ANSYS Modeling and Meshing Guide

1 ANSYS Modeling andMeshing GuideANSYS Release 2004 ANSYS , Inc. is aUL registeredISO 9001: Modeling and Meshing GuideANSYS Release , Technology DriveCanonsburg, PA 724-746-3304(F) 724-514-9494 Copyright and Trademark InformationCopyright 2004 SAS IP, Inc. All rights reserved. Unauthorized use, distribution or duplication is , DesignSpace, CFX, DesignModeler, DesignXplorer, ANSYS Workbench environment, AI*Environment, CADOE and any and all ANSYS , Inc. productnames referenced on any media, manual or the like, are registered trademarks or trademarks of subsidiaries of ANSYS , Inc. located in the United States orother countries.

2 ICEM CFD is a trademark licensed by ANSYS , Inc. All other trademarks and registered trademarks are property of their respective , Inc. is a UL registered ISO 9001: 2000 Inc. products may contain Patent No. 6,055, , Windows, Windows 2000 and Windows XP are registered trademarks of Microsoft and Mechanical Desktop are registered trademarks of Autodesk, is a registered trademark of SolidWorks is a registered trademark of Parametric Technology , Solid Edge and Parasolid are registered trademarks of Electronic Data Systems Corporation (EDS).ACIS and ACIS Geometric Modeler are registered trademarks of Spatial Technology, License Manager is a trademark of Macrovision ANSYS , Inc.

3 Software product and program documentation is ANSYS Confidential Information and are furnished by ANSYS , Inc. under an ANSYS software license agreement that contains provisions concerning non-disclosure, copying, length and nature of use, warranties, disclaimers and remedies,and other provisions. The Program and Documentation may be used or copied only in accordance with the terms of that license the ANSYS , Inc. online documentation or the ANSYS , Inc. documentation CD for the complete Legal this is a copy of a document published by and reproduced with the permission of ANSYS , Inc., it might not reflect the organization or physical appearanceof the original.

4 ANSYS , Inc. is not liable for any errors or omissions introduced by the copying process. Such errors are the responsibility of the partyproviding the of Contents1. Overview of Model Generation .. 1 What Is Model Generation? .. 1 Typical Steps Involved in Model Generation Within ANSYS .. 1 Comparing Solid Modeling and Direct Generation .. 1 Solid Modeling .. 1 Direct Generation .. 1 Importing Solid Models Created in CAD systems .. 1 32. Planning Your Approach .. 2 The Importance of Planning .. 2 Determine Your Objectives .. 2 Choose a Model Type (2-D, 3-D, etc.) .. 2 Choose Between Linear and Higher Order Elements.

5 2 Linear Elements (No Midside Nodes) .. 2 Quadratic Elements (Midside Nodes) .. 2 Limitations on Joining Different Elements .. 2 Find Ways to Take Advantage of Symmetry .. 2 Some Comments on Axisymmetric Structures .. 2 Some Special Requirements for Axisymmetric Models .. 2 Some Further Hints and Restrictions .. 2 Decide How Much Detail to Include .. 2 Determine the Appropriate Mesh Density .. 2 83. Coordinate Systems .. 3 Types of Coordinate Systems .. 3 Global and Local Coordinate Systems .. 3 Global Coordinate Systems .. 3 Local Coordinate Systems .. 3 The Active Coordinate System.

6 3 Surfaces .. 3 Closed Surfaces and Surface Singularities .. 3 Display Coordinate System .. 3 Nodal Coordinate Systems .. 3 Data Interpreted in the Nodal Coordinate System .. 3 Element Coordinate Systems .. 3 The Results Coordinate System .. 3 94. Using Working Planes .. 4 What Is a Working Plane? .. 4 Creating a Working Plane .. 4 Defining a New Working Plane .. 4 Controlling the Display and Style of the Working Plane .. 4 Moving the Working Plane .. 4 Rotating the Working Plane .. 4 Recreating a Previously-defined Working Plane .. 4 Working Plane Enhancements .. 4 Snap Increment.

7 4 Display Grid .. 4 Retrieval Tolerance .. 4 Coordinate Type .. 4 Working Plane Tracking .. 4 55. Solid Modeling .. 5 An Overview of Solid Modeling Operations .. 5 1 ANSYS Modeling and Meshing Guide . ANSYS Release . 002114 . SAS IP, Creating Your Solid Model from the Bottom Up .. 5 Keypoints .. 5 Hard Points .. 5 Lines .. 5 Areas .. 5 Volumes .. 5 Extruding Volumes .. 5 Sweeping Volumes .. 5 Creating Your Solid Model from the Top Down: Primitives .. 5 Creating Area Primitives .. 5 Creating Volume Primitives .. 5 Creating a Torus or Toroidal Sector .. 5 Sculpting Your Model with Boolean Operations.

8 5 Boolean Operation Settings .. 5 Entity Numbering After Boolean Operations .. 5 Intersect .. 5 Illustrations of Intersection Operations .. 5 Pairwise Intersect .. 5 Illustrations of Pairwise Intersection Operations .. 5 Add .. 5 Illustrations of Addition Operations .. 5 Subtract .. 5 Illustrations of Subtraction Operations .. 5 Working Plane Subtract .. 5 Illustrations of Working Plane Subtraction Operations .. 5 Classify .. 5 Overlap .. 5 Illustrations of Overlap Operations .. 5 Partition .. 5 Illustrations of Partition Operations .. 5 Glue (or Merge) .. 5 Illustrations of Glue Operations.

9 5 Alternatives to Boolean Operations .. 5 Updating after Boolean Operations .. 5 Moving and Copying Solid Model Entities .. 5 Generating Entities from a Pattern .. 5 Generating Entities by Symmetry Reflection .. 5 Transferring a Pattern of Entities to a Coordinate System .. 5 Scaling Solid Model Entities .. 5 Solid Model Loads .. 5 Transferring Solid Model Loads .. 5 Displaying Load Symbols .. 5 Turning Off Large Symbols for Node and Keypoint Locations .. 5 Selecting a Format for the Graphical Display of Numbers .. 5 Listing Solid Model Loads .. 5 Mass and Inertia Calculations.

10 5 Considerations and Cautions for Solid Modeling .. 5 Representation of Solid Model Entities .. 5 When a Boolean Operation Fails .. 5 Degeneracies .. 5 Graphically Identifying Degeneracies .. 5 Listing the Keypoints Associated with Degeneracies .. 5 56 ANSYS Modeling and Meshing Guide . ANSYS Release . 002114 . SAS IP, Modeling and Meshing Discontinuities .. 5 Other Causes of Boolean Failures .. 5 Some Suggested Corrective Actions .. 5 Other Hints .. 5 Avoid Regions that Cross over Themselves .. 5 Use ANSYS Parameters .. 5 Consider Alternatives to Boolean Commands .. 5 Work with Lower-Dimension Constructions.