shared Topology:

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Mesh Connection

Same Surface Bodies With Edge-To-Edge Mesh Connection Established:

Enabling Mesh Connections To enable the mesh connection feature: 1. Insert Mesh Connection objects manually or automatically. • For more control, or to control the engineering design, you may want to insert mesh connections manually. • Alternatively, you can use automatic mesh connections, and then review and adjust each connection as appropriate. The automatic mesh connections feature is very helpful, but it can also find and create connections that you may not want. It is best practice to review the connections, or at least be aware that if problems arise, they may be due to automatic mesh connections. See Automatic Mesh Connection and Common Connections Folder Operations for Auto Generated Connections (p. 501) for details. 2. In the Details view specify Master Geometry and Slave Geometry. • “Master” indicates the topology that will be captured after the operation is complete. In other words, it is the topology to which other topologies in the connection are projected. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Setting Connections • “Slave” indicates the topology that will be pinched out during the operation. In other words, it is the topology that is projected to other topologies involved in the connection. The master geometry can be one or more faces or edges while the slave geometry can only be one or more edges. When specifying faces, the annotation is displayed on both sides of the faces.

Note Mesh connections support common imprints, which involve multiple slaves connected at the same location to a common master. See Common Imprints and Mesh Connections (p. 602).

3. In the Details view specify Tolerance. The Tolerance here has a similar meaning to the Tolerance Value global connection setting, and is represented as a transparent sphere. See Tolerances Used in Mesh Connections (p. 600) for details about Tolerance and how it relates to the Snap Tolerance described below. 4. For edge-to-face mesh connections only, in the Details view specify Snap to Boundary and Snap Type. When Snap to Boundary is Yes (the default) and the distance from a slave edge to the closest mesh boundary of the master face is within the specified snap to boundary tolerance, nodes from the slave edge are projected onto the boundary of the master face. The joined edge will be on the master face along with other edges on the master face that fall within the defined pinch control tolerance. See Pinch Control for details. Snap Type appears only when the value of Snap to Boundary is Yes. • If Snap Type is set to Manual Tolerance (the default), a Snap Tolerance field appears where you may enter a numerical value greater than 0. By default, the Snap Tolerance is set equal to the pinch tolerance but it can be overridden here. See Tolerances Used in Mesh Connections (p. 600) for details about Snap Tolerance and how it relates to the Tolerance described above. • If Snap Type is set to Element Size Factor, a Master Element Size Factor field appears where you may enter a numerical value greater than 0. The value entered should be a factor of the local element size of the master topology.

Note For edge-to-edge mesh connections (or edge-to-edge pinch controls), the snap tolerance is set equal to the pinch tolerance internally and cannot be modified.

5. Highlight the Mesh folder and choose Generate Mesh (right-click and choose from context menu). The surface bodies are displayed and show the mesh connections.

Tolerances Used in Mesh Connections You can set two separate tolerances to define mesh connections. Setting appropriate tolerances is often critical to obtaining high quality mesh that adequately represents the geometry you want to capture. • Tolerance – Projection tolerance to close gaps between bodies.

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Mesh Connection • Snap Tolerance – Snap to boundary tolerance to sew up mesh at the connection (applicable to edge-toface mesh connections only).

The Tolerance value is used to find which bodies should be connected to which other bodies. Setting a larger Tolerance connects more bodies together, while setting it smaller may cause some connections to be missed. For this reason, you may be motivated to set this to a larger value than needed. Setting a smaller value can avoid problems in automatic mesh connection creation, but also can result in other problems because the tolerance used in meshing is inherited from automatic mesh connection detection settings. Using a Large Tolerance Value For a large assembly for which you do not want to define mesh connections manually, automatic mesh connection detection provides many benefits. Setting a large Tolerance value to find connections yields more connections, which provides a higher level of comfort that the model is fully constrained. However, larger values can be problematic for the following reasons: • When more automatic mesh connections are created, more duplicates can be created and the mesher decides ultimately which connections to create. In general, making these decisions yourself is a better approach. • The Snap Tolerance defaults to the same value as the Tolerance. If the value of Tolerance is too large for Snap Tolerance, the mesher may be too aggressive in pinching out mesh at the connection, and hence the mesh quality and feature capturing may suffer. Using a Small Tolerance Value When mesh connections are generated automatically, the Tolerance is used on the geometry edges and faces to determine which entities should be connected. However, the connections themselves are not generated until meshing occurs. Because the connections are made on nodes and elements of the mesh rather than on the geometry, the tolerances do not translate exactly. For example, in the case below, you would want to set a Tolerance that is slightly larger than the gap in the geometry. If the gap is defined as x and the tolerance is set to x, automatic mesh connection detection could find the connection, but the meshing process may result in mesh that is only partially connected.

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Tips for Setting Tolerances As detailed above, setting the correct tolerance can be very important, and in some cases may require some speculation and/or experimentation. The following tips may help: • You can adjust the Tolerance used to generate automatic mesh connections after the connections are found. Sometimes it is a good idea to use one Tolerance value to find the mesh connections, select all the mesh connections, and then reduce or increase the Tolerance later. • Having Snap to Boundary turned on and using a Snap Tolerance are not always advisable. It depends on the model and the features you want to capture.

Mesh Sizing and Mesh Connections Mesh size has an effect on the quality and feature capture of a mesh connection as follows: • Mesh size always affects the base mesh, as features are only captured relative to mesh size. • During mesh connection processing, the base mesh is adjusted according to the common imprint/location. In cases where there is a large projection or a large difference in mesh sizes between the master entity and the slave entity, the common edge between bodies can become jagged. Also, as local smoothing takes place, there can be some problems in transition of element sizes. You can often use one of the following strategies to fix the problem: – Use more similar sizes between source and target. – Improve the tolerance used by mesh connections (either for projection, or for snapping to boundary). – Adjust the geometry's topology so that the base mesh is more accommodating to the mesh connection. See Common Imprints and Mesh Connections (p. 602).

Common Imprints and Mesh Connections The tolerance for common imprints comes from the minimum element size in the footprint mesh, which is the horizontal plate in the example below. Common imprints are made if the gap between imprints is smaller than or equal to the minimum element size in the connection region. For this reason, setting the mesh size appropriately is important to control whether the imprints will be common or not. For example, in the case shown below, if you want a common imprint, the minimum element size (or element size if Use Advanced Size Function is Off) should be > x.

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Mesh Connection In this case, you could scope local face mesh sizing on the horizontal plate to control the sizing.

Automatic Mesh Connection Mesh connections can be automatically generated using the Create Automatic Connections option available from the right-click context menu of the Connections or Connection Group folder. See Automatically Generated Connections for details. The Tolerance Value, pairing type and other properties used for auto detection can be set in the Details view of the Connection Group folder under the Auto Detection group. Sheet thickness can also be used as a tolerance value (see Common Connections Folder Operations for Auto Generated Connections (p. 501) for details).

Mesh Connections for Selected Bodies You can select a geometric entity and lookup the Mesh Connection object in the tree outline. To find the relevant mesh connection object: • Right-click a geometric entity, and then click Go To > Mesh Connections for Selected Bodies.

Mesh Connections Common to Selected Bodies You can select a pair of geometric entities and lookup the shared Mesh Connection object in the tree outline. To find a relevant mesh connection object: • Select the appropriate pair, and then click Go To > Mesh Connections Common to Selected Bodies. This option can be helpful for finding spurious mesh connections, in which case duplicates can be removed.

Displaying Multiple Views of Mesh Connections Use the Body Views button on the Connections Context Toolbar to display parts in separate auxiliary windows. For closer inspection of mesh connections, you can use the Show Mesh option on the Graphics Options Toolbar along with Body Views.

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Diagnosing Failed Mesh Connections General Failures In the event of a general mesh connection failure, the following approach is recommended: 1. If a message provides “Problematic Geometry” information, select the message, right-click, and select Show Problematic Geometry from the context menu. This action highlights the geometry in the Geometry window that is responsible for the message.

Note Any error message that is related to a specific mesh connection will be associated with the slave geometry in the connection.

2. Select the problematic bodies, right-click, and select Go To > Mesh Connections for Selected Bodies. This action highlights all mesh connections attached to the problematic geometry. 3. Review the tolerances and mesh sizes associated with the highlighted connections. Failures Due to Defeaturing from MultiZone Quad/Tri Meshing and/or Pinch Controls Due to the patch independent nature of the MultiZone Quad/Tri mesh method, a connection may fail because the mesh is associated with some face of the body but not with the face that is involved in the connection. This type of mesh connection failure, which may also occur when pinch controls are defined, is the result of the part mesh being significantly defeatured prior to mesh connection generation. To avoid mesh connection failures when using MultiZone Quad/Tri and/or pinch controls, use one of the following approaches: • Use virtual topology to merge the faces of interest with the adjacent faces to create large patches, and then apply mesh connections to the patches. • Protect small faces in mesh connections by defining Named Selections. 604

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Mesh Connection The software does not automatically extend the connection region because doing so may lose the engineering intent of the model. For example, consider the two parts shown below.

If you are using the MultiZone Quad/Tri mesh method or pinch controls, the part mesh may look like the one shown below. Notice that one face has been defeatured out.

In this case: • If the defeatured face is the one defined in the mesh connection, the connection will fail. • If the other face is the one defined in the mesh connection, the connection will succeed. • If you include both faces in the mesh connection, the connection will succeed. Since you cannot always control which face is defeatured, the most robust and recommended approach is to include both faces in the mesh connection.

Points to Remember • Toggling suppression of mesh connections or changing their properties causes bodies affected by those mesh connections to have an unmeshed state. However, when you subsequently select Generate Mesh, only the connections will be regenerated. Since mesh connections are a post mesh process, a re-mesh is not necessary and will not occur. • Mesh connections cannot be generated incrementally. Anytime you add or change mesh connections and select Generate Mesh, processing starts with the mesh in its unsewn (pre-joined) state and then re-sews the entire assembly. This approach is necessary as mesh connections often have interdependencies which can have a ripple effect through the assembly of parts. It is often the case that a connection must be reevaluated across the assembly as a single connection may invalidate many. • With mesh connections, you can mix and match mesh methods and/or use selective meshing. • When using selective meshing and you generate mesh, only out-of-date parts are re-meshed but all mesh connections are regenerated. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Setting Connections • Although the tolerance used for finding mesh connections and for generating mesh connections may be the same value, the tolerance itself has slightly different meanings in the two operations. When finding mesh connections, the tolerance is used to identify pairs of geometry edges or face(s)/edge(s). When generating mesh connections, the tolerance is used in pinching together the edge mesh or edge/face mesh. Since the geometry consists of NURBS, and the mesh consists of linear edges, the same tolerance may mean something slightly different in the two operations. For example, consider a geometry that consists of two cylindrical sheet parts that share an interface constructed from the same circle. Also consider that you are finding mesh connections with a tolerance of 0.0. In this case, the mesh connection is easily found because the two edges are exactly the same. However, when the mesh connection is being formed, some segments of the edge may fail to be pinched together if the mesh spacing of the two parts is different and thus the tolerance of the edge mesh is different. Also see Tolerances Used in Mesh Connections (p. 600). • For a higher order element, a midside node along the connection between a slave and a master is located at the midpoint between its end nodes, instead of being projected onto the geometry. • Although mesh connections do not alter the geometry, their effects can be previewed and toggled using the Graphics Options toolbar. • For the Shape Checking control, mesh connections support the Standard Mechanical option only. • If you define a mesh connection on topology to which a match control, mapped face meshing control, or inflation control (global or local) is already applied, a warning will be issued when you generate the mesh. The warning will indicate that the mesh connection may alter the mesh, which in turn may eliminate or disable the match, mapped face meshing, or inflation control. • Mesh connections and post pinch controls cannot be mixed with refinement or post inflation controls. • A mesh connection scoped to geometries (for the master and the slave) that lie on the same face are ignored by the mesher, and, as a result, no mesh extension is generated. • Refer to Clearing Generated Data for information about using the Clear Generated Data option on parts and bodies that have been joined by mesh connections or post pinch controls. • Refer to Using the Mesh Worksheet to Create a Selective Meshing History for information about how mesh connection operations are processed by the Mesh worksheet.

Springs A spring is an elastic element that is used to store mechanical energy and which retains its original shape after a force is removed. Springs are typically defined in a stress free or “unloaded” state. This means that no longitudinal loading conditions exist unless preloading is specified (see below). In Mechanical, the Configure feature is used to modify a Joint. If you configure a joint that has an attached spring, the spring must be redrawn in the Geometry window. In effect, the spring before the Configure action is replaced by a new spring in a new unloaded state. Springs are defined as longitudinal and they connect two bodies together or connect a body to ground. Longitudinal springs generate a force that depends on linear displacement. Longitudinal springs can

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Springs be used as a damping force, which is a function of velocity or angular velocity, respectively. Springs can also be defined directly on a Revolute Joint (p. 546) or a Cylindrical Joint (p. 546).

Note A spring cannot be applied to a vertex that is scoped to an end release. Springs are not supported for Explicit Dynamics (LS-DYNA Export) systems. The following topics are discussed in this section: • Applying Springs (p. 607) • Spring Behavior (p. 608) • Nonlinear Spring Stiffness (p. 610) • Preloading (p. 610) • Scoping (p. 611) • Spring Length (p. 611) • Advanced Features (p. 611) • Output (p. 612) • Example: Longitudinal Spring with Damping (p. 612) • Spring Incompatibility (p. 614)

Applying Springs To apply a spring: 1.

After importing the model, highlight the Model object in the tree and choose the Connections button from the toolbar.

2.

Highlight the new Connections object and choose either Body-Ground>Spring or Body-Body>Spring from the toolbar, as applicable. (Body-Ground springs are not supported for explicit dynamics analyses.)

Note You can pre-select a vertex or node (Body-Ground) or two vertices or nodes (BodyBody) and then insert a Spring to automatically create a directly attached spring. See the Scoping subsection below.

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Highlight the new Spring object and enter information in the Details view. Note that Longitudinal Damping is applicable only to transient analyses.

Note The length of the spring connection must be greater than 0.0 with a tolerance of 1e-8 mm.

Spring Behavior The Spring Behavior property is modifiable for a Rigid Dynamics and Explicit Dynamics analyses only. For all other analysis types, this field is read-only and displays as Both. You can define a longitudinal spring to support only tension loads or only compression loads using the Spring Behavior property. You can set this property to Both, Compression Only or Tension Only. The tension only spring does not provide any restoring force against compression loads. The compression only spring does not provide resistance against tensile loads. The stiffness of a compression only or tension only spring without any preloads is shown below. Stiffness Behavior of a Tension Only Spring:

Stiffness Behavior of a Compression Only Spring:

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Springs

Force Deflection Curve for a Tension Only Spring:

Force Deflection Curve for a Compression Only Spring:

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Nonlinear Spring Stiffness A nonlinear force-deflection curve can be used to simulate multi-rate springs with nonlinear spring stiffness. A linear piecewise curve is used for this purpose. Note that spring deflection is computed using the distance between the two ends of the spring, minus the initial length. The distance between the two points is never negative, but the deflection can be negative. If you determine that a spring exists with an incorrectly defined nonlinear stiffness, the forcedeflection curve may be incorrectly defined as a result of the tabular input for nonlinear stiffness for one or more spring objects. See the details in COMBIN39 element description for more information.

Note Support Requirements • Tabular Data requires at least two rows of data. • The properties Longitudinal Damping and Preload are not applicable for Springs with nonlinear stiffness.

Points to consider for Rigid Dynamics or Explicit Dynamics analyses only: • If a nonlinear stiffness curve is defined with the Tension Only option, all points with a negative displacement are ignored. • If a nonlinear stiffness curve is defined with the Compression Only option, all points with a positive displacement are ignored. To define a nonlinear force-deflection curve: 1.

In the Spring object Details view settings, click in the Longitudinal Stiffness property.

2.

Click the arrow in the Longitudinal Stiffness property then select Tabular.

3.

Enter displacement and force values in the Tabular Data window. A graph showing force vs. displacement is displayed.

Preloading (Not supported for explicit dynamics analyses.) Mechanical also provides you with the option to preload a spring and create an initial “loaded” state. The Preload property in the Details view allows you to define a preload as a length using Free Length or to specify a specific Load. The actual length is calculated using spring end points from the Reference and Mobile scoping. For rigid dynamics analyses, the spring will be under tension or compression depending upon whether you specified the free length as smaller or greater than the spring length, respectively. If preload is specified in terms of Load, a positive value creates tension and a negative value creates compression. When the spring is linear (defined by a constant stiffness) the Rigid Dynamics solver deduces the spring freelength by subtracting the value L=F/K (where F is the preload and K is the stiffness) from the actual spring length. Note that this offset is also applied to the elongation results. When the spring is non-linear (defined by a force/displacement table), this offset is not taken into account.

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Springs

Spring Length The read-only property Spring Length displays the actual length of the spring which is calculated using the end points from the Reference and Mobile scoping.

Scoping You select the Scope of springs as body-to-body or body-to-ground using the property of the Scope category and you define a spring’s end points using the properties of the Reference and Mobile categories. For body-to-ground property specification, the Reference is assumed to be grounded (fixed); scoping is only available on the Mobile side. Since this is a unidirectional spring, these two locations determine the spring’s line of action and as such the spring’s reference and mobile locations cannot be the same as this would result in a spring with zero length. In addition, the Reference and Mobile categories provide the scoping property Applied By. This property allows you to specify the connection as either a Direct Attachment or a Remote Attachment. The Remote Attachment option (default) uses a Remote Point as a scoping mechanism. The Direct Attachment option allows you to scope directly to a single vertex or a node of the model.

Note If specified as a Remote Attachment, springs are classified as remote boundary conditions. Refer to the Remote Boundary Conditions (p. 833) section for a listing of all remote boundary conditions and their characteristics. You can scope of a spring to a: • Single face or to multiple faces (applied as a Remote Attachment only). • Single edge or multiple edges (applied as a Remote Attachment only). • Single vertex (can be applied as either a Remote Attachment or as a Direct Attachment) or multiple vertices (applied as a Remote Attachment only).

Note A spring cannot be applied to a vertex that is scoped to an end release.

• Single node (applied as a Direct Attachment only). See the Spring Object Reference page of the Help for additional information about the available categories and properties.

Advanced Features If specified as a Remote Attachment, the Reference and Mobile groups for Springs each include the following advanced properties: • Behavior - This property allows you to specify the scoped geometry as either Rigid or Deformable. Refer to the Geometry Behaviors and Support Specifications (p. 464) section for more information.

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Setting Connections • Pinball Region - This property allows you to specify the contact search size.

Note The Behavior setting is applicable to underlying bodies that are flexible.

Output Several outputs are available via a spring probe.

Example: Longitudinal Spring with Damping This example shows the effect of a longitudinal spring connecting a rectangular bar to ground to represent a damper. A Transient Structural analysis was performed in the environment shown:

The following are the Details view settings of the Spring object:

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Springs

Presented below is the Total Deformation result: The following demo is presented as an animated GIF. Please view online if you are reading the PDF version of the help. Interface names and other components shown in the demo may differ from those in the released product.

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Setting Connections

Spring Incompatibility (applicable only to rigid dynamics analyses) If the preload for a longitudinal spring is a tensile load, then the spring cannot be defined as compression only. Alternatively, if the preload is a compressive load, then the spring cannot be defined as tension only. Should this case occur, the spring will be marked as underdefined and if you attempt to solve such a case, the following error message is displayed: “The preload for a spring is incompatible with its behavior being tension only spring or compression only spring.”

Beam Connections A beam is a structural element that carries load primarily in bending (flexure). Using the Beam feature, you can establish a body-to-body or a body-to-ground connections. You can use beams for all structural analyses. To add a Beam object: 1. Select the Connections folder in the object tree. As needed, add a Connections folder by selecting the Model object and clicking the Connections button on the Model Context Toolbar. 2. On the Connections Context Toolbar, click Body-Ground or Body-Body and then click Beam to add a circular beam under connections. 3. In the Details View, under Definition, click the Material fly-out menu, and then select a material for the beam. 4. Enter a beam radius in the Radius field. 5. If necessary, modify the Scope setting. The Scope property of the Scope category allows you to change the scoping from Body-Body to Body-Ground. Similar to Springs, this property defines the beam’s end points in coordination with the properties of the Reference and Mobile categories. For body-to-ground property specification, the Reference is assumed to be grounded (fixed) and as a result scoping is required on the Mobile side only. Because beam’s define a span, the reference and mobile locations determine a distance and as such the reference and mobile locations cannot be the same. In addition, the Reference and Mobile categories provide the scoping property Applied By. This property allows you to specify the connection as either a Direct Attachment or a Remote Attachment. The Remote Attachment option (default) uses a Remote Point as a scoping mechanism. The Direct Attachment option allows you to scope directly to a single vertex or a node of the model. Direct Attachment is not allowed if scoped to solid bodies, as they do not have rotational degrees of freedom. 6. Under the Reference category, for Body-Body connections only: a. Specify the Scoping Method property as either Geometry Selection, Named Selection, or Remote Point. Based on the selection made in this step, select a: • geometry (faces, edges, or vertices) and click Apply in the Scope property field. or...

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Beam Connections • single node (Direct Attachment Only) and click Apply in the Scope property. In order to select an individual node, you need to first generate a mesh on the model, and then choose the Show Mesh button on the Graphics Options Toolbar, and then specify Select Mesh as the Select Type from the Graphics Toolbar. or... • user-defined node-based named selection (Direct Attachment Only) or a user-defined geometrybased named selection (Remote Attachment Only) from the drop-down list of the Named Selection property. or... • user-defined remote point (Remote Attachment Only) from the drop-down list of the Remote Point property.

Note You can pre-select a vertex or node (Body-Ground) or two vertices or nodes (BodyBody) and then insert a Beam to automatically create a directly attached beam.

7. Specify the following properties as needed. These properties are available under the Reference Category (Body-Body or Body-Ground connections) when the Applied By property is set to Remote Attachment: • Coordinate System: select a different coordinate system if desired. • Reference X Coordinate: enter a value as needed. • Reference Y Coordinate enter a value as needed. • Behavior: specify this property as either Rigid or Deformable. Refer to the Geometry Behaviors and Support Specifications section for more information. • Pinball Radius: enter a value as needed. 8. Under Mobile Category (Body-Body or Body-Ground connections): a. Specify the Scoping Method property as either Geometry Selection, Named Selection, or Remote Point. Based on the selection made in this step, select a: • geometry (faces, edges, or vertices) and click Apply in the Scope property field. or... • single node (Direct Attachment Only) and click Apply in the Scope property. In order to select an individual node, you need to first generate a mesh on the model, and then choose the Show Mesh button on the Graphics Options Toolbar, and then specify Select Mesh as the Select Type from the Graphics Toolbar. or... • user-defined node-based named selection (Direct Attachment Only) or a user-defined geometrybased named selection (Remote Attachment Only) from the drop-down list of the Named Selection property. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Setting Connections or... • user-defined remote point (Remote Attachment Only) from the drop-down list of the Remote Point property. b. Specify the following properties as needed. These properties are available under the Mobile Category (Body-Body or Body-Ground connections) when the Applied By property is set to Remote Attachment: • Coordinate System: select a different coordinate system if desired. • Mobile X Coordinate: enter a location value. • Mobile Y Coordinate enter a location value. • Behavior: specify this property as either Rigid or Deformable. Refer to the Geometry Behaviors and Support Specifications section for more information. • Pinball Radius: enter a dimension value. See the Beam Object Reference page of the Help for additional information about the available categories and properties.

Note • For Body-Ground beam connections, the reference side is fixed. For Body-Body beam connections, you must define the reference point for each body. • The length of the beam connection must be greater than 0.0 with a tolerance of 1e-8 mm. • Beam connections support structural analyses only. In thermal stress analyses, beam connections are assigned the environment temperature in the structural analysis. You can include a beam in a thermal analysis by creating a line body and as a result providing for temperature transference.

The Beam Probe results provide you the forces and moments in the beam from your analysis.

Spot Welds Spot welds are used to connect individual surface body parts together to form surface body model assemblies, just as a Contact Region is used for solid body part assemblies. Structural loads are transferred from one surface body part to another via the spot weld connection points, allowing for simulation of surface body model assemblies.

Spot Weld Details Spot welds are usually defined in the CAD system and automatically generated upon import, although you can define them manually in the Mechanical application after the model is imported. Spot welds then become hard points in the geometric model. Hard points are vertices in the geometry that are linked together using beam elements during the meshing process.

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Spot Welds Spot weld objects are located in a Connection Group folder. When selected in the tree, they appear in the graphical window highlighted by a black square around a white dot on the underlying vertices, with an annotation. If a surface body model contains spot weld features in the CAD system and the Auto Detect Contact On Attach is turned on in Workbench Tools>Options>Mechanical, then Spot Weld objects are generated when the model is read into the Mechanical application. Spot weld objects will also get generated during geometry refresh if the Generate Automatic Connection On Refresh is set to Yes in the Details view of the Connections folder. This is similar to the way in which the Mechanical application automatically constructs contacts when reading in assemblies models and refreshing the geometry. You can manually generate spot welds as you would insert any new object into the Outline tree. Either insert a spot weld object from the context menu and then pick two appropriate vertices in the model, or pick two appropriate vertices and then insert the spot weld object. You can define spot welds for CAD models that do not have a spot weld feature in the CAD system, as long as the model contains vertices at the desired locations. You must define spot welds manually in these cases.

Spot Weld Application Spot welds do not act to prevent penetration of the connected surface body in areas other than at the spot weld location. Penetration of the joined surface body is possible in areas where spot welds do not exist. Spot welds transfer structural loads and thermal loads as well as structural effects between solid, surface, and line body parts. Therefore they are appropriate for displacement, stress, elastic strain, thermal, and frequency solutions. DesignModeler generates spot welds. The only CAD system whose spot welds can be fully realized in ANSYS Workbench at this time is NX. The APIs of the remaining CAD systems either do not handle spot welds, or the ANSYS Workbench software does not read spot welds from these other CAD systems.

Spot Welds in Explicit Dynamics Analyses Spot welds provide a mechanism to rigidly connect two discrete points in a model and can be used to represent welds, rivets, bolts etc. The points usually belong to two different surfaces and are defined on the geometry (see DesignModeler help). During the solver initialization process, the two points defining each spot weld will be connected by a rigid beam element. Additionally, rigid beam elements will be generated on each surface to enable transfer of rotations at the spot weld location (see figure below). If the point of the spot weld lies on a shell body, both translational and rotational degrees of freedom will be linked at the connecting point. If the point of the spot weld lies on a the surface of a solid body, additional rigid beam elements will be generated to enable transfer of rotations at the spot weld location. Spot welds can be released during a simulation using the Breakable Stress or Force option. If the stress criteria is selected the user will be asked to define an effective cross sectional area. This is used to convert the defined stress limits into equivalent force limits. A spot weld will break (release) if the following criteria is exceeded

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Setting Connections Where: fn and fs are normal and shear interface forces Sn and Ssare the maximum allowed normal and shear force limits n and s are user defined exponential coefficients Not that the normal interface force fn is non-zero for tensile values only. After failure of the spot weld the rigid body connecting the points is removed from the simulation. Spot welds of zero length are permitted. However, if such spot welds are defined as breakable the above failure criteria is modified since local normal and shear directions cannot be defined. A modified criteria is used with global forces

Where,

are the force differences across the spot weld in the global coordinate system.

Note A spot weld is equivalent to a rigid body and as such multiple nodal boundary conditions cannot be applied to spot welds.

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Body Interactions in Explicit Dynamics Analyses

End Releases This feature allows you to release certain degrees of freedoms at a vertex shared by two or more edges of one or more line bodies, by using an End Release object. You can only apply one end release at the vertex and the edge must be connected to another edge at this vertex. To add an End Release: 1. Add a Connections folder if one is not already in the tree, by highlighting the Model object and choosing Connections from the Model Context Toolbar (p. 55) or by choosing Insert >Connections from the context menu (right-click). 2. Add an End Release object by highlighting the Connections folder and choosing End Release from the Connections Context Toolbar (p. 57) or by choosing Insert >End Release from the context menu (rightclick). 3. Set the following in the Details view: a. Scoping Method as Geometry Selection (default) or Named Selection. b. Edge Geometry and Vertex Geometry, respectively. The vertex should be one of the two end vertices of the edge. c. Coordinate System as the Global Coordinate System or a local coordinate system that you may have defined previously. d. Release any of the translational and/or rotational degrees of freedoms in X, Y and Z directions by changing the individual settings from Fixed to Free. e. Connection Behavior as either Coupled (default) or Joint, using a coupling or a general joint, respectively.

Notes • The end release feature is only applicable in structural analyses that use the ANSYS solver. The environment folder of other solvers will become underdefined when one or more End Release objects are present. • An end release object requires that the vertex must be on an edge and it should be shared with one or more other edges or one or more surface bodies. • A vertex cannot be scoped to more than one end release object. • The following boundary conditions are not allowed to be applied to a vertex or an edge that is already scoped to an end release The object will become underdefined with an error message: Fixed Support, Displacement, Simply Supported, Fixed Rotation, Velocity. • The following remote boundary conditions are not allowed to be applied to a vertex scoped to an end release The object will become underdefined with an error message: Remote Displacement, Remote Force, Moment, Point Mass, Thermal Point Mass, Spring, Joint.

Body Interactions in Explicit Dynamics Analyses Within an explicit dynamics analysis, the body interaction feature represents contact between bodies and includes settings that allow you to control these interactions. If the geometry you use has two or Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Setting Connections more bodies in contact, a Body Interactions object folder appears by default under Connections in the tree. Included in a Body Interactions folder are one or more Body Interaction objects, with each object representing a contact pair. You can also manually add these two objects: • To add a Body Interactions folder, highlight the Connections folder and choose Body Interactions from the toolbar. A Body Interactions folder is added and includes one Body Interaction object. • To add a Body Interaction object to an existing Body Interactions folder, highlight the Connections folder, the Body Interactions folder, or an existing Body Interaction object, and choose Body Interaction from the toolbar.

General Notes Each Body Interaction object activates an interaction for the bodies scoped in the object. With body interactions, contact detection is completely automated in the solver. At any time point during the analysis any node of the bodies scoped in the interaction may interact with any face of the bodies scoped in the interaction. The interactions are automatically detected during the solution. The default frictionless interaction type that is scoped to all bodies activates frictionless contact between any external node and face that may come into contact in the model during the analysis. To improve the efficiency of analyses involving large number of bodies, you are advised to suppress the default frictionless interaction that is scoped to all bodies, and instead insert additional Body Interaction objects which limit interactions to specific bodies. The union of all frictional/frictionless body interactions defines the matrix of possible body interactions during the analysis. For example, in the model shown below: • Body A is traveling towards body B and we require frictional contact to occur. A frictional body interaction type scoped only to bodies A and B will achieve this. Body A will not come close to body C during the analysis so it does not need to be included in the interaction. • Body B is bonded to body C. A bonded body Interaction type, scoped to bodies B and C will achieve this. • If the bond between bodies B and C breaks during the analysis, we want frictional contact to take place between bodies B and C. A frictional body interaction type scoped only to bodies B and C will achieve this.

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Body Interactions in Explicit Dynamics Analyses

A bonded body interaction type can be applied in addition to a frictional/frictionless body interaction. A reinforcement body interaction type be can be applied in addition to a frictional/frictionless body interaction. Object property settings are included in the Details view for both the Body Interactions folder and the individual Body Interaction objects. Refer to the following sections for descriptions of these properties. Properties for Body Interactions Folder Interaction Type Properties for Body Interaction Object Identifying Body Interactions Regions for a Body

Properties for Body Interactions Folder All properties for the Body Interactions folder are included in an Advanced category and define the global properties of the contact algorithm for the analysis. These properties are applied to all Body Interaction objects and to all frictional and frictionless manual contact regions. This section includes descriptions of the following properties for the Body Interactions folder: Contact Detection Formulation Shell Thickness Factor Body Self Contact Element Self Contact Tolerance Pinball Factor Time Step Safety Factor Limiting Time Step Velocity Edge on Edge Contact

Contact Detection The available choices are described below.

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Setting Connections

Trajectory The trajectory of nodes and faces included in frictional or frictionless contact are tracked during the computation cycle. If the trajectory of a node and a face intersects during the cycle a contact event is detected. The trajectory contact algorithm is the default and recommended option in most cases for contact in Explicit Dynamics analyses. Contacting nodes/faces can be initially separated or coincident at the start of the analysis. Trajectory based contact detection does not impose any constraint on the analysis time step and therefore often provides the most efficient solution.

Note Trajectory Contact Detection is not supported for a distributed solve. If you would like to use Trajectory Contact Detection for a distributed solve, please contact ANSYS Technical Support. Note that nodes which penetrate into another element at the start of the simulation will be ignored for the purposes of contact and thus should be avoided. To generate duplicate conforming nodes across a contact interface: 1. Use the multibody part option in DesignModeler and set Shared Topology to Imprint. 2. For meshing, use Contact Sizing, the Arbitrary match control or the Match mesh Where Possible option of the Patch Independent mesh method.

Proximity Based The external faces, edges and nodes of a mesh are encapsulated by a contact detection zone. If during the analysis a node enters this detection zone, it will be repelled using a penalty based force.

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Body Interactions in Explicit Dynamics Analyses

Note • An additional constraint is applied to the analysis time step when this contact detection algorithm is selected. The time step is constrained such that a node cannot travel through a fraction of the contact detection zone size in one cycle. The fraction is defined by the Time Step Safety Factor (p. 626) described below. For analyses involving high velocities, the time step used in the analysis is often controlled by the contact algorithm. • The initial geometry/mesh must be defined such that there is a physical gap/separation of at least the contact detection zone size between nodes and faces in the model. The solver will give error messages if this criteria is not satisfied. This constraint means this option may not be practical for very complex assemblies. • Proximity Based Contact is not supported in 2D explicit dynamics analyses.

Formulation This property is available if Contact Detection is set to Trajectory. The available choices are described below.

Penalty If contact is detected, a local penalty force is calculated to push the node involved in the contact event back to the face. Equal and opposite forces are calculated on the nodes of the face in order to conserve linear and angular momentum.

Trajectory based penalty force,

Proximity based penalty force, Where: D is the depth of penetration M is the effective mass of the node (N) and face (F)

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Setting Connections ∆t is the simulation time step

Note • Kinetic energy is not necessarily conserved. You can track conservation of energy in contact using the Solution Information object, the Solution Output, or one of the energy summary result trackers. • The applied penalty force will push the nodes back towards the true contact position during the cycle. However, it will usually take several cycles to satisfy the contact condition.

Decomposition Response All contacts that take place at the same point in time are first detected. The response of the system to these contact events is then calculated to conserve momentum and energy. During this process, forces are calculated to ensure that the resulting position of nodes and faces does not result in further penetration at that time point.

Note • The decomposition response algorithm cannot be used in combination with bonded contact regions. The formulation will be automatically switch to penalty if bonded regions are present in the model. • The decomposition response algorithm is more impulsive (in a given cycle) than the penalty method. This can give rise to large hourglass energies and energy errors.

Shell Thickness Factor This property is available if the geometry includes one or more surface bodies and if Contact Detection is set to Trajectory. The Shell Thickness Factor allows you to control the effective thickness of surface bodies used in the contact. You can specify a value between 0.0 and 1.0. • A value of 0.0 means that contact will ignore the physical thickness of the surface body and the contact surface will be coincident with the mid-plane of the shell • A value of 1.0 means that the contact shell thickness will be equal to the physical shell thickness. The contact surface will be offset from the mid-plane of the shell by half the shell thickness (on both sides of the shell)

Note Only node to surface contact is currently supported. For shell to shell contact, this means that contact takes place when the shell node impacts the shell contact surface as described above.

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Body Interactions in Explicit Dynamics Analyses

Body Self Contact When set to Yes, the contact detection algorithm will check for external nodes of a body contacting with faces of the same body in addition to other bodies. This is the most robust option since all possible external contacts should be detected. When set to No, the contact detection algorithm will only check for external nodes of a body contacting with external faces of other bodies. This setting reduces the number of possible contact events and can therefore improve efficiency of the analysis. This option should not be used if a body is likely to fold onto itself during the analysis, as it would during plastic buckling for example. When set to Program Controlled, the behavior of self contact is determined by the Analysis Settings Preference Type. Presented below is an example of a model that includes self impact.

Element Self Contact When set to Yes, automatic erosion (removal of elements) is enabled when an element deforms such that one of its nodes comes within a specified distance of one of its faces. In this situation, elements are removed before they become degenerated. Element self contact is very useful for impact penetration examples where removal of elements is essential to allow generation of a hole in a structure.

When set to Program Controlled, the behavior of self contact is determined by the Analysis Settings Preference Type.

Tolerance This property is available if Contact Detection is set to Trajectory and Element Self Contact is set to Yes.

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Setting Connections Tolerance defines the size of the detection zone for element self contact when the trajectory contact option is used. (see Element Self Contact (p. 625)). The value input is a factor in the range 0.1 to 0.5. This factor is multiplied by the smallest characteristic dimension of the elements in the mesh to give a physical dimension. A setting of 0.5 effectively equates to 50% of the smallest element dimension in the model.

Note The smaller the fraction the more accurate the solution.

Pinball Factor This property is available if Contact Detection is set to Proximity Based. The pinball factor defines the size of the detection zone for proximity based contact. The value input is a factor in the range 0.1 to 0.5. This factor is multiplied by the smallest characteristic dimension of the elements in the mesh to give a physical dimension. A setting of 0.5 effectively equates to 50% of the smallest element dimension in the model.

Note The smaller the fraction the more accurate the solution. The time step in the analysis could be reduced significantly if small values are used (see Time Step Safety Factor (p. 626)).

Time Step Safety Factor This property is available if Contact Detection is set to Proximity Based. For proximity based contact, the time step used in the analysis is additionally constrained by contact such that in one cycle, a node in the model cannot travel more than the detection zone size, multiplied by a safety factor. The safety factor is defined with this property and the recommended default is 0.2. Increasing the factor may increase the time step and hence reduce runtimes, but may also lead to missed contacts. The maximum value you can specify is 0.5.

Limiting Time Step Velocity This property is available if Contact Detection is set to Proximity Based. For proximity based contact, this setting limits the maximum velocity that will be used to compute the proximity based contact time step calculation.

Edge on Edge Contact This property is available if Contact Detection is set to Proximity Based.

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Body Interactions in Explicit Dynamics Analyses By default, contact events in explicit dynamics are detected by discrete nodes impacting surface events. Use this option to extend the contact detection to include discrete edges impacting other edges in the model.

Note this option is numerically intensive and can significantly increase runtimes. It is recommended that you compare results with and without edge contact to make sure this feature is required.

Interaction Type Properties for Body Interaction Object This section includes descriptions of the interaction types for the Body Interaction object: Frictionless Type Frictional Type Bonded Type Reinforcement Type

Frictionless Type Setting Type to Frictionless activates frictionless sliding contact between any exterior node and any exterior face of the scoped bodies. Individual contact events are detected and tracked during the analysis. The contact is symmetric between bodies (that is, each node will belong to a master face impacted by adjacent slave nodes; each node will also act as a slave impacting a master face).

Supported Connections Explicit Dynamics Connection Geometry

Volume

Shell

Line

Volume

Yes

Yes

Yes

Shell

Yes

Yes

Yes

Line

Yes

Yes

*Yes

*Only for Contact Detection = Proximity Based and Edge on Edge Contact = Yes (This option switches on contact between ALL lines / bodies / edges, that is, there is no dependence on the scoping selection of body interactions.) Explicit Dynamics (LS-DYNA Export) Connection Geometry

Volume

Shell

Line

Volume

Yes

Yes

No

Shell

Yes

Yes

No

Line

No

No

No

Frictional Type Descriptions of the following properties are also addressed in this section: • Friction Coefficient

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Setting Connections • Dynamic Coefficient • Decay Constant Setting Type to Frictional activates frictional sliding contact between any exterior node and any exterior face of the scoped bodies. Individual contact events are detected and tracked during the simulation. The contact is symmetric between bodies (that is, each node will belong to a master face impacted by adjacent slave nodes, each node will also act as a slave impacting a master face). Friction Coefficient: A non-zero value will activate Coulomb type friction between bodies (F = µR). The relative velocity (ν) of sliding interfaces can influence frictional forces. A dynamic frictional formulation for the coefficient of friction can be used. µ = µd + (µs – µd) e-βν where µs = friction coefficient µd = dynamic coefficient of friction β = exponential decay coefficient ν = relative sliding velocity at point of contact Non-zero values of the Dynamic Coefficient and Decay Constant should be used to apply dynamic friction.

Supported Connections Explicit Dynamics Connection Geometry

Volume

Shell

Line

Volume

Yes

Yes

Yes

Shell

Yes

Yes

Yes

Line

Yes

Yes

*Yes

*Only for Contact Detection = Proximity Based and Edge on Edge Contact = Yes (This option switches on contact between ALL lines / bodies / edges, that is, there is no dependence on the scoping selection of body interactions.) Explicit Dynamics (LS-DYNA Export) Connection Geometry

Volume

Shell

Line

Volume

Yes

Yes

No

Shell

Yes

Yes

No

Line

No

No

No

Bonded Type Descriptions of the following properties are also addressed in this section: 628

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Body Interactions in Explicit Dynamics Analyses • Maximum Offset • Breakable – Stress Criteria → Normal Stress Limit → Normal Stress Exponent → Shear Stress Limit → Shear Stress Exponent External nodes of bodies included in bonded interactions will be tied to faces of bodies included in the interaction if the distance between the external node and the face is less than the value (tolerance) defined by the user in Maximum Offset. The solver automatically detects the bonded nodes/faces during the initialization phase of the analysis. Note that it is important to select an appropriate value for the Maximum Offset (tolerance). The automatic search will bond everything together which is found within this value (tolerance). Use the custom variable BOND_STATUS to check bonded connections in Explicit Dynamics. The variable records the number of nodes bonded to the faces on an element during the analysis. This can be used not only to verify that initial bonds are generated appropriately, but also to identify bonds that break during the simulation. Maximum Offset defines the tolerance used at initialization to determine whether a node is bonded to a face. Breakable = No implies that the bond will remain throughout the analysis. Breakable = Stress Criteria implies that the bond may break (or be released) during the analysis. The criteria for breaking a bond is defined as: (σn/σnlim it)n + (|σs|/σslim it)m > or equal to 1 where σnlim it = Normal Stress Limit n = Normal Stress Exponent σslim it = Shear Stress Limit m = Shear Stress Exponent The options in the Advanced section are all currently ignored by the Explicit solver, including the Advanced > Pinball region option. The tolerance must be defined via the Maximum Offset value and is only used at initialization.

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Setting Connections Connection Geometry

Volume

Shell

Line

Volume

Yes

Yes

Yes

Shell

Yes

Yes

Yes

Line

Yes

Yes

Yes

Note Bonded body interactions and contact are not supported for 2D Explicit Dynamics analyses. Explicit Dynamics (LS-DYNA Export)* Connection Geometry

Volume

Shell

Line

Volume

Yes

Yes

No

Shell

Yes

Yes

No

Line

Yes

Yes

No

*The above matrix is valid only for Contact Regions. Bonded body interactions are not supported at all.

Reinforcement Type This body interaction type is used to apply discrete reinforcement to solid bodies. All line bodies scoped to the object will be flagged as potential discrete reinforcing bodies in the solver. On initialization of the solver, all elements of the line bodies scoped to the object which are contained within any solid body in the model will be converted to discrete reinforcement. Elements which lie outside all volume bodies will remain as standard line body elements. The reinforcing beam nodes will be constrained to stay at the same initial parametric location within the volume element they reside during element deformation. Typical applications involve reinforced concrete or reinforced rubber structures likes tires and hoses. If the volume element to which a reinforcing node is tied is eroded, the beam node bonding constraint is removed and becomes a free beam node. On erosion of a reinforcing beam element node, if inertia is retained, the node will remain tied to the parametric location of the volume element. If inertia is not retained, the node will also be eroded

Note Volume elements that are intersected by reinforcement beams, but do not contain a beam node, will not be experiencing any reinforced beam forces. Good modeling practice is

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Body Interactions in Explicit Dynamics Analyses therefore to have the element size of the beams similar or less than that of the volume elements. Table 3: Example: Drop test onto reinforced concrete beam

Note that the target solid bodies do not need to be scoped to this object – these will be identified automatically by the solver on initialization.

Supported Connections Explicit Dynamics Connection Geometry

Volume

Shell

Line

Volume

No

No

*Yes

Shell

No

No

No

Line

*Yes

No

No

*Only the line body needs to be included in the scope. The ANSYS AUTODYN solver automatically detects which volume bodies that the line body passes through.

Note Reinforcement body interactions are not supported for 2D Explicit Dynamics analyses. Explicit Dynamics (LS-DYNA Export) Connection Geometry

Volume

Shell

Line

Volume

No

No

No

Shell

No

No

No

Line

No

No

No

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Setting Connections

Identifying Body Interactions Regions for a Body See the description for Body Interactions for Selected Bodies in the section Correlating Tree Outline Objects with Model Characteristics (p. 6).

Bearings A bearing is a two-dimensional elastic element used to confine relative motion and rotation of a rotating machinery part. Bearings are a critical support for Rotordynamics analyses and as such, a good bearing design is essential to ensure stability of machinery parts under high speed rotations. Similar to a spring, a bearing has the structural characteristics of longitudinal stiffness and damping. In addition to these characteristics, bearings are enhanced with coupling stiffness and damping that serve as resistive forces to movement of the machinery part in a rotation plane. Bearings are supported by all Mechanical analysis types that use the MAPDL solver.

Note • The damping characteristics are not applicable to static, linear buckling, undamped modal, and spectrum analysis systems. • While negative stiffness and/or damping characteristics are allowed in all the supported analysis systems, users are cautioned to ensure its proper use, and check the results carefully. • This boundary condition cannot be applied to a vertex scoped to an End Release.

Scoping Requirements Bearing scoping is limited to only a single face, single edge, single vertex, or an external remote point and only the body-to-ground connection type is allowed. Similar to a spring, there is a Mobile side and Reference side for the bearing connection. The Reference side is assumed to be grounded (or fixed) and the mobile side is set to the scoped entity. Unlike springs, the location of the reference side is set to that of the mobile side because they can be coincident during a linear analysis. For more information about the use of a spring-damper bearing, see COMBI214 - 2D Spring-Damper Bearing in the Mechanical APDL Theory Reference.

Apply Bearing To add a Bearing: 1. Add a Connections folder if one is not already in the tree, by highlighting the Model object and choosing Connections from the Model Context Toolbar (p. 55) or by choosing Insert>Connections from the context menu (right-click). 2. Add a Bearing object by highlighting the Connections folder, opening the Body-Ground drop-down list and then selecting Bearing or by right-clicking on the Connections folder and selecting Insert>Bearing from the context menu. 3. Set the following in the Details view: a. Under the Reference category, specify the Rotation Plane property for your model. Selections include: 632

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Bearings • None (default) • X-Y Plane • Y-Z Plane • X-Z Plane b. Scoping Method as Geometry Selection (default) or Named Selection. The Scoping Method may also be specified to a user-defined Remote Point, if available. c. Connection Behavior as either Rigid (default) or Deformable. If the Bearing is scoped to a Remote Point, the Bearing assumes the Behavior of the Remote Point. The Behavior formulation Coupled is not supported for Bearings. d. Pinball Region as desired. Use the Pinball Region to define where the bearing attaches to face(s), edge(s), or a single vertex if the default location is not desirable. By default, the entire face/edge/vertex is tied to the bearing element. In the event that this is not desirable, you can choose to enter a Pinball Region value. For example, your topology could have a large number of nodes leading to solution processing inefficiencies. Or, if there is overlap between the bearings’s scoped faces and another displacement boundary condition can lead to over-constraint and consequently solver failures.

Note • The Pinball Region and Behavior settings are applicable to underlying bodies that are flexible. • The Pinball Region and Behavior settings are not applicable to a Bearing scoped to the vertex of line body. • A Bearing is classified as a remote boundary condition. Refer to the Remote Boundary Conditions section for a listing of all remote boundary conditions and their characteristics.

The following example illustrates a Bearing on a cylindrical face with customized Details settings.

The stiffness characteristics K11, K22, K12, and K21, and damping characteristics C11, C22, C12, and C21 are used to model four spring-damper sets in a plane of a rotating shaft in this example. For more inRelease 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Setting Connections formation about the spring-damper orientation, see COMBI214 - 2D Spring-Damper Bearing in the Mechanical APDL Theory Reference. The bearing is created on a face of the shaft that is perpendicular to the Z-axis. As the Z-axis is the rotating axis of the shaft, the X-Y Plane is selected for the Rotation Plane option. While the bearing in this example is defined using Global Coordinate System, it can also be defined with a user-defined local coordinate system. When changing from one coordinate system to another, the Bearing needs the scoping to be updated to desired location for the new coordinate system. Note that the coordinates for the Mobile side cannot be modified. The location is read-only. For a bearing to be modeled properly, the location of the mobile side must lie on the rotating axis of the shaft.

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Configuring Analysis Settings The following topics are covered in this section. Analysis Settings for Most Analysis Types Steps and Step Controls for Static and Transient Analyses Analysis Settings for Explicit Dynamics Analyses

Analysis Settings for Most Analysis Types When you define an analysis type, an Analysis Settings object is automatically inserted in the Mechanical application tree. With this object selected, you can define various solution options in the Details view that are customized to the specific analysis type, such as enabling large deflection for a stress analysis. The available control groups as well as the control settings within each group vary depending on the analysis type you have chosen. The sections that follow outline the availability of the control settings for each of these groups and describe the controls available in each group. Step Controls Solver Controls Restart Analysis Restart Controls Creep Controls Cyclic Controls Radiosity Controls Options for Analyses Damping Controls Nonlinear Controls Output Controls Analysis Data Management Rotordynamics Controls Visibility Explicit Dynamics settings are examined in a separate section.

Step Controls Step Controls play an important role in static and transient dynamic analyses. Step controls are used to perform two distinct functions: 1. Define Steps. 2. Specify the Analysis Settings for each step.

Defining Steps See the procedure, Specifying Analysis Settings for Multiple Steps located in the Establish Analysis Settings (p. 134) section. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Configuring Analysis Settings

Specifying Analysis Settings for Each Step The following items can be changed on a per step basis: • Step Controls • Nonlinear Controls • Output Controls

Step Controls The selections available in the Details view for Step Controls group are described below. • Current Step Number: shows the step ID for which the settings in Step Controls, Nonlinear Controls, and Output Controls are applicable. The currently selected step is also highlighted in the bar at the bottom of the Graph window. You can select multiple steps by selecting rows in the data grid or the bars at the bottom of the Graph window. In this case the Current Step Number will be set to multi-step. In this case any settings modified will affect all selected steps.

• Step End Time: shows the end time of the current step number. When multiple steps are selected this will indicate multi-step. • Auto Time Stepping: is discussed in detail in the Automatic Time Stepping (p. 668) section. Automatic time stepping is available for static and transient analyses, and is especially useful for nonlinear solutions. Settings for controlling automatic time stepping are included in a drop down menu under Auto Time Stepping in the Details view. The following options are available: – Program Controlled (default setting): the Mechanical application automatically switches time stepping on and off as needed. A check is performed on non-convergent patterns. The physics of the simulation is also taken into account. The Program Controlled settings are presented in the following table: Auto Time Stepping Program Controlled Settings Analysis Type

Initial Substeps

Minimum Substeps

Maximum Substeps

Linear Static Structural

1

1

1

Nonlinear Static Structural

1

1

10

Linear Steady-State Thermal

1

1

10

Nonlinear Steady-State Thermal

1

1

10

100

10

1000

Transient Thermal

– On: You control time stepping by completing the following fields that only appear if you choose this option. No checks are performed on non-convergent patterns and the physics of the simulation is not taken into account.

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Analysis Settings for Most Analysis Types → Initial Substeps: specifies the size of the first substep. The default is 1. → Minimum Substeps: specifies the minimum number of substeps to be taken (that is, the maximum time step size). The default is 1. → Maximum Substeps: specifies the maximum number of substeps to be taken (that is, the minimum time step size). The default is 10. – Off: no time stepping is enabled. You are prompted to enter the Number Of Substeps. The default is 1. • Define By allows you to set the limits on load increment in one of two ways. You can specify the Initial, Minimum and Maximum number of substeps for a step or equivalently specify the Initial, Minimum and Maximum time step size. • Carry Over Time Step is an option available when you have multiple steps. This is useful when you do not want any abrupt changes in the load increments between steps. When this is set the Initial time step size of a step will be equal to the last time step size of the previous step. • Time Integration is valid only for a Transient Structural or Transient Thermal analysis. This field indicates whether a step should include transient effects (for example, structural inertia, thermal capacitance) or whether it is a static (steady-state) step. This field can be used to set up the Initial Conditions for a transient analysis. – On: default for Transient analyses. – Off: do not include structural inertia or thermal capacitance in solving this step.

Note With Time Integration set to Off in Transient Structural analyses, Workbench does not compute velocity results. Therefore spring damping forces, which are derived from velocity will equal zero. This is not the case for Rigid Dynamics analyses.

Activation/Deactivation of Loads You can activate (include) or deactivate (delete) a load from being used in the analysis within the time span of a step. For most loads (for example, pressure or force) deleting the load is the same as setting the load value to zero. But for certain loads such as specified displacement this is not the case. Activation and deactivation of loads is not available to the Samcef solver.

Note Changing the method of how a multiple-step load value is specified (such as Tabular to Constant), the Activation/Deactivation state of all steps resets to the default, Active. To activate or deactivate a load in a stepped analysis: 1.

Highlight the load within a step in the Graph or a specific step in the Tabular Data window.

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Configuring Analysis Settings 2.

Click the right mouse button and choose Activate/Deactivate at this step!.

Note For displacements and remote displacements, it is possible to deactivate only one degree of freedom within a step. For Temperature, Thermal Condition, Heat Generation, Voltage, and Current loads, the following rules apply when multiple load objects of the same type exist on common geometry selections: • A load can assume any one of the following states during each load step: – Active: Load is active during the first step. – Reactivated: Load is active during the current step, but was deactivated during the previous step. A change in step status exists. – Deactivated: Load is deactivated at the current step, but was active during the previous step. A change in step status exists. – Unchanged: No change in step status exists. • During the first step, an active load will overwrite other active loads that exist higher (previously added) in the tree. • During any other subsequent step, commands are sent to the solver only if a change in step status exists for a load. Hence, any unchanged loads will get overwritten by other reactivated or deactivated loads irrespective of their location in the tree. A reactivated/deactivated load will overwrite other reactivated and deactivated loads that exist higher (previously added) in the tree.

Note For each load step, if both Imported Loads and user-specified loads are applied on common geometry selections, the Imported Loads take precedence. See respective Imported Load for more details. For Imported loads commands are sent to the solver at a load step if the Imported Load: • Is active and has data specified for the current step • Has been reactivated and has data for the current step or at a previous step • Has been deactivated and data was applied at the previous step.

Note For imported loads specified as tables, the data is available outside the range of specified analysis times/frequencies. If the solve time/frequency for a step/sub-step falls outside the specified Analysis Time/Frequency, then the load value at the nearest specified analysis time is used.

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Analysis Settings for Most Analysis Types The tabular data view provides the equation for the calculation of values through piecewise linear interpolation at steps where data is not specified.

Some scenarios where load deactivation is useful are: • Springback of a cantilever beam after a plasticity analysis (see example below). • Bolt pretension sequence (Deactivation is possible by setting Define By to Open for the load step of interest). • Specifying different initial velocities for different parts in a transient analysis. Example: Springback of a cantilever beam after a plasticity analysis In this case a Y displacement of -2.00 inch is applied in the first Step. In the second step this load is deactivated (deleted). Deactivated portions of a load are shown in gray in the Graph and also have a red stop bars indicating the deactivation. The corresponding cells in the data grid are also shown in gray.

In this example the second step has a displacement value of -1.5. However since the load is deactivated this will not have any effect until the third step. In the third step a displacement of -1.5 will be step applied from the sprung-back location.

Solver Controls The properties provided by the Solver Controls category vary based on the specified Analysis Type. This table denotes which Details view properties are supported for each analysis type. The remainder of the section describes the functions and features of the properties.

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Configuring Analysis Settings Analysis Type Static Structural

Details View Properties

RiTrangid sient ModDyStrucal namtural ics

Lin- Steady MagTranear netosient Buck- State statThermal ling Thermal ic

Electric

Thermal Electric

Damped Solver Type Mode Reuse Store Complex Solution Weak Springs Large Deflection Inertia Relief Time Integration and Constraint Stabilization Fracture

Damped - Modal Analyses Only The Damped property is only available for Modal analyses. Set this control to Yes to enable a damped modal system where the natural frequencies and mode shapes become complex. The default setting is No.

Solver Type For Static Structural and Transient Structural analysis types, by default, the Solver Type property is set to Program Controlled, which lets the program select the optimal solver. However you can manually select the Direct or Iterative solver. The Direct option uses the Sparse solver and the Iterative option uses the PCG or ICCG (for Electric and Electromagnetic analyses) solver. See the Help for the EQSLV command in the Mechanical APDL Command Reference for more information about solver selection. For a Modal Analysis, additional Solver Type options are available and include: • Unsymmetric • Supernode • Subspace The Direct, Iterative, Unsymmetric, Supernode, and Subspace types are used to solve a modal system that does not include any damping effects – the Damped property is set to No. By default, the Solver Type property is set to Program Controlled for a Modal Analysis. Except for the Unsymmetric option, the solver types are intended to solve Eigen solutions with symmetric mass and stiffness. For a large model, the Iterative solver is preferred over the Direct solver for its efficiency in terms of solution time and memory usage. During a Modal analysis, the Direct solver uses the Block Lanczos extraction method that employs an automated shift strategy, combined with a Sturm sequence check, to extract the number of eigenvalues requested. The Sturm sequence check ensures that the requested number of eigen frequencies beyond the user supplied shift frequency (FREQB on the MODOPT command) is found without missing any

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Analysis Settings for Most Analysis Types modes. Please see the Block Lanczos help in the Eigenvalue and Eigenvector Extraction section of the Mechanical APDL Theory Reference. The Supernode solver is recommended for extracting a large number of modes. Selecting Supernode as the Solver Type automatically sets the Limit Search to Range property to Yes in the Options category. This selection also displays the Range Minimum and Range Maximum properties and requires a Range Maximum frequency entry. Alternatively, you may reset the Limit Search to Range property to No to find all of the possible modes without any restrictions on the frequency range. Unlike the Direct solver, the Subspace solver doesn't perform Sturm sequence check by default (STRMCK is OFF by default in SUBOPT command), making it relatively faster than Direct solver and also has reasonable accuracy. In addition, the Subspace solver supports DANSYS allowing you to take advantage of a distributed architecture to perform faster computations. For a Linear Buckling Analysis, the Solver Type options include: Program Controlled, Direct, and Subspace. By default, the Program Controlled option uses the Direct solver. Refer to the BUCOPT command for additional information. For the modal systems with unsymmetric mass and/or stiffness, the Unsymmetric solver is required for solving the Eigen solutions. See the Help for the MODOPT command in the Mechanical APDL Command Reference for more information about solver selection. However, if the Damped property is set to Yes, the Solver Type options include: • Program Controlled • Full Damped • Reduced Damped The default option is Program Controlled. The Reduced Damped solver is preferred over the Full Damped solver for its efficiency in terms of solution time. However, the Reduced Damped solver is not recommended when high damping effects are present because it can become inaccurate.

Mode Reuse - Modal Analyses Only The Mode Reuse property is only available for Modal analyses when you specify the Solver Type as Reduced Damped. This property allows the solver to compute complex eigensolutions efficiently during subsequent solve points by reusing the undamped eigensolution that is calculated at the first solve point. The default setting is Program Controlled. Set this property to Yes to enable it or No to disable the property.

Store Complex Solution - Modal Analyses Only This property is only available for a Modal Analysis and only when the Damped property is set to Yes and the Solver Type is set to Reduced Damped. It allows you to solve and store a damped modal system as an undamped modal system.

Weak Springs For stress or shape simulations, the addition of weak springs can facilitate a solution by preventing numerical instability, while not having an effect on real world engineering loads. The following Weak Springs settings are available in the Details view:

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Configuring Analysis Settings • Program Controlled (default setting): Workbench determines if weak springs will facilitate the solution, then adds a standard weak springs stiffness value accordingly. • On: Workbench always adds a weak spring stiffness. Choosing On causes a Spring Stiffness option to appear that allows you to control the amount of weak spring stiffness. Your choices are to use the standard stiffness mentioned above for the Program Controlled setting of Weak Springs or to enter a customized value. The following situations may prompt you to choose a customized stiffness value: a. The standard weak spring stiffness value may produce springs that are too weak such that the solution does not occur, or that too much rigid body motion occurs. b. You may judge that the standard weak spring stiffness value is too high (rare case). c. You many want to vary the weak spring stiffness value to determine the impact on the simulation. The following Spring Stiffness settings are available: – Program Controlled (default setting): Adds a standard weak spring stiffness (same as the value added for the Program Controlled setting of Weak Springs). – Factor: Adds a customized weak spring stiffness whose value equals the Program Controlled standard value times the value you enter in the Spring Stiffness Factor field (appears only if you choose Factor). For example, setting Spring Stiffness Factor equal to 20 means that the weak springs will be 20 times stronger than the Program Controlled standard value. – Manual: Adds a customized weak spring stiffness whose value you enter (in units of force/length) in the Spring Stiffness Value field (appears only if you choose Manual). • Off: Weak springs are not added. Use this setting if you are confident that weak springs are not necessary for a solution.

Large Deflection This field, applicable to static structural and Transient Structural analyses, determines whether the solver should take into account large deformation effects such as large deflection, large rotation, and large strain. Set Large Deflection to On if you expect large deflections (as in the case of a long, slender bar under bending) or large strains (as in a metal-forming problem). When using hyperelastic material models, you must set Large Deflection On.

Inertia Relief - Linear Static Structural Analyses Only Calculates accelerations to counterbalance the applied loads. Displacement constraints on the structure should only be those necessary to prevent rigid-body motions (6 for a 3D structure). The sum of the reaction forces at the constraint points will be zero. Accelerations are calculated from the element mass matrices and the applied forces. Data needed to calculate the mass (such as density) must be input. Both translational and rotational accelerations may be calculated. This option applies only to the linear static structural analyses. Nonlinearities, elements that operate in the nodal coordinate system, and axisymmetric or generalized plane strain elements are not allowed. Models with both 2D and 3D element types or with symmetry boundary constraints are not recommended. Loads may be input as usual. Displacements and stresses are calculated as usual. Symmetry models are not valid for inertia relief analysis.

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Analysis Settings for Most Analysis Types

Time Integration Type - Transient Analysis of Multiple Rigid Bodies Only This feature is applicable to a Rigid Dynamics analysis. The Time Integration Type feature employs the fourth and fifth order polynomial approximation of the Runge-Kutta algorithm to enable the Mechanical application to integrate the equations of motion during analyses. This feature allows you to choose time integration algorithms and specify whether to use constraint stabilization. The fifth order approximation usually allows for larger time steps and can therefore reduce the total simulation time. The Details view Solver Controls options for the Time Integration Type include: • Time Integration Type field. Available time integration algorithms include: – Runge-Kutta 4 (default setting) - Fourth Order Runge-Kutta – Runge-Kutta 5 - Fifth Order Runge-Kutta • Use Stabilization field. When specified, this option provides the numerical equivalent for spring and damping effects and is proportional to the constraint violation and its time derivative. If there is no constraint violation, the spring and damping has no effect. The addition of artificial spring and damping does not change the dynamic properties of the model. Stabilization options include: – Off - (default setting) - constraint stabilization is ignored. – On - Because constraint stabilization has a minimal impact on calculation time, its use is recommended. When specified, the Stabilization Parameters field also displays. Stabilization Parameters options include: – Program Controlled - valid for most applications. – User Defined - manual entry of spring stiffness (Alpha) and damping ratio (Beta) required.

Note Based on your application, it may be necessary to enter customized settings for Alpha and Beta. In this case, start with small values and use the same value in both fields. Alpha and Beta values that are too small have little effect and values that are too large cause the time step to be too small. The valid values for Alpha and Beta are Alpha > = 0 and Beta > = 0. If Both Alpha and Beta are zero, the stabilization will have no effect.

Fracture For fracture analyses, only one control exists. The Fracture property, which ensures that the effect of cracks are included in the solution, only applies to static structural analysis. It is visible only if the Fracture folder exists in the model. The default setting is On.

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Configuring Analysis Settings

Restart Analysis Note This group is displayed in the Details view only if restart points are available. Restart points can be generated by adjusting the settings in the Restart Controls group. You will also need to set Delete Unneeded Files, under the Analysis Data Management group to No so that restart point files are retained after a solve. The Restart Analysis group is available for the following analysis types: • Static Structural • Transient Structural These control whether to use restart points in subsequent solution restarts. If restart points should be used, Load Step, Substep and Time help reveal the point's identity in the calculation sequence.

Note When using a modal system database from a version prior to the most current version of Mechanical, it is possible to encounter incompatibility of the file.esav, created by a linked static structural system. This incompatibility can cause the modal system’s solution to fail. In the event you experience this issue, use the Clear Generated Data feature and resolve the static structural system. The Restart Analysis controls are as follows: • Restart Type: By default, Mechanical tracks the state of restart points and selects the most appropriate point when set to Program Controlled. You may choose different restart points by setting this to Manual, however. To disable solution restarts altogether, set it to Off. • Current Restart Point: This option lets you choose which restart point to use. This option is displayed only if Restart Type set to Manual. • Load Step: Displays the Load Step of the restart point to use. If no restart points are available (or all are invalid for a Restart Type of Program Controlled) the display is Initial. • Substep: Displays the Substep of the restart point to use. If no restart points are available (or all are invalid for a Restart Type of Program Controlled) the display is Initial. • Time: Displays the time of the restart point to use.

Restart Controls These control the creation of Restart Points. Because each Restart Point consists of special files written by the solver, restart controls can help you manage the compromise between flexibility in conducting your analyses and disk space usage. Please see the Solution Restarts section for more information about the restart capability and how it relates to Restart Points. The Restart Controls are as follows: • Generate Restart Points: Enables the creation of restart points. 644

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Analysis Settings for Most Analysis Types – Program Controlled: Instructs the program to select restart point generation settings for you. The setting is equivalent to Load Step = Last and Substep = Last. – Manual: Allows you access to the detailed settings for restart point generation. – Off: Restricts any new restart points from being created. • Load Step: Specifies what load steps are to create restart points. Set to All to obtain restart points in all load steps, or to Last to obtain a restart point in the last load step only. • Substep: Specifies how often the restart points are created within a load step. Set to one of the following: – Last to write the files for the last substep of the load step only. – All to write the files for all substeps of the load step. – Specified Recurrence Rate and enter a number N, in the Value field, to generate restart points for a specified number of substeps per load step. – Equally Spaced Points and enter a number N, in the Value field, to generate restart points at equally spaced time intervals within a load step. • Maximum Points to Save Per Step: Specifies the maximum number of files to save for the load step. Choose one of the following options: – Enter 0 to not overwrite any existing files. The maximum number of files for one run is 999. If this number is reached before the analysis is complete, the analysis will continue but will no longer write any files. After 0 is entered, the field will show All. – Enter a positive number to specify the maximum number of files to keep for each load step. When the maximum number has been written for each load step, the first file of that load step will be overwritten for subsequent substeps.

Note If you want to interrupt the solution in a linear transient analysis, by default, the interrupt will be at load step boundaries only (as opposed to nonlinear analyses where interrupts occur at substeps). However, if you want to interrupt a solution to a linear transient analysis on a substep basis, set the following: Generate Restart Controls = Manual, Load Step = All, Substep = All, and Maximum Points to Save Per Step = 1. These settings allow you to accomplish the interrupt on a substep basis without filling up your disk with restart files.

• Retain Files After Full Solve: When restart points are requested, the necessary restart files are always retained for an incomplete solve due to a convergence failure or user request. However, when the solve completes successfully, you have the option to request to either keep the restart points by setting this field to Yes, or to delete them by setting this field to No. You can control this setting here in the Details

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Configuring Analysis Settings view of the Analysis Settings object, or under Tools> Options in the Analysis Settings and Solution preferences list. The setting in the Details view overrides the preference setting.

Note Retain Files After Full Solve has interactions with other controls. Under the Analysis Data Management (p. 664) category, setting Future Analysis to Prestressed forces the restart files to be retained. Similarly, setting Delete Unneeded Files to No implies that restart files are to be retained.

Creep Controls Creep is a rate-dependent material nonlinearity in which the material continues to deform under a constant load. You can perform an implicit creep analysis for a static or transient structural analysis. Creep Controls are available in the Details view of the analysis settings for these two environments only after you have selected a creep material for at least one prototype in the analysis. The Creep Controls group is available for the following analysis types: • Static Structural • Transient Structural Creep controls are step-aware, meaning that you are allowed to set different creep controls for different load steps in a multistep analysis. If there were multiple load steps in the analysis before you chose the creep material, then choosing the creep material will set the Creep Controls properties to their default value. The Creep Controls group includes the following properties: • Creep Behavior - The default value is Off for the first load step and On for all the subsequent load steps. You may change it according to your analysis. • Creep Limit Ratio (available only if Creep Behavior is set to On) - This property issues the Mechanical APDL CUTCONTROL command with your input value of creep limit ratio. (Refer to the CUTCONTROL command description for details). The default value of Creep Limit Ratio is 1. You are allowed to pick any non-negative value.

Cyclic Controls The Harmonic Index Range setting within the Cyclic Controls category is only used in a Modal analysis that involves cyclic symmetry to specify the solution ranges for the harmonic index. The setting appears if you have defined a Cyclic Region for this analysis. • The Program Controlled option solves all applicable harmonic indices.

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Analysis Settings for Most Analysis Types • The Manual option exposes additional fields that allow you to specify a range of harmonic indices for solution from the Minimum value to the Maximum value in steps of the Interval value.

Note Static Structural cyclic symmetry solutions always use all harmonic indices required for the applied loads.

Radiosity Controls The Radiosity Controls group is available for the following analysis types: • Steady - State Thermal • Transient Thermal • Thermal Electric The following settings within the Radiosity Controls category are used in conjunction with the Radiation boundary condition when defining surface-to-surface radiation for thermal related analyses that use the ANSYS solver. These settings are based on the RADOPT command in Mechanical APDL. • Radiosity Solver • Flux Convergence • Maximum Iteration • Solver Tolerance (dependent upon the unit of measure) • Over Relaxation For the Radiosity Solver property, selections include the Gauss-Seidel iterative solver (Program Controlled default), the Direct solver, or the Iterative Jacobi solver.

View Factors for 3D Geometry For 3D geometry, the Hemicube Resolution setting is also available based on the HEMIOPT command in Mechanical APDL. See the View Factor Calculation (3-D): Hemicube Method section in the Mechanical APDL Theory Reference for further information.

View Factors for 2-D Geometry For 2–D geometry, the following settings are available and are based on the V2DOPT command in Mechanical APDL: • View Factor Method • Number of Zones • Axisymmetric Divisions See the following sections of the Mechanical APDL help for further information on these settings:

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Configuring Analysis Settings • Using the Radiosity Solver Method in the Thermal Analysis Guide. • Mechanical APDL Theory Reference sections: – Non-Hidden Method – Hidden Method – View Factors of Axisymmetric Bodies

Options for Analyses An Options control group is included in the Analysis Settings Details view for the following analysis types only: • Modal • Harmonic • Transient Structural • Linear Buckling • Random Vibration • Response Spectrum

Modal Analysis Options Group For Modal analyses, the Options group includes the following controls: Max Modes to Find Specifies the number of natural frequencies to solve for in a modal analysis. Limit Search Range Allows you to specify a frequency range within which to find the natural frequencies. The default is set to No. If you set this to Yes, you can enter a minimum and maximum frequency value. If you specify a range the solver will strive to extract as many frequencies as possible within the specified range subject to a maximum specified in the Max Modes to Find field.

Harmonic Analysis Options Group The Options group controls for Harmonic analyses are described below. Frequency Sweep Range This is set by defining the Range Minimum and Range Maximum values under Options in the Details view. Solution Intervals This sets the number of the solution points between the Frequency Sweep Range. You can request any number of harmonic solutions to be calculated. The solutions are evenly spaced within the specified frequency range, as long as clustering is not active. For example, if you specify 10 solutions in the range 30 to 40 Hz, the program will calculate the response at 31, 32, 33, ..., 39, and 40 Hz. No response is calculated at the lower end of the frequency range.

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Analysis Settings for Most Analysis Types Solution Method Three solution methods are available to perform harmonic analysis: Mode Superposition method, Direct Integration (Full) method, and the Variational Technology method.

Mode Superposition Method Mode Superposition is the default method, and generally provides results faster than the Full method. In the Mode Superposition method a modal analysis is first performed to compute the natural frequencies and mode shapes. Then the mode superposition solution is carried out where these mode shapes are combined to arrive at a solution.

Modal Frequency Range Specifies the range of frequencies over which mode shapes will be computed in the modal analysis: • Program Controlled: The modal sweep range is automatically set to 200% of the upper harmonic limit and 50% of the lower harmonic limit. This setting is adequate for most simulations.

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Configuring Analysis Settings • Manual: Allows you to manually set the modal sweep range. Choosing Manual displays the Modal Range Minimum and Modal Range Maximum fields where you can specify these values. Include Residual Vector This property is available for a Harmonic Analysis Using Linked Modal Analysis System. It can be turned On to execute the RESVEC command and calculate or include residual vectors. The default setting is Off. Please see the RESVEC command in the Mechanical APDL Command Reference for additional information. Cluster Results and Cluster Number (Mode Superposition only) This option allows the solver to automatically cluster solution points near the structure’s natural frequencies ensuring capture of behavior near the peak responses. This results in a smoother, more accurate response curves. Cluster Number specifies the number of solutions on each side of a natural frequency. The default is to calculate four solutions, but you may specify any number from 2 to 20. Options: • Solution Method = Mode Superposition • Cluster Number = Yes Solution Intervals = 15: Here 15 solutions are evenly spaced within the frequency range. Note how the peak can be missed altogether.

Cluster = 5: Here 5 solutions are performed automatically on either side of each natural frequency capturing the behavior near the peaks.

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Analysis Settings for Most Analysis Types

Store Results At All Frequencies Upon solution, harmonic environments store data specified in the Output Controls for all intervals in the frequency range. Consequently, seeking additional results at new frequencies will no longer force a solved harmonic environment to be resolved. This choice will lead to a better compromise between storage space (results are now stored in binary form in the RST file) and speed (by reducing the need to resort to the solver to supply new results). If storage is an issue, set the Store Results At All Frequencies to No. The application retains minimal data with this setting, providing only the harmonic results requested at the time of solution. As a result, the Output Controls do not control the availability of the results. This option is especially useful for Mode Superposition harmonic response analyses with frequency clustering. It is unavailable for harmonic analyses solved with the Full method.

Note With this option set to No, the addition of new frequency or phase responses to a solved environment requires a new solution. Adding a new contour result of any type (stress or strain) or a new probe result of any type (reaction force, reaction moment, or bearing) for the first time on a solved environment requires you to solve, but adding additional contour results or probe results of the same type does not share this requirement; data from the closest available frequency is displayed (the reported frequency is noted on each result). Note that the values of frequency, type of contour results (displacement, stress, or strain) and type of probe results (reaction force, reaction moment, or bearing) at the moment of the solution determine the contents of the result file and the subsequent availability of data. Planning these choices can significantly reduce the need to resolve an analysis. Full Method (Direct Integration) The Full method uses the full system matrices for the solution calculations. It is more thorough but also requires greater processing time and capability.

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Configuring Analysis Settings

The property Variational Technology displays when Full is specified. This option is an alternate Solution Method that is based on the harmonic sweep algorithm of the Full method. The options include: • Program Controlled (default setting) - the application selects the most efficient method (Full or Variational Technology). • Yes - Specifies that the Variational Technology method is used. • No - Specifies that the Full method is used. For additional information, see Harmonic Analysis Variational Technology Method, and Variational Technology, as well as the HROPT command in the Command Reference.

Transient Structural Options Group Include Residual Vector Include Residual Vector is the only Options group property for a Transient Structural Analysis Using Linked Modal Analysis System. It can be turned On to execute the RESVEC command and calculate or include residual vectors. The default setting is Off. Please see the RESVEC command in the Mechanical APDL Command Reference for additional information.

Linear Buckling Options Group For Linear Buckling analyses, the Options group contains the Max Modes to Find control. You need to specify the number of buckling load factors and corresponding buckling mode shapes of interest. Typically only the first (lowest) buckling load factor is of interest.

Random Vibration Options Group For Random Vibration analyses, the Options group includes the following controls. Number of Modes to Use Specifies the number of modes to use from the modal analysis. A conservative rule of thumb is to include modes that cover 1.5 times the maximum frequency in the PSD excitation table.

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Analysis Settings for Most Analysis Types Exclude Insignificant Modes When set to Yes, allows you to not include modes for the mode combination as determined by the threshold value you set in the Mode Significant Level field. The default value of 0 means all modes are selected (same as setting Exclude Insignificant Modes to No) while a value of 1 means that no modes are selected. The higher the threshold is set, the fewer modes are selected for mode combination.

Response Spectrum Options Group For Response Spectrum analyses, the Options group includes the following controls. Number of Modes to Use Specify the number of modes to use from the modal analysis. It is suggested to have modes that span 1.5 times the maximum frequency defined in input excitation spectrum. Spectrum Type Specify either Single Point or Multiple Points. If two or more input excitation spectrums are defined on the same fixed degree of freedoms, use Single Point, otherwise use Multiple Points. Modes Combination Type Specify a method to be used for response spectrum calculation. Choices are SRSS, CQC, and ROSE. In general, the SRSS method is more conservative than the other methods. The SRSS method assumes that all maximum modal values are uncorrelated. For a complex structural component in three dimensions, it is not uncommon to have modes that are coupled. In this case, the assumption overestimates the responses overall. On the other hand, the CQC and the ROSE methods accommodate the deficiency of the SRSS by providing a means of evaluating modal correlation for the response spectrum analysis. Mathematically, the approach is built upon random vibration theory assuming a finite duration of white noise excitation. The ability to account for the modes coupling makes the response estimate from the CQC and ROSE methods more realistic and closer to the exact time history solution.

Damping Controls The controls of the Damping Controls group vary based on the type of analysis being performed. Supported analysis types include: • Transient Structural • Harmonic • Random Vibration/Response Spectrum The following forms of damping are available in the application: • Constant Damping. This property is available for Random Vibration analyses. The default setting is Program Controlled. You may also set the property to Manual. • Constant Damping Ratio. This specifies the amount of damping in the structure as a percentage of critical damping. If you set this in conjunction with the Stiffness Coefficient, and Mass Coefficient, the effects are cumulative. You define the Constant Damping Ratio in the Details view of the Analysis Settings object. The Constant Damping Ratio can also be specified in Engineering Data. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Configuring Analysis Settings For a Random Vibration analysis, this property defaults to 0.01 (1%). Set the Constant Damping property to Manual to specify the value. • Stiffness Coefficient Defined By. Define the Stiffness Coefficient by entering a value, Direct, or by entering a Frequency and a Damping Ratio, Damping vs. Frequency. • Stiffness Coefficient (Beta Damping, β). A coefficient value that is used to define a Beta damping by multiplying it with stiffness. You can enter the value directly or the value can be computed from a damping ratio at a specified frequency. You define a Stiffness Coefficient in the Details view of the Analysis Settings object. The Beta Damping can also be specified in Engineering Data. Refer to the BETAD command in the Mechanical APDL Command Reference for more information about the Beta Damping Factor. • Frequency. Visible when Stiffness Coefficient Defined By is set to Damping vs. Frequency. • Damping Ratio. Visible when Stiffness Coefficient Defined By is set to Damping vs. Frequency. The value of β is not generally known directly, but is calculated from the modal damping ratio, ξi. ξi is the ratio of actual damping to critical damping for a particular mode of vibration, i. If ωi is the natural circular frequency, then the beta damping is related to the damping ratio as β = 2 ξi/ωi . Only one value of β can be input in a step, so choose the most dominant frequency active in that step to calculate β. • Mass Coefficient (Alpha Damping Factor, α). A coefficient that is used to define an Alpha damping by multiplying it with mass. Beta and Alpha damping factors are collectively called Rayleigh damping. The Alpha Damping can also be specified in Engineering Data. Refer to the ALPHAD command in the Mechanical APDL Command Reference for more information about the Alpha Damping Factor. • Numerical Damping. Also referred to as amplitude decay factor (γ), this option controls the numerical noise produced by the higher frequencies of a structure. Usually the contributions of these high frequency modes are not accurate and some numerical damping is preferable. A default value of 0.1 is used for Transient Structural analysis and a default value of 0.005 is used for Transient Structural analysis using a linked Modal analysis system. To change the default, change the Numerical Damping field in the Details view of the Analysis Settings object to Manual from Program Controlled, which allows you to enter a custom value in the Numerical Damping Value field. • Material Damping: there are two types of material-based damping, Material Dependent Damping and Constant Damping Coefficient. Material Dependent Damping consists of beta damping and alpha damping. These are defined as material properties in Engineering Data. • Element Damping: Spring damping and Bearing damping are defined in the Details view of the Spring object and Bearing object. You can specify more than one form of damping in a model. In addition to structural damping and material damping, the model can have damping from spring and bearing connection, namely Element

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Analysis Settings for Most Analysis Types Damping (see above). The application formulates the damping matrix as the sum of all the specified forms of damping.

Note Restrictions of applying damping in each analysis type can be found in Damping section of the MADPL Structural Analysis Guide.

Nonlinear Controls This section describes the properties provided by Nonlinear Controls category. The properties of this category vary based on analysis type. The subsections listed here describe the Nonlinear Controls properties for each supported analysis type. • Nonlinear Controls for Steady-State, Static, and Transient Structural Analyses • Nonlinear Controls for Transient Thermal Analyses • Nonlinear Controls for Rigid Dynamics Analyses

Nonlinear Controls for Steady-State, Static, and Transient Analyses This topic examines the Nonlinear Controls as they apply to Steady-State, Static, and Transient Structural Analyses, which include Electric, Magnetostatic, Static Structural, Transient Structural, Steady-State Thermal, and Thermal-Electric analyses. Newton-Raphson Option For nonlinear Static Structural and Full Transient Structural analysis types, the Newton-Raphson Option property is available. This property allows you to specify how often the stiffness matrix is updated during the solution process. Newton-Raphson Option property options include: • Program Controlled (default setting) • Full • Modified • Unsymmetric The Program Controlled option allows the program to select the Newton-Raphson Option setting based on the nonlinearities present in your model. For more information about the additional options, see the Newton-Raphson Option section in the Mechanical APDL Structural Analysis Guide. If you experience convergence difficulties, switching to an Unsymmetric solver may aid in Convergence. Convergence Criterion When solving nonlinear steady-state, static, or transient analyses, an iterative procedure (equilibrium iterations) is carried out at each substep. Successful solution is indicated when the out-of-balance loads are less than the specified convergence criteria. Criteria appropriate for the analysis type and physics are displayed in this grouping. Convergence controls are “step aware”. This means that the setting can be different for each step. The following convergence criteria properties are available: Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Configuring Analysis Settings • Electric analysis: Voltage Convergence and Current Convergence. • Magnetostatic analysis: CSG Convergence and AMP Convergence. • Static Structural analysis and Transient Structural analysis: Force Convergence, Moment Convergence, Displacement Convergence, and Rotation Convergence. • Steady-State Thermal analysis: Heat Convergence and Temperature Convergence. • Thermal-Electric analysis: Heat Convergence, Temperature Convergence, Voltage Convergence, and Current Convergence. The following convergence controls are available for each of these properties: • Program Controlled (default setting): The application sets the convergence criteria. • On: You specify that a convergence criterion is activated. Once activated, additional properties become available and include: – Value: This is the reference value that the solver uses to establish convergence. The recommended and program controlled setting, Calculated by solver, automatically calculates the value based on external forces, including reactions, or you can input a constant value. When Temperature Convergence is set to On, the Value field provides a drop-down menu with the options Calculated by solver or User Input. Selecting User Input displays an Input Value field you use to enter a value. When any other convergence property is set to On, selecting the Calculated by solver field allows you to manually enter a value. – When any other convergence is set to On, simply clicking on the Calculated by solver field allows you to add a value that replaces the Calculated by solver display. – Tolerance times Value determines the convergence criterion – Minimum Reference: This is useful for analyses where the external forces tend to zero. This can happen, for example, with free thermal expansion where rigid body motion is prevented. In these cases the larger of Value or Minimum Reference will be used as the reference value. • Remove: Indicates that an attempt will be made to remove this criterion during the solution. At least one other convergence criterion must be turned On to allow the Remove criterion to execute.

Note You may activate Displacement/Rotation convergence by the Mechanical APDL solver arbitrarily for highly nonlinear problems, even though you explicitly removed this option by choosing Remove from the drop-down menu. If for some reasons, you want to override this default behavior, it is important to turn on Force/Moment convergence and then try choosing Remove on Displacement/Rotation convergence. If you do not want any convergence options to be turned on, then you may try setting the solution controls to off, using a "Commands Objects" (p. 1141) object. Line Search

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Analysis Settings for Most Analysis Types Line search can be useful for enhancing convergence, but it can be expensive (especially with plasticity). You might consider setting Line Search on in the following cases: • When your structure is force-loaded (as opposed to displacement-controlled). • If you are analyzing a "flimsy" structure which exhibits increasing stiffness (such as a fishing pole). • If you notice (from the program output messages) oscillatory convergence patterns.

Note The Line Search control is “step aware” and can be different for each step. Stabilization Convergence difficulty due to an unstable problem is usually the result of a large displacement for small load increments. Nonlinear stabilization technique can help achieve convergence. Nonlinear stabilization can be thought of as adding artificial dampers to all of the nodes in the system. Any degree of freedom that tends to be unstable has a large displacement causing a large damping/stabilization force. This force reduces displacements at the degree of freedom so stabilization can be achieved. There are three Keys for controlling nonlinear stabilization: • Off - Deactivate stabilization (default setting). • Constant - Activate stabilization. The energy dissipation ratio or damping factor remains constant during the load step. • Reduce - Activate stabilization. The energy dissipation ratio or damping factor is reduced linearly to zero at the end of the load step from the specified or calculated value. There are two options for the Method property for stabilization control: • Energy - Use the energy dissipation ratio as the control (default setting). • Damping - Use the damping factor as the control. When Energy is specified, an Energy Dissipation Ratio needs to be entered. The energy dissipation ratio is the ratio of work done by stabilization forces to element potential energy. This value is usually a number between 0 and 1. The default value is 1.0e-4. When Damping is specified, a Damping Factor value needs to be entered. The damping factor is the value that the ANSYS solver uses to calculate stabilization forces for all subsequent substeps. This value is greater than 0.

Note The Damping Factor value is dependent on the active unit system and may influence the results if unit systems are changed. You may wish to use an initial trial value from a previous run for this entry (such as a run with the Energy Dissipation Ratio as input). See the Controlling the Stabilization Force section of the Mechanical APDL Structural Analysis Guide for additional information.

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Configuring Analysis Settings There are three options for Activation For First Substep control: • No - Stabilization is not activated for the first substep even when it does not converge after the minimal allowed time increment is reached (default setting). • On Nonconvergence - Stabilization is activated for the first substep if it still does not converge after the minimal allowed time increment is reached. Use this option for the first load step only. • Yes - Stabilization is activated for the first substep. Use this option if stabilization was active for the previous load step Key = Constant. For Stabilization Force Limit, a number between 0 and 1 should be specified. The default value is 0.2. To omit a stabilization force check, set this value to 0. Refer to Unstable Structures in the Mechanical APDL Structural Analysis Guide for assistance with using the stabilization options listed above.

Nonlinear Controls for Transient Thermal Analyses Nonlinear Formulation The Nonlinear Formulation category controls how nonlinearities are to be handled for the solution. The following options are available: • Program Controlled (default) - Mechanical automatically chooses between the Full or Quasi setting as described below. The Quasi setting is based on a default Reformulation Tolerance of 5%. The Quasi option is used by default, but the Full option is used in cases when a Radiation load is present. • Full - Manually sets formulation for a full Newton-Raphson solution. • Quasi - Manually sets formulation based on a tolerance you enter in the Reformulation Tolerance field that appears if Quasi is chosen.

Nonlinear Controls for Rigid Dynamics Analyses Relative Assembly Tolerance Allows you to specify the criterion for determining if two parts are connected. Setting the tolerance can be useful in cases where initially, parts are far enough away from one another that, by default, the program will not detect that they are connected. You could then increase the tolerance as needed. Energy Accuracy Tolerance This is the main driver to the automatic time stepping. The automatic time stepping algorithm measures the portion of potential and kinetic energy that is contained in the highest order terms of the time integration scheme, and computes the ratio of the energy to the energy variations over the previous time steps. Comparing the ratio to the Energy Accuracy Tolerance, Workbench will decide to increase or decrease the time step. See the Rigid Dynamics Analysis (p. 216) section for more information.

Output Controls The controls of the Output Controls group vary based on the type of analysis being performed. Supported analysis types include: • Static Structural 658

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Analysis Settings for Most Analysis Types • Transient Structural • Harmonic • Modal • Linear Buckling • Random Vibration/Response Spectrum • Steady - State Thermal • Transient Thermal • Electric • Thermal Electric Output Controls give you the ability to specify which type of quantities are written to the result file for use during post-processing. As a result, you can control the size of the results file which can be beneficial when performing a large analysis. The following Output Controls are available in the Details view to be activated (Yes) or not (No) and included or not included in the results file. • Stress. Writes element nodal stresses to the results file. The default value is Yes. Available for Static Structural, Transient Structural, Modal, and Linear Buckling analysis types. • Strain. Writes element elastic strains to the results file. The default value is Yes. Available for Static Structural, Transient Structural, Modal, and Linear Buckling analysis types. • Nodal Forces. Writes elemental nodal forces to the results file. Options include: – No (default setting): No nodal forces are written to the results file. – Yes: This option writes nodal forces for all nodes. It is available for Static Structural, Transient Structural, Harmonic, and Modal analysis types. This Output Control must be set to Yes if you want to use the MAPDL Command NFORCE, FSUM in Mechanical (via command snippets) because those MAPDL commands will access nodal force records in the result file as well as to obtain Reactions on the underlying source or target element. – Constrained Nodes. This option writes nodal forces for constrained nodes only. It is available for Mode Superposition (MSUP) Harmonic and Transient analyses that are linked to a Modal Analysis with the Expanded Results From option set to the Modal Analysis. This option directs Mechanical to use only the constrained nodes when calculating reaction forces and moments. The advantage is a reduced results file size. • Calculate Reactions. Turn On for Nodal Forces on constraints. Available for Modal, Harmonic, and Transient (applicable only when linked to a Modal analysis.) analysis types. • Calculate Thermal Flux. Available for Steady-State Thermal and Transient Thermal analysis types. • Keep Modal Results. Available for Random Vibration analyses only. The default value is No. This setting removes modal results from the result file in an effort to reduce file size. Setting this property to Yes allows you to perform post-processing on results of the Random Vibration solution (e.g., Response PSD) via command snippets. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Configuring Analysis Settings • Calculate Velocity. Writes Velocity to the results file. Available for Response Spectrum and Random Vibration analysis types. The default value is No for Response Spectrum and Yes for Random Vibration analysis. • Calculate Acceleration. Writes Acceleration to the results file. Available for Response Spectrum and Random Vibration analysis types. The default value is No for Response Spectrum and Yes for Random Vibration analysis. • Contact Miscellaneous. Turn On if Contact Based Force Reactions are desired. The default value is No. Available for Static and Transient Structural analysis types. Not Available when linked to a Modal analysis. • General Miscellaneous. Used to access element miscellaneous records via SMISC/NMISC expressions for user defined results. The default value is No.

Note To ensure that Membrane and Bending Stress results are not under-defined, set this option to Yes.

• Store Modal Results. Available for Modal analyses only. This field is displayed only when Stress and/or Strain are set to Yes, implying that stress and strain results are to be expanded and saved to file.mode, in addition to displacement results (mode shapes). Depending on the downstream linked analysis, you may want to save these modal stress and/or modal strain results, which are linearly superimposed to get the stress and/or strain results of the downstream linked analysis. This reduces computation time significantly in the downstream linked analysis because no modal stress and/or modal strain results are expanded again. The following options are available: – Program Controlled (default setting): Let the program choose whether or not the modal results are saved for possible downstream analysis. – No: Stress and strain results are not saved to file.mode for later use in the downstream linked analyses. This option is recommended for the linked harmonic analysis due to load generation, which requires that stresses and/or strains are expanded again as a result of the addition of elemental loads in the linked harmonic analysis. – For Future Analysis: Stress and strain results are saved to file.mode for later use in the downstream linked analyses. This option is recommended for a linked random vibration analysis. Choosing this option improves the performance and efficiency of the linked random vibration analysis because, with no load, there is no need for stress and strain expansion. • Expand Results From. – Linked Harmonic analyses. This field is displayed only when Stress and/or Strain and/or Calculate Reactions are set to Yes, implying that stress, strain, and reaction results are to be expanded and saved to file.mode after the load generation. Depending on the number of modes and number of frequency steps, you may want to save these modal stresses and/or strains after the load generation, which can be linearly superimposed to obtain harmonic stresses and/or strains at each frequency step. The following options are available: → Program Controlled (default setting): Let the program choose whether or not the stress, strain, and reaction results are expanded and saved for possible downstream analysis. When the Program Controlled option is chosen, one more read-only Details view entry (Expansion) will be shown. This in-

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Analysis Settings for Most Analysis Types dicates whether the stress, strain and reaction results are expanded from the modal solution or harmonic solution. → Harmonic Solution: Stress, strain, and reaction results are not expanded nor saved to file.mode after the load generation in the linked harmonic system. This option is recommended when the number of frequency steps is far less than the number of modes. In this option, the stress, strain, and/or reaction results are expanded from harmonic displacement at each frequency step. In this case, stress, strain, and/or reaction expansion is performed as many times as the number of frequency steps. → Modal Solution: Stress, strain, and reaction results are expanded and saved to file.mode after the load generation in the linked harmonic system. This option is recommended when the number of frequency steps is far more than the number of modes. In this option, the stress, strain, and/or reaction results are calculated by linearly combining the modal stresses, modal strains, and/or modal reactions expanded after the load generation. In this case, stress, strain, and/or reaction expansion are performed as many times as the number of modes. Refer to Recommended Settings for Modal and Linked Analysis Systems (p. 662) for further details. – Linked Transient analyses. This field is displayed only when Calculate Stress and/or Calculate Strain are set to Yes, implying that stress, strain and reaction results are to be expanded and saved to file.mode after the load generation. Depending on the number of modes and total number of sub steps/ time steps, you may want to save these modal stresses and/or strains after the load generation, which can be linearly superimposed to obtain transient stresses and/or strains at each time step. The following options are available: → Program Controlled (default setting): Let the program choose whether or not the stress and strain results are expanded and saved for possible downstream analysis. When the program controlled option is chosen, one more read only details view entry - - Expansion will be shown. This indicates whether the stress and strain results are expanded from modal solution or transient solution. → Transient Solution: Stress and strain results are not expanded nor saved to file.mode after the load generation in the linked transient analysis system. This option is recommended when the number of time steps accumulated over all the load steps is far less than the number of modes. In this option, the stress and/or strain results are expanded from transient displacement at each time step. In this case, stress and/or strain expansion is performed as many times as the number of time steps. → Modal Solution: Stress and strain results are expanded and saved to file.mode after the load generation in the linked transient system. This option is recommended when the number of time steps accumulated over all the load steps is far more than the number of modes. In this option, the stress and/or strain results are calculated by linearly combining the modal stresses and/or modal strains expanded after the load generation. In this case, stress and/or strain expansion are performed as many times as the number of modes. Refer to Recommended Settings for Modal and Linked Analysis Systems (p. 662) for further details.

Note • It is recommended that you not change Output Controls settings during a Solution Restart. Modifying Output Controls settings change the availability of the respective result type in the results file. Consequently, result calculations cannot be guaranteed for the entire solution. In addition, Result file values may not correspond to GUI settings in this scenario. Settings turned

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Configuring Analysis Settings off during a restart generate results equal to zero and may affect post processing of results and are therefore unreliable. • Modification of Stress, Strain, Nodal Force, Contact Miscellaneous, and General Miscellaneous will not invalidate the solution. If you want these output controls setting modification to be incorporated to your solution, please clean the solution first.

The above output controls are not step-aware, meaning that the settings are constant across multiple steps. In addition, the following settings are step-aware and allow you to define when data is calculated and written to the result file for Static Structural, Transient Structural, Rigid Dynamics, Steady-State thermal, and Transient Thermal analyses: • Store Results At. Specify this time to be All Time Points (default setting), Last Time Point, Equally Spaced Points or Specified Recurrence Rate. • Value. Displayed only if Store Results At is set to Equally Spaced Points or Specified Recurrence Rate. The controls that define when data is calculated are step aware, meaning that the settings can vary across multiple steps.

Recommended Settings for Modal and Linked Analysis Systems The following table provides a summary of recommended settings for Store Modal Results and Expand Results From based on the analysis type. Analysis Type

Recommended Store Modal Results Settings

Recommended Expand Results From Settings

Modal with no downstream linked analysis

No

Not available.

Modal with downstream linked Harmonic analysis

Stress and strain results not needed to be saved to file.mode because there is no downstream analysis. No

Harmonic Solution

Stress and strain results from modal analysis are overwritten by stresses and strains which are expanded again in the linked harmonic analysis due to any loads added in the downstream analysis.

Use when number of frequency steps are far less than the number of modes. This option is not available when the Modal analysis is Pre-Stress. Modal Solution Use when number of frequency steps are far more than the number of modes. This is the only option available when the Modal analysis is Pre-Stress.

Modal with downstream linked Ran662

For Future Analysis

Not available.

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Analysis Settings for Most Analysis Types Analysis Type

Recommended Store Modal Results Settings

dom Vibration analysis

Stress and strain results from modal analysis are expanded and used in the linked random vibration analysis. No stress or strain expansion is needed again because there is no load.

Modal with downstream linked Response Spectrum analysis

No

Recommended Expand Results From Settings

Not available.

Stress and strain results are always combined in response spectrum analysis using file.rst and file.mcom.

Note To evaluate summation of element nodal forces using FSUM in Command Snippet, it is required to save element nodal forces in modal to file.mode. Modal with downstream linked Transient analysis

No

Transient Solution

Stress and strain results from modal analysis are overwritten by stresses and strains which are expanded again in the linked transient analysis due to any loads added in the downstream analysis.

Use when number of time steps accumulated over all the load steps is far less than the number of modes. This option is not available when the Modal Analysis is Pre-Stress. Modal Solution Use when number of time steps accumulated over all the load steps is far more than the number of modes. This is the only option available when the Modal Analysis is PreStress.

Limitations When Using the Mechanical APDL Solver • The Mechanical application cannot post process split result files produced by the ANSYS solver. Try either of the following workarounds should this be an issue: – Use Output Controls to limit the result file size. Also, the size can more fully be controlled (if needed) by inserting a Commands object for the OUTRES command.

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Configuring Analysis Settings – Increase the threshold for the files to be split by inserting a Commands object for the /CONFIG,FSPLIT command.

Analysis Data Management The controls of the Analysis Data Management group vary based on the type of analysis being performed. Supported analysis types include: • Static Structural • Transient Structural • Rigid Dynamics • Harmonic • Modal • Linear Buckling • Random Vibration/Response Spectrum • Steady - State Thermal • Transient Thermal • Magnetostatic • Electric • Thermal Electric This grouping describes the options and specifications associated with the solution files. • Solver Files Directory: Indicates the location of the solution files for this analysis. The directory location is automatically determined by the program as detailed in File Management in the Mechanical Application (p. 1070). For Windows users, the solution file folder can be displayed using the Open Solver Files Directory feature. – Open Solver Files Directory Feature → This right-click context menu option is available when you have an analysis Environment or a Solution object selected. → Once executed, this option opens the operating system's (Windows Only) file manager and displays the directory that contains the solution files for your analysis. → The directory path is shown in the Details View. If a solution is in progress, the directory is shown in the Solver Files Directory field. When a solution is in progress, the directory displays in the Scratch Solver Files Directory. For a remote solve, it will open the scratch directory until the results download is complete. → This option is available on the Windows platform only.

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Analysis Settings for Most Analysis Types • Future Analysis: This property defines whether to use the results of the current analysis as loading or as an initial condition in a subsequent analysis. Shown below are the analysis types and their supported subsequent analysis choices. – Static Structural: options include None or Prestressed Analysis. If you link the supported analysis types, this property automatically defaults to the Prestressed Analysis setting. A Static Structural analysis can provide Pre-Stress effects for the following analysis types: → Pre-Stressed (Full) Harmonic Response → Pre-Stressed Modal – Linear Buckling: a Static Structural analysis is a prerequisite. – Modal: options include None or MSUP Analyses. When linked to a supported analysis type, as shown below, this property automatically defaults to the MSUP Analyses setting. A Modal analysis is a prerequisite for the following analysis types: → Random Vibration (PSD) → Response Spectrum • Scratch Solver Files Directory: This is a read-only indication of the directory where a solve “in progress” occurs. All files generated after the solution is done (including but not limited to result files) are then moved to the Solver Files Directory. The files generated during solves on My Computer or files requested from RSM for postprocessing during a solve remain in the scratch directory. For example, an early result file could be brought to the scratch folder from a remote machine through RSM during postprocessing while solving. With the RSM method, the solve may even be computed in this folder (for example, using the My Computer, Background SolveProcess Settings). The Mechanical application maintains the Scratch Solver Files Directory on the same disk as the Solver Files Directory. The scratch directory is only set for the duration of the solve (with either My Computer or My Computer, Background). After the solve is complete, this directory is set to blank. The use of the Scratch Solver Files Directory prevents the Solver Files Directory from ever getting an early result file. • Save MAPDL db: No (default setting) / Yes. Some Future Analysis settings will require the db file to be written. In these cases this field will be set to Yes automatically. • Delete Unneeded File: Yes (default setting) / No. If you prefer to save all the solution files for some other use you may do so by setting this field to No. • Nonlinear Solutions: Read only indication of Yes / No depending on presence of nonlinearities in the analysis. • Solver Units: You can select one of two options from this field: – Active System - This instructs the solver to use the currently active unit system (determined via the toolbar Units menu) for the very next solve. – Manual - This allows the you to choose the unit system for the solver to use by allowing them access to the second field, "Solver Unit System". Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Configuring Analysis Settings • Solver Units System: – If Active System is chosen for the Solver Units field, then this field is read-only and displays the active system. – If Manual is chosen for the Solver Units field, this field is a selectable drop-down menu. – If a Magnetostatic analysis is being performed, the field is read only because the only system available to solve the analysis is the mks system. – If a Thermoelectric or Electric analysis is being performed, only mks and µmks systems can be selected because they are the only systems currently allowed for these analyses.

Rotordynamics Controls The controls of the Rotordynamics Controls group vary based on the type of analysis being performed. Supported analysis types include: • Transient Structural • Harmonic • Modal The following settings control the items that apply to a rotating structure in a Modal Analysis. • Coriolis Effect - Set to On if Coriolis effects should be applied. On is a valid choice only if the Damped Solver Control is Yes. The default is Off. • Campbell Diagram - Set to On if Campbell diagram is to be plotted. The default is Off. On is a valid choice only if Coriolis Effect is turned On. • Number of Points - Indicates the number of solve points for the Campbell diagram. The default value is 2. A minimum of two (2) solve points is necessary. This property is only displayed when Campbell Diagram is set to On.

Visibility Allows you to selectively display loads in the Graph window by choosing Display or Omit for each available load type. A load must first be applied before the Visibility group becomes available/shown under Analysis Settings. The Visibility group is available for the following analysis types: • Static Structural • Transient Structural • Steady - State Thermal • Transient Thermal

Steps and Step Controls for Static and Transient Analyses The following topics are covered in this section: 666

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Steps and Step Controls for Static and Transient Analyses Role of Time in Tracking Steps, Substeps, and Equilibrium Iterations Automatic Time Stepping Guidelines for Integration Step Size

Role of Time in Tracking Time is used as a tracking parameter in all static and transient analyses, whether or not the analysis is truly time-dependent. The advantage of this is that you can use one consistent "counter" or "tracker" in all cases, eliminating the need for analysis-dependent terminology. Moreover, time always increases monotonically, and most things in nature happen over a period of time, however brief the period may be. Obviously, in a transient analysis time represents actual, chronological time in seconds, minutes, or hours. In a static analysis, however, time simply becomes a counter that identifies steps and substeps. By default, the program automatically assigns time = 1.0 at the end of step 1, time = 2.0 at the end of step 2, and so on. Any substeps within a step will be assigned the appropriate, linearly interpolated time value. By assigning your own time values in such analyses, you can establish your own tracking parameter. For example, if a load of 100 units is to be applied incrementally over one step, you can specify time at the end of that step to be 100, so that the load and time values are synchronous.

Steps, Substeps, and Equilibrium Iterations What is a step? A step corresponds to a set of loads for which you want to obtain a solution and review results. In this way every static or transient dynamic analysis has at least one step. However there are several scenarios where you may want to consider using multiple steps within a single analysis, that is, multiple solutions and result sets within a single analysis. A static or transient analysis starts at time = 0 and proceeds until a step end time that you specify. This time span can be further subdivided into multiple steps where each step spans a different time range. As mentioned in the Role of Time in Tracking (p. 667) section, each step spans a ‘time’ even in a static analysis.

When do you need Steps? Steps are required if you want to change the analysis settings for a specific time period. For example in an impact analysis you may want to manually change the allowable minimum and maximum time step sizes during impact. In this case you can introduce a step that spans a time period shortly before and shortly after impact and change the analysis settings for that step. Steps are also useful generally to delineate different portions of an analysis. For example, in a linear static structural analysis you can apply a wind load in the first step, a gravity load in the second step, both loads and a different support condition in the third step, and so on. As another example, a transient analysis of an engine might include load conditions corresponding to gravity, idle speed, maximum power, back to idle speed. The analysis may require repetition of these conditions over various time spans. It is convenient to track these conditions as separate steps within the time history. In addition steps are also required for deleting loads or adding new loads such as specified displacements or to set up a pretension bolt load sequence. Steps are also useful in setting up initial conditions for a transient analysis. Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Configuring Analysis Settings

How do you define steps? See the procedure, ”Specifying Analysis Settings for Multiple Steps” located in the Establish Analysis Settings (p. 134) section.

What are substeps and equilibrium iterations? Solving an analysis with nonlinearities requires convergence of an iterative solution procedure. Convergence of this solution procedure requires the load to be applied gradually with solutions carried out at intermediate load values. These intermediate solution points within a step are referred to as substeps. Essentially a substep is an increment of load within a step at which a solution is carried out. The iterations carried out at each substep to arrive at a converged solution are referred to as equilibrium iterations.

Load

Substep Load step

Final load value

1

2 Equilibrium iterations

Substeps

Automatic Time Stepping Auto time stepping, also known as time step optimization, aims to reduce the solution time especially for nonlinear and/or transient dynamic problems by adjusting the amount of load increment. If nonlinearities are present, automatic time stepping gives the added advantage of incrementing the loads appropriately and retreating to the previous converged solution (bisection) if convergence is not obtained. The amount of load increment is based on several criteria including the response frequency of the structure and the degree of nonlinearities in the analysis. The load increment within a step is controlled by the auto time stepping procedure within limits set by you. You have the option to specify the maximum, minimum and initial load increments. The solution will start with the “initial” increment but then the automatic procedure can vary further increments within the range prescribed by the minimum and maximum values. You can specify these limits on load increment by specifying the initial, minimum, and maximum number of substeps that are allowed. Alternatively, since a step always has a time span (start time and end time), you can also equivalently specify the initial, minimum and maximum time step sizes. Although it seems like a good idea to activate automatic time stepping for all analyses, there are some cases where it may not be beneficial (and may even be harmful): • Problems that have only localized dynamic behavior (for example, turbine blade and hub assemblies), where the low-frequency energy content of part of the system may dominate the high-frequency areas.

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Steps and Step Controls for Static and Transient Analyses • Problems that are constantly excited (for example, seismic loading), where the time step tends to change continually as different frequencies are excited. • Kinematics (rigid-body motion) problems, where the rigid-body contribution to the response frequency term may dominate.

Guidelines for Integration Step Size The accuracy of the transient dynamic solution depends on the integration time step: the smaller the time step, the higher the accuracy. A time step that is too large introduces an error that affects the response of the higher modes (and hence the overall response). On the other hand too small a time step size wastes computer resources. An optimum time step size can depend on several factors: 1. Response frequency: The time step should be small enough to resolve the motion (response) of the structure. Since the dynamic response of a structure can be thought of as a combination of modes, the time step should be able to resolve the highest mode that contributes to the response. The solver calculates an aggregate response frequency at every time point. A general rule of thumb it to use approximately twenty points per cycle at the response frequency. That is, if f is the frequency (in cycles/time), the integration time step (ITS) is given by: ITS = 1/(20f ) Smaller ITS values will be required if accurate velocity or acceleration results are needed. The following figure shows the effect of ITS on the period elongation of a single-DOF spring-mass system. Notice that 20 or more points per cycle result in a period elongation of less than 1 percent.

Period Elongation (%)

10 9 8 7 6 5 4 3 2 1 0

recommended 0 10 20 30 40 50 60 70 80 90 100 Number of Time Steps Per Cycle

2. Resolve the applied load-versus-time curve(s). The time step should be small enough to “follow” the loading function. For example, stepped loads require a small ITS at the time of the step change so that Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

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Configuring Analysis Settings the step change can be closely followed. ITS values as small as 1/180f may be needed to follow stepped loads. ü

ü Inpu Response

t

t

3. Resolve the contact frequency. In problems involving contact (impact), the time step should be small enough to capture the momentum transfer between the two contacting faces. Otherwise, an apparent energy loss will occur and the impact will not be perfectly elastic. The integration time step can be determined from the contact frequency (fc) as: c

c

=

π

where k is the gap stiffness, m is the effective mass acting at the gap, and N is the number of points per cycle. To minimize the energy loss, at least thirty points per cycle of (N = 30) are needed. Larger values of N may be required if velocity or acceleration results are needed. See the description of the Predict for Impact option within the Time Step Controls contact Advanced settings for more information. You can use fewer than thirty points per cycle during impact if the contact period and contact mass are much less than the overall transient time and system mass, because the effect of any energy loss on the total response would be small. 4. Resolve the nonlinearities. F