Ansys Modeling And Meshing Guide

ANSYS Modeling and
Meshing Guide
ANSYS Release 9.0
002114
November 2004
ANSYS, Inc. is a
UL registered
ISO 9001: 2000
Company.

ANSYS Modeling and Meshing Guide
ANSYS Release 9.0
ANSYS, Inc.
Southpointe
275 Technology Drive
Canonsburg, PA 15317
[email protected]
http://www.ansys.com
(T) 724-746-3304
(F) 724-514-9494

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Table of Contents
1. Overview of Model Generation ........................................................................................................... 1–1
1.1. What Is Model Generation? ........................................................................................................... 1–1
1.2. Typical Steps Involved in Model Generation Within ANSYS ............................................................ 1–1
1.2.1. Comparing Solid Modeling and Direct Generation ................................................................ 1–2
1.2.1.1. Solid Modeling ............................................................................................................ 1–2
1.2.1.2. Direct Generation ........................................................................................................ 1–3
1.3. Importing Solid Models Created in CAD systems ............................................................................ 1–3
2. Planning Your Approach ..................................................................................................................... 2–1
2.1. The Importance of Planning .......................................................................................................... 2–1
2.2. Determine Your Objectives ........................................................................................................... 2–1
2.3. Choose a Model Type (2-D, 3-D, etc.) ............................................................................................. 2–1
2.4. Choose Between Linear and Higher Order Elements ...................................................................... 2–1
2.4.1. Linear Elements (No Midside Nodes) ..................................................................................... 2–2
2.4.2. Quadratic Elements (Midside Nodes) .................................................................................... 2–3
2.5. Limitations on Joining Different Elements ..................................................................................... 2–6
2.6. Find Ways to Take Advantage of Symmetry ................................................................................... 2–6
2.6.1. Some Comments on Axisymmetric Structures ....................................................................... 2–7
2.6.1.1. Some Special Requirements for Axisymmetric Models .................................................. 2–7
2.6.1.2. Some Further Hints and Restrictions ............................................................................ 2–8
2.7. Decide How Much Detail to Include .............................................................................................. 2–8
2.8. Determine the Appropriate Mesh Density ..................................................................................... 2–8
3. Coordinate Systems ............................................................................................................................ 3–1
3.1. Types of Coordinate Systems ........................................................................................................ 3–1
3.2. Global and Local Coordinate Systems ............................................................................................ 3–1
3.2.1. Global Coordinate Systems .................................................................................................. 3–1
3.2.2. Local Coordinate Systems .................................................................................................... 3–2
3.2.3. The Active Coordinate System .............................................................................................. 3–4
3.2.4. Surfaces ............................................................................................................................... 3–5
3.2.5. Closed Surfaces and Surface Singularities ............................................................................. 3–6
3.3. Display Coordinate System ........................................................................................................... 3–7
3.4. Nodal Coordinate Systems ............................................................................................................ 3–8
3.4.1. Data Interpreted in the Nodal Coordinate System ................................................................. 3–8
3.5. Element Coordinate Systems ........................................................................................................ 3–9
3.6. The Results Coordinate System ..................................................................................................... 3–9
4. Using Working Planes ......................................................................................................................... 4–1
4.1. What Is a Working Plane? .............................................................................................................. 4–1
4.2. Creating a Working Plane .............................................................................................................. 4–1
4.2.1. Defining a New Working Plane ............................................................................................. 4–2
4.2.2. Controlling the Display and Style of the Working Plane ......................................................... 4–2
4.2.3. Moving the Working Plane ................................................................................................... 4–2
4.2.4. Rotating the Working Plane .................................................................................................. 4–3
4.2.5. Recreating a Previously-defined Working Plane .................................................................... 4–3
4.3. Working Plane Enhancements ....................................................................................................... 4–3
4.3.1. Snap Increment ................................................................................................................... 4–3
4.3.2. Display Grid ......................................................................................................................... 4–4
4.3.3. Retrieval Tolerance ............................................................................................................... 4–4
4.3.4. Coordinate Type .................................................................................................................. 4–4
4.3.5. Working Plane Tracking ........................................................................................................ 4–5
5. Solid Modeling .................................................................................................................................... 5–1
5.1. An Overview of Solid Modeling Operations ................................................................................... 5–1
ANSYS Modeling and Meshing Guide . ANSYS Release 9.0 . 002114 . © SAS IP, Inc.