UGS NX 4 ADVANCED SIMULATION.pdf

8/17/2019 UGS NX 4 ADVANCED SIMULATION.pdf

1/216

Applications of Advanced Simulation

Student GuideJuly 2006

MT15020 — NX4.0.2

Publication Number

mt15020_g NX 4


2/216

Copyright and trademarks

Proprietary and Restricted Rights Notices

This software and all related documentation are proprietary to UGS Corp.

Copyright

©2006 UGS Corp. All Rights Reserved.

All trademarks belong to their respective holders.

©2006 UGS Corporation

All Rights Reserved.

Produced in the United States of America.

2 A pplications of Advanced Simulation — Student Guide mt15020_g NX 4


3/216

Contents

Course overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Course description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Intended audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9How to use this manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Symbols used in this guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Advanced Simulation overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1- 1 Advanced Simulation file structure . . . . . . . . . . . . . . . . . . . . . . . . . 1- 2 Advanced Simulation workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1- 4Simulation Navigator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1- 5

Nodes in the Simulation Navigator . . . . . . . . . . . . . . . . . . . . . . 1- 6Simulation File View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1- 8

Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10

Geometry idealization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Geometry idealization overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 1Modifying features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 1

Edit Feature Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 2Suppress Feature/Unsuppress Feature . . . . . . . . . . . . . . . . . . . . 2- 2Master Model Dimension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 5

Modifying geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 7Idealize Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 7Defeature Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10Partition Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11Midsurface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14Face Pair midsurface method . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15

Offset midsurface method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16User Defined midsurface method . . . . . . . . . . . . . . . . . . . . . . . . 2-18Sew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19Subdivide Face . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22

Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23

3D meshing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3D Tetrahedral Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3- 1

©UGS Corporation, All Rights Reserved Applications of Advanced Simulation — Student Guide 3


4/216

Contents

3D Swept Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3- 4Solid from Shell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3- 6

Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3- 8Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3- 8

2D meshing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

2D meshing overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 1Editing a 2D mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 4


1D and 0D meshing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

1D Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5- 11D element meshing methods . . . . . . . . . . . . . . . . . . . . . . . . . . 5- 2

Create Weld Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5- 51D Element Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5- 70D Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5- 9

Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11

Mesh points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

Mesh points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6- 1 Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6- 2Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6- 2

Mesh and object display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1Mesh Display preferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7- 1Object display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7- 2


Geometry abstraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1

Geometry abstraction overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8- 1Comparing geometry idealization and geometry abstraction . . . . . . 8- 2Understanding polygon geometry . . . . . . . . . . . . . . . . . . . . . . . . . . 8- 2

Understanding the geometry abstraction process . . . . . . . . . . . . . . . 8- 3Fillet identification process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8- 6 Auto Heal Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8- 9Split Edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-10Split Face . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-11Merge Edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-13Merge Face . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-13Match Edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-14Collapse Edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-17Face Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-19

4 Applications of Advanced Simulation — Student Guide ©UGS Corporation, All Rights Reserved mt15020_g NX 4


5/216

Contents

Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-20 Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-21Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-21

Element attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1Element attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9- 1

Attribute Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9- 3 Attribute Editor – point selection . . . . . . . . . . . . . . . . . . . . . . . . 9- 3 Attribute Editor – curve/element selection . . . . . . . . . . . . . . . . . 9- 4 Attribute Editor – face selection . . . . . . . . . . . . . . . . . . . . . . . . 9- 6 Attribute Editor – body selection . . . . . . . . . . . . . . . . . . . . . . . . 9- 7 Attribute Editor – 3D mesh selection . . . . . . . . . . . . . . . . . . . . . 9- 8 Attribute Editor – 2D mesh selection . . . . . . . . . . . . . . . . . . . . . 9- 9 Attribute Editor – 1D mesh selection . . . . . . . . . . . . . . . . . . . . . 9-10 Attribute Editor – 0D mesh selection . . . . . . . . . . . . . . . . . . . . . 9-11

Attribute Editor – Contact mesh selection . . . . . . . . . . . . . . . . . 9-13 Attribute Editor – Surface contact mesh selection . . . . . . . . . . . 9-15

Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-16Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-16

Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

Materials overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10- 2Customizing the material library . . . . . . . . . . . . . . . . . . . . . . . . . 10- 4

Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10- 5Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10- 5

Boundary conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-1

Boundary conditions overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11- 2Supported boundary conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 11- 2Creating loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11- 5Creating constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11- 6


Model information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-1

Model information overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12- 2

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12- 4

Model checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-1

Model Check overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13- 2Comprehensive check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13- 2Element Shapes check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13- 3Element Shapes Threshold Values . . . . . . . . . . . . . . . . . . . . . . . . 13- 3Element Outlines check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-10Nodes check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-10



6/216

Contents

2D Element Normals checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-11Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-11

Solving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-1

Solving overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14- 2Solving the model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14- 2

Analysis Job Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14- 3Batch solving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14- 3


Post-processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-1

Post-processing introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15- 2Results in the Simulation Navigator . . . . . . . . . . . . . . . . . . . . . . . 15- 2

The Post Control toolbar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15- 3Import Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15- 4Post View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15- 6Post view templates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15- 7Post view layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15- 7Overlay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15- 8Combining load cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15- 9

Animation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-10Identify . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-10Generating reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-12

Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-12

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-12

Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-1

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16- 2Creating the report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16- 4Exporting the report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16- 4


Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-1

Units overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17- 2

Units Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17- 2Units Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17- 4


Mesh connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-1

Mesh Mating Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18- 2Edge Face Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18- 5Weld Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18- 6



7/216

Contents

Contact Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18- 9Surface Contact Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-10

Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-11Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-11

Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19-1

Optimization overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19- 2Optimization Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19- 2Optimization analysis options . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19- 3Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19- 4Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19- 5Design Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19- 6


Durability (fatigue) analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-1

Durability overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20- 2Preparing the model for a durability analysis . . . . . . . . . . . . . . . . 20- 2Creating a durability solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20- 3Evaluating fatigue results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20- 4


Buckling analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21-1

Linear buckling overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21- 2

Loads in linear buckling analysis . . . . . . . . . . . . . . . . . . . . . . . . . 21- 2Supported environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21- 3


Modal analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22-1

Modal analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22- 2 Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22- 4Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22- 5

Thermal analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23-1Thermal analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23- 2


Contact and gluing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24-1

Surface to Surface Contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24- 2 Advanced Nonlinear Contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24- 3Surface to Surface Gluing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24- 5



8/216

Contents

Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24- 6Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24- 6



9/216

Course overview

Course description

Applications of Advanced Simulation introduces the finite element modeling and analysis tool integrated in NX. It is intended for design engineers andanalysts who want to learn the details of how to do finite element analysis onNX models. This course covers the details of the FEA processes from modelpreparation, mesh generation and manipulation, material definition, loadsand boundary conditions, FEA model checking and solving, to postprocessing

the results.

Intended audience

• Design engineers

• Analysts

Prerequisites

• Practical Applications of NX course or self-paced equivalent.

• Working knowledge of NX Modeling.

• Basic understanding of finite element analysis principles.

How to use this manual

The general format for lesson content is:

• presentation

• activity in the Applications of Advanced Simulation Workbook

• summary

It is important that you use the Student Guide and Workbook in the sequencepresented. Later lessons assume you have learned concepts and techniquestaught in earlier lessons. If necessary, you can always refer to any previousactivity where a method or technique was originally taught.



10/216

How to use this manual

Symbols used in this guide

The following symbols are used throughout this guide:

This is a tip.

This is a note.

This is a warning.



11/216

Lesson

1 Introduction

Objective

• This lesson is a fundamental introduction to Advanced Simulation.

Advanced Simulation overview

Advanced Simulation is a comprehensive finite element modeling and results visualization product that is designed to meet the needs of experiencedanalysts. Advanced Simulation includes a full suite of pre-and post-processing tools and supports a broad range of product performance evaluation solutions.

Advanced Simulation provides seamless, transparent support for a numberof industry-standard solvers, such as NX Nastran, MSC Nastran, ANSYS,and ABAQUS. For example, when you create either a mesh or a solution in

Advanced Simulation, you specify the solver you plan to use to solve yourmodel and the type of analysis you want to perform. The software thenpresents all meshing, boundary conditions, and solution options using theterminology or “language” of that solver and analysis type. Additionally, you

©UGS Corporation, All Rights Reserved Applications of Advanced Simulation — Student Guide 1-1


12/216

Introduction

can solve your model and view your results directly in Advanced Simulationwithout having to first export a solver file or import your results.

Advanced Simulation provides all the functionality available in DesignSimulation, plus numerous additional features that support advancedanalysis processes.

• Advanced Simulation features data structures, such as the separateSimulation and FEM files, that help facilitate the development of FEmodels across a distributed work environment. These data structuresalso allow analysts to easily share FE data to perform multiple typesof analyses.

• Advanced Simulation offers world class meshing capabilities. Thesoftware is designed to produce a very high quality mesh while using an economic element count. Advanced Simulation supports a complete

complement of element types (0D, 1D, 2D, and 3D). Additionally, AdvancedSimulation gives analysts control over specific meshing tolerances whichcontrol, for example, how the software meshes complex geometry, suchas fillets.

• Advanced Simulation includes a number of geometry abstraction toolsthat give analysts the ability to tailor the CAD geometry to the needs of their analysis. For example, analysts can use these tools to improve theoverall quality of their mesh by eliminating problematic geometry, such astiny edges.

• Advanced Simulation features the new NX Thermal and NX Flow solvers.– NX Thermal is a fully integrated finite difference solver. It allows

thermal engineers to predict heat flow and temperatures in systemssubjected to thermal loads.

– NX Flow is a Computational Fluid Dynamics (CFD) solver. It allowsanalysts to perform steady-state, incompressible flow analysis andpredict flow rates and pressure gradients for movement of fluid in asystem.

You can use NX Thermal and NX Flow together to perform coupled

thermal/ flow analyses.

Advanced Simulation file structure

As you progress through the Advanced Simulation workflow, you will use fourseparate, yet associated, files to store information. To work ef ficiently in

Advanced Simulation, you need to understand what data is stored in whichfile, and thus which file needs to be the active work part when you create thatdata. These four files parallel the simulation process.

1-2 Applications of Advanced Simulation — Student Guide ©UGS Corporation, All Rights Reserved mt15020_g NX 4


13/216

Introduction

The original design part file being analyzed

A part file has a .prt extension. For example, a part might be named plate.prt.

The part file contains the master part or an assembly, and the unmodifiedpart geometry.

If you start with a model designed by someone else, you might not havepermission to modify it. The master part file is generally not modifiedduring the analysis process.

The idealized copy of the design part file

An idealized part has a .prt extension. By default, when an idealizedpart file is created, fem#_i is appended to the part name. For example,an idealized part would be named plate_fem1_i.prt if the original partwas named plate.prt.

An idealized part is an associative copy of the original, and you canmodify it.

The idealization tools let you make changes to the design features of themodel using the idealized part. You can perform geometry idealization

as needed on the idealized part without modifying the master part. Forexample, you may remove and suppress features such as small geometrydetails that can be ignored in the analysis.

You can use multiple idealized files for different types of analysis of thesame original design part file.

The FEM file



14/216

Introduction

A FEM file has a .fem extension. By default, when a FEM file is created,_fem# is appended to the part name. For example, a FEM file may benamed plate_fem1.fem if the original part was named plate.prt.

A FEM file contains the mesh (nodes and elements), physical properties,and materials.

Once you create the mesh, you can use the abstraction tools to removedesign artifacts that can affect the overall quality of the mesh such assliver faces, small edges, and isthmus conditions. The abstraction toolsallow you to mesh the geometry at a level of detail that suf ficientlycaptures the design intent relevant to a particular finite element analysis.

The geometry abstraction occurs on polygon geometry stored in the FEM,not in the idealized or master part.

Since multiple FEM files can reference the same idealized part, you can

build different FEMs f or different types of analyses.

The Simulation file

A Simulation file name has a .sim extension. By default, when aSimulation file is created, _sim# is appended to the part name. Forexample, a Simulation file may be named plate_sim1.sim if the originalpart was named plate.prt.

The Simulation file contains all the simulation data, such as solutions,solution setup, loads, constraints, element-associated data, physical

properties, and overrides. You can create many Simulation fi

les associatedto the same FEM file.

Advanced Simulation workflow

Before you begin an analysis, you should have a thorough understanding of the problem you are trying to solve. You should know which solver you will beusing, what type of analysis you are performing, and what type of solution isneeded. The following outline summarizes the general workflow in AdvancedSimulation.

1. In NX, open a part file.

2. Open the Advanced Simulation application.

Specify the default solver (which sets the environment, or language) forworking in the FEM and Simulation files.

You could also choose to create only the FEM file first, and thencreate a Simulation file later.

3. Create a solution.



15/216

Introduction

Select the solver (such as NX Nastran), analysis type (such as Structural),and solution type (such as Linear Statics).

4. If necessary, idealize the part geometry.

Once you make the idealized part active, you can remove unnecessarydetails such as holes or fillets, partition the geometry to prepare for solidmeshing, or create midsurfaces.

5. Make the FEM file active, and mesh your geometry.

It is a good practice to first mesh your geometry automatically using thesoftware defaults. In the great majority of cases, the software defaultsprovide a robust, high-quality mesh you can use without modification.

6. Check your mesh quality.

If necessary, you can refine your mesh by returning to the idealized partand further idealizing the part geometry. In addition, in the FEM you canuse the abstraction tools to eliminate issues with the CAD geometry thatcan cause undesirable results when you mesh your model.

7. Apply a material to the mesh.

8. When you are satisfied with your mesh, make the Simulation file active,and apply loads and constraints to your model.

9. Solve your model.

10. Examine your results in Postprocessing.

Simulation Navigator

The Simulation Navigator provides you with a graphical way of viewing andmanipulating the different files and components of a CAE analysis within atree structure. Each file or component is displayed as a separate node inthe tree.

The Simulation Navigator provides direct access to the entities in it throughshortcut menus. You can perform most operations directly in the SimulationNavigator instead of using icons or commands. For example, to create a newsolution definition, you can drag loads and constraints from one container toanother in the Simulation Navigator .



16/216

Introduction

Nodes in the Simulation Navigator

The top panel of the Simulation Navigator shows the contents of the displayed

file. The figure below shows an example of the containers that can bedisplayed within a top-level Simulation file. The check boxes let you controlthe display of the items.



17/216

Introduction

The following table presents a high-level overview of the various nodes in theSimulation Navigator .

Icon Node Name Node Description

Simulation Contains all the simulation data, such assolutions, solution setup, solver-specificsimulation objects, loads, constraints, andoverrides. You can have multiple Simulationfiles associated with a single FEM file.

FEM Contains all the mesh data, physical properties,material data, and polygon geometry. The FEMfile is always associated to the idealized part.

You can associate multiple FEM files to a singleidealized part.

idealized part Contains the idealized part that the softwarecreates automatically when you create a FEM.

master part When the master part is the work part,right-click on the master part node to create anew FEM or display existing idealized parts.

PolygonGeometry

Contains the polygon geometry (polygon bodies,faces, and edges). Once you mesh the FEM,any further geometry abstraction occurs onthe polygon geometry, not the idealized or themaster part.

0D Meshes Contains all 0D meshes.1D Meshes Contains all 1D meshes.

2D Meshes Contains all 2D meshes.

3D Meshes Contains all 3D meshes.

SimulationObject

Container

Contains solver- and solution-specific objects,such as thermostats, tables, or flow surfaces.

Load

Container

Contains loads assigned to the current

Simulation file. In a Solution container, theLoad Container contains the loads assigned togiven subcase.

ConstraintContainer

Contains constraints assigned to the currentSimulation file. In a Solution container, theConstraint Container contains the constraintsassigned to the solution.



18/216

Introduction

Icon Node Name Node Description

Solution Contains the solution objects, loads, constraints,and subcases for the solution.

SubcaseStep

Contains solution entities specific to eachsubcase within a solution, such as loads,constraints, and simulation objects.

Results Contains any results from a solve. In the postprocessor, you can open the Results node and usethe visibility check boxes within the SimulationNavigator to control the display of variousresults sets.

Simulation File View

The bottom section of the Simulation Navigator contains the Simulation FileView panel, which shows the overall “roadmap” of the files you have open. Towork on a particular file, double-click it make it active.



19/216

Introduction

Part file bracket.prt

Idealized part file bracket_fem_i.prt

FEM file bracket_fem1.fem

Simulation file bracket_sim1.sim



20/216

Introduction

Activity

See the “Introduction” activity in the Applications of Advanced SimulationWorkbook.

In this activity you will work through the Advanced Simulation workflow byanalyzing a part — a connecting rod — using a 3D (solid) mesh.

Summary

In this lesson you:

• Learned about the capabilities of Advanced Simulation.

• Learned about the files that are used by Advanced Simulation.

• Learned about basic workflow for using Advanced Simulation.

• Created FEM and Simulation files.

• Worked with files in the Simulation Navigator .

• Worked through the finite element analysis workflow in AdvancedSimulation.



21/216

Lesson

2 Geometry idealization

Objective

• Learn how to use model preparation tools to simplify your model beforemeshing.

Geometry idealization overviewGeometry idealization is the process of removing or suppressing features fromyour model prior to defining a mesh. You can also use geometry idealizationcommands to create additional features, such as partitions, to supportyour finite element modeling goals. For example, you can use geometryidealization commands to:

• Remove features, such as bosses, that aren’t significant to your analysis.

• Modify the dimensions of the idealized part using interpart expressions.

• Partition a larger volume into multiple smaller volumes to facilitatemapped meshing.

• Create midsurfaces to facilitate shell meshing of thin-walled parts.

The software performs all geometry idealization operations on the idealizedpart, which is an assembly instance of your master model. No idealization isperformed directly on the master model.

You can use the commands on the Model Preparation toolbar to idealize thegeometry in your model.

To use the commands on the Model Preparation toolbar, you mustmake the idealized part the displayed part.

Modifying features

Several tools let you modify features of the idealized part:

• Edit Feature Parameters

• Suppress Feature and Unsuppress Feature



22/216

2

Geometry idealization

• Master Model Dimension

Edit Feature Parameters

In Advanced Simulation, when you use the Midsurface tool, you createa midsurface feature parameter that you can edit using Edit Feature

Parameters .

Additionally, you can edit any existing feature parameters in your modelbased on the method and parameter values used when it was created. Theinteraction depends on the type of feature you select.

Suppress Feature/Unsuppress Feature

Use Suppress Feature to automatically select features to besuppressed, or to manually select one or more features and temporarilyremove them from the target body and the display.

To successfully access features for suppression, you must first enablesuppression for the relevant part features in Modeling (Modeling application→ Edit→ Feature→ Suppress by Expression).



23/216


A suppressed feature still exists in the database but appears to be removedfrom the model. You can retrieve any suppressed features using Unsuppress

Feature .

Use Suppress Feature to:

• Reduce the size of large models, thereby reducing the creation, objectselection, edit, and display time.

• Remove non-critical features such as small holes, blends, and chamfersfrom your model for analysis work. Note that suppressed features are notmeshed in Advanced Simulation.

• Create features in locations where there is conflicting geometry. Forexample, if you need to position a feature using an edge that has alreadybeen blended, you do not need to delete the blend. You can suppress theblend, create and position the new feature, and then unsuppress the blend.

UGS recommends that you do not create new features where asuppressed feature exists.



24/216

2


Suppressing associated features

When you suppress a feature that has associated features, the associatedfeatures are also suppressed (see figure below).



25/216


Suppressing features

1. Click Suppress Feature .

2. Select the feature(s) to be suppressed, either from the list in the dialog orin the graphics window. You can also click the Selection Criteria buttonfor automatic selection of suppressable features using a criteria filter.

3. If you do not want the Suppress Feature selection dialog to include anydependents in the Selected Features list, turn the List Dependents toggleswitch to Off . (Doing so can noticeably improve performance time if theselected features have a lot of dependents.)

4. Click OK or Apply to suppress the selected features.

Master Model Dimension

The Master Model Dimension tool launches the Edit Dimension dialog box. Edit Dimension lets you modify the idealized part’s dimensions, taking advantage of interpart expressions. Use the Edit Dimension dialog box tomodify any feature or sketch dimension without affecting the master partdimensions.



26/216

2


Editing master model dimensions

1. Click Master Model Dimension to open the Edit Dimension dialog and select a feature. Associated expressions or descriptions display inthe list window.



27/216


2. Use the Expression or the Description option to display the selectedfeature’s dimensions as either an interpart expression or as standarddescriptions for the feature type.

3. Select a dimension from the list to modify.

4. (Optional) Click Used By to view a list of where the selected expressionis used.

5. Enter a new value for the selected dimension.

6. Click Apply to apply the new dimension value, and repeat steps 3 – 5 forthe remaining features and dimensions. Click OK to apply the new valueand close the Edit Dimensions dialog.

Modifying geometry

Several tools let you modify the geometry of the idealized part:

• Idealize Geometry

• Defeature Geometry

• Partition Model

• Midsurface

• Sew

• Subdivide Face

Idealize Geometry

Use Idealize Geometry to simplify a model’s geometry by removing features from a body or a region of a body that satisfy certain criteria, orthat you explicitly select for removal. For example, you may want to removesmall geometric features that would otherwise cause too many additionalelements to be created.

To use Idealize Geometry , you must have the idealized partdisplayed in the graphics window.



28/216

2


Idealizing Geometry on a Body

1. With the idealized part displayed in the graphics region, click Idealize

Geometry .

2. In the Idealize dialog, click Body .

3. In the graphics window, select the body.

You can now select options that identify features to be removed.

4. (Optional) To remove specific faces, click Removed Faces (Optional)

, and select faces to remove.

5. (Optional) To remove blends, select Chain Selected Blends. In thegraphics window, select a blend.

The software selects adjacent blends with the same radius.



29/216


6. (Optional) To automatically remove features, select Holes or Blends inAutomatic Feature Removal. Enter a value for the criteria.

The software selects all features in the body that meet the criteria.

7. Click OK.

The selected features are removed.

Idealizing Geometry in a Region

1. With the idealized part displayed, click Idealize Geometry .

2. In the Idealize dialog, click Region .

3. In the graphics window, select a seed face (the first face in the region).

You can now select features to be removed.

4. (Optional) To define an outer boundary for the region, click Boundary

Faces (Optional) and select the face or a set of faces.

5. (Optional) To automatically select adjacent faces to include in the region,select Tangential Edge Angle, and enter an angle value.

The software selects faces adjacent to the seed face if the angle betweenthe normal to the seed face and the normal of an adjacent face is lessthan or equal to the angle value.

6. (Optional) To remove specific faces, click Removed Faces (Optional)

, and select faces to remove.

7. (Optional) To remove blends, turn on Chain Selected Blends. Selecta blend.

The software selects the adjacent blends with the same radius.

8. Click Preview Region to see the outline of the region to be simplified.

9. (Optional) To automatically remove features, select Holes or Blends inAutomatic Feature Removal. Enter a value for the criteria.

The software selects all features that meet the criteria.

10. Click OK.



30/216

2


All selected features are removed.

Defeature Geometry

Defeature Geometry provides a streamlined method for featureremoval. When you defeature a model, you simplify geometry by using selections in the graphics window to remove a face or set of faces. This is aquick way to remo ve larger model features such as bosses containing multiplefaces.

Defeaturing geometry

To remove a feature or set of features, follow these basic steps:

1. Click Defeature Geometry .

If the Selection Intent toolbar is not visible in the graphicswindow, position the cursor in the toolbar area outside thegraphics window and click MB3 to enable Selection Intent.

2. Select Add Region Boundary from the Face drop-down list in SelectionIntent.

In the graphics window, the cursor becomes available for face selection.

3. Select a seed face for the feature you want to remove.

4. Select a boundary face as the outer limit for feature removal.

5. Click MB2 to update the surface region. The second figure in the following graphic shows an example of a resulting surface region.

6. Click on the Defeature dialog bar, or click MB2 again to executefeature removal.

To edit the removed feature, click on the Part Navigator tab in the ResourceBar and locate the Defeature node. Use MB3 menu options to edit featureparameters.



31/216


Partition Model

Partition Model provides a way to associatively partition solid bodies ina simulation model. This feature is most often used to partition bodies intosweepable solids to create a swept mesh model.

This feature creates a named group of features, which can be seen in themodel navigation tool. The objects selected for the trimming operation

determine the contents of the named feature. Furthermore, the groupedfeature allows users much greater flexibility in editing.

In addition to the geometric operation of splitting the body, a glued meshmating condition is automatically created at the partitioning geometrylocation, so that applied meshes are continuous from one body to the other.

The model partitioning function is also useful for controlling a tetrahedralmesh using, for example, different global element sizes on sub-bodies.Because of this, the geometry model needs to be broken down into smallerunits that can be more easily and automatically meshed. Model partitioning breaks down a volume into sub-volumes associatively.



32/216

2


Partition Model provides a way to associatively partition solid bodies ina simulation model. This feature is most often used to partition bodies intosweepable solids to create a swept mesh model.

This feature creates a named group of features, which can be seen in themodel navigation tool. The objects selected for the trimming operationdetermine the contents of the named feature. Furthermore, the groupedfeature allows users much greater flexibility in editing.

In addition to the geometric operation of splitting the body, a glued meshmating condition is automatically created at the partitioning geometry

location, so that applied meshes are continuous from one body to the other.The model partitioning function is also useful for controlling a tetrahedralmesh using, for example, different global element sizes on sub-bodies.Because of this, the geometry model needs to be broken down into smallerunits that can be more easily and automatically meshed. Model partitioning breaks down a volume into sub-volumes associatively.



33/216


Partitioning the model

1. Click Partition Model .

The Partition Model dialog is displayed.

2. Click Body to Partition and select the solid body to be partitioned.

3. Click Partitioning Geometry , and select the desired partitiongeometric tool (datum plane, sheet body, curve/edge, etc.) to subdividethe body or bodies. Select an option from the Filter drop-down menu toaid in selection.

When Blank Partition Geometry is selected (the default), partitioning geometry is blanked following the partitioning operation.



34/216

2


4. If necessary, click Direction and choose a Vector Method to define adirection vector to extrude or revolve a selected section.

5. Click Apply to create the partition.

If you are partitioning the model to prepare for swept meshing,

click Show Unsweepable Solids to highlight bodies thatrequire further partitioning.

Repeat steps 2 – 4 to fully partition the model.

Midsurface

Use Midsurface to simplify thin-walled geometry and create acontinuous surface feature that resides between two opposing faces within asingle solid body. The points and normals of the parent faces (surface pairs)are averaged at corresponding parameters. The new surface, or midsurface,contains information about the geometric thickness of the surface pairs.

Midsurface creation methods

Use one of the following methods to create a midsurface feature:

• Face Pair : This method creates a midsurface halfway between theopposing face pairs. The face pair method is useful for creating midsurfaces for thin-wall geometries with ribs.

• Offset: This method offsets the midsurface from one side of the solid bodyby a depth ranging from 0 to 100% (the thickness of the solid).



35/216


• User Defined: This method defines a sheet body you’ve previously createdas the midsurface of a part. That is, you can manually model a sheet bodyto approximate the midsurface of a thin-walled part, and then define thatbody as a midsurface feature of your part.

Face Pair midsurface method

The Face Pair method uses opposing face pairs to create a midsurface locatedhalfway between the two faces. This type of midsurface can only be createdfrom a single solid body that contains opposing faces.

Automatically Creating a Face Pair

1. Click Midsurface .

2. In the dialog, choose Method →Face Pair .



36/216

2


3. Select a face for side one and click MB2.

Note that the solid body is promoted at this point.

4. Choose AutoCreate.The software creates as many face pair features as possible.

5. Manually define or edit any remaining face pair features, if necessary.

Manually Creating a Face Pair Midsurface


2. In the dialog, choose Method →Face Pair .

3. Select a face for side one and click MB2. Note that the solid body ispromoted at this point.

4. Select an opposing face for side 2.

Alternatively, select the Automatic Progression check box. When thisoption is turned on, the software selects the most likely side 2 face foreach side 1 face you select.

5. Continue to select pairs in this manner until all face pair featuresare defined. Watch the cue line to ensure that you select the correctcorresponding face at the right time.

Offset midsurface method

With the Offset method, a midsurface generated from a seed face is positionedmidway between the seed face and its opposing face. The distance betweenthe seed face and the opposing face is the thickness of the solid. The offsetmethod requires a solid of uniform thickness.

You can define any number of faces to be offset, but you first must selecta seed face.

Once you begin, you cannot switch from the offset method to the facepair method.

The midsurface thickness created using the offset method is added as an NX attribute attached to the midsurface sheet body. The name of the attributeis "Midsurface_thickness." You can verify the thickness using Format →Attribute → Object.



37/216


Defining a midsurface with the offset method


2. In the Midsurface dialog, choose Method→ Offset.

3. Select the solid body and click MB2 to advance to the next selection step.

4. Click Target Body and select the body.

5. Click Seed Face and select a seed face for the midsurface.

6. Set the Cliff Angle. The default is 75 degrees.



38/216

2


7. Preview the generated face to be offset by clicking the Region or FullBoundary preview buttons.

8. If necessary, adjust the Cliff Angle to ensure that the correct face is

selected. When the previewed face is correct, click OK.If Blank Original is selected, the original solid body is blanked;only the sheet body is displayed.

User Defined midsurface method

With the User Defined method, you use an existing sheet body to create amidsurface in a solid body. This method can be useful in situations wherealternate methods of midsurface creation did not produce satisfactory results.If the sheet body you create is within the confines of the solid body, thesoftware will automatically generate the midsurface, even if the body is notuniformly thick.

All faces connected to the seed face that satisfy smoothness and boundaryface criteria are offset as a midsurface half the thickness into the solid.

The software terminates midsurface creation when it encounters a boundaryface. A boundary face is defined as a face oriented in the thickness direction,

at an angle greater than or equal to the cliff angle value. The seed face willpropagate in all directions until it reaches the edge on a boundary face.

Thickness Outside Body guidelines

The user-defined midsurface can contain surfaces that extend. For example,if you have a sheet body containing small holes and you want the holes to beignored in the midsurface creation, enter a value for the Thickness OutsideBody option. This value tells the software how thick to define the "virtual"solid body when it encounters what are actually the small holes.



39/216


Note that an outside body thickness value of greater than zero isrecommended. Although it is unlikely that a zero value will cause midsurfacecreation problems, the solve could fail, especially if the midsurface extendsbeyond the solid body, because the shell thickness will be interpreted as zero.

In the following g raphic, the yellow portion of the midsurface ignores the holein the solid, while the dark green area extends beyond its boundaries. Thesoftware approximates a thickness for these regions, which you can modify.

Defining a midsurface with the user defined method


2. In the Midsurface dialog, choose Method→ User Defined.

3. Select the solid body and click MB2 to advance to the next selection step.

4. Select the sheet body.

If some part of the selected sheet body is not fully contained within thesolid body, enter a value in the Thickness Outside Body field for thesoftware to use when formatting the element thickness for a solve.

Sew

Use Sew to join together selected sheet or solid bodies.

You can use Sew to join together:



40/216

2


• Two or more sheet bodies to create a single sheet. If the collection of sheets to be sewn encloses a volume, the software creates a solid body.

• Two solid bodies if they share one or more common faces.

Creating a solid vs. sheet body

If you want to create a solid body by sewing a set of sheets together, theselected sheets must not have any gaps larger than the specified SewTolerance. Otherwise, the resulting body is a sheet, not a solid.



41/216


Sewing two solid bodies together

You can sew two solid bodies together only if they share one or more common(coincident) faces. When you use Sew, the software deletes the commonface(s) and sews the solid bodies into a single solid body.

Sew All Instances

• If a selected body is part of an instance array and you select the Sew AllInstances option, the software sews the entire instance array.

• If you deselect the Sew All Instances option, the software only sews theselected instance.

Sew Tolerance

The software sews edges together, whether there is a gap between them orwhether they overlap, if the distance between them is less than the specified

Sew Tolerance. If the distance between them is greater than this tolerance,the software cannot sew them together.



42/216

2


Subdivide Face

Subdivide Face lets you automatically subdivide multiple faces whilemaintaining associativity, using a variety of subdividing geometries. Thisfunction allows you to control a 2D mesh using global element size for aportion of the model. It is also useful if you want to subdivide a face intofour-sided regions to facilitate mapped meshing with quadrilateral elements.

The edges and faces of a subdivided face are associative and are combinedinto a group feature.

For simple edges and curves, the behavior will be as follows:



43/216


• Where a datum plane, sheet body, or face is used as a tool, the tool isintersected with the selected face to be subdivided, and the resulting curves are used for subdividing. These intersect curve features will showup in the grouped feature.

• Where the Two Points option is chosen in the filter, you can specify the endpoints of a line. The last two points selected are used to create the line.The end points are associative to the underlying geometry. The resulting line will be used to subdivide the face, projecting the line as required.

Geometry objects that are associated with the subdivided face feature cannotbe deleted.

If you transform the objects associated with a subdivided face, the face itself is also updated. If you transform the solid body on which any subdivided

faces reside, their associated curves do not move. However, the subdividedfaces are updated accordingly.

Activities

See the “Geometry idealization” activities in the Applications of Advanced Simulation Workbook.

In these acti vities, you will idealize a part.

Summary

In this lesson you:

• Learned about tools for modifying features in the idealized part, including Edit Feature Parameters, Suppress Feature, Unsuppress Feature, andMaster Model Dimension.

• Learned about tools for modifying geometry in the idealized part,including Idealize Geometry, Defeature Geometry, Partition Model,Midsurface (three methods), Sew, and Subdivide Face.



44/216

2


45/216

Lesson

3 3D meshing

Objectives

• Learn how to mesh solid bodies using 3D tetrahedral elements.

• Learn how to mesh solid bodies using 3D swept mesh elements.

• Learn how to mesh solid bodies by creating a solid mesh generated fromshell elements.

3D Tetrahedral Mesh

The 3D Tetrahedral Mesh function supports the creation of 4-noded and10-noded tetrahedral elements. You can create a 3D mesh on solid bodies forall supported solvers.



46/216

3

3D meshing

3D Mesh Options

The 3D Mesh Options dialog box defines how the meshing algorithmprocesses small features and fillets.



47/216

3D meshing

Failed elements

After meshing, the element quality is checked against the Maximum Jacobianthreshold:

• If the quality measure violates this threshold, the element is highlightedin red.

• If the quality measure is within 10% of the this threshold, the element ishighlighted in yellow.

If you have a high number of poor quality elements, you can:

• Further idealize the part’s geometry to remove problematic areas.

• Modify surface or solid mesh size variation to improve node distribution.

• Use the abstraction tools to improve the quality of the polygonal geometry.



48/216

3

3D meshing

• Increase the threshold value for Maximum Jacobian if element quality isnot critical in that area of the model.

Creating a 3D mesh

1. Click 3D Tetrahedral Mesh .

2. In the graphics window, select the solid body to mesh.

3. In the dialog, choose an element type from the drop-down list.

4. Enter an element size. Or, click to have the software

calculate an appropriate element size.

5. (Optional) Click Preview to view the resulting nodes on edges for themesh. If you are not satisfied, you can modify the Overall Element Size

value.

6. (Optional) To specify small feature tolerances and fillet processing parameters, click the Mesh Options button.

7. Click OK or Apply to generate the mesh.

3D Swept Mesh

3D Swept Mesh generates a mesh of either 8– (linear) or 20–noded(parabolic) hexahedral elements on any two-and-one-half dimensional solidby sweeping the mesh from a source face through the entire solid.

When you create a swept mesh, the software first meshes the specified sourceface of the volume with linear quadrilateral elements. The software thenpropagates that mesh into the volume layer by layer with the first layerresulting in the first set of hexahedral elements, and so on.

You can also use an existing (linear or parabolic) triangular or (linear orparabolic) quadrilateral surface mesh to generate (linear or parabolic) wedgeor (linear or parabolic) hexahedral swept mesh elements.

The mesh generation proceeds from the selected source face to the target face,which the software determines by evaluating the volume. If the initial meshoriginating from the source face contains one or more triangular elements,the swept mesh will also contain corresponding wedge elements.



49/216

3D meshing

System checks

Once you click OK or Apply on the dialog box, the software:

• Checks whether the solid is geometrically sweepable and generates anappropriate error if not.

• Checks whether the meshes on the solid’s faces or mated faces can be usedfor sweeping and generates an appropriate error if not.

• Checks whether the target face has already been meshed and generatesan error if yes.

Mesh mating conditions

For each face in the solid, the software checks to see whether mesh mating conditions on an adjacent solid are satisfied. If they are and if a mesh is

found on the face adjacent to the source face for the swept mesh, this will beused for mesh mating conditions as long as it matches the defined sweptmesh, as follows.

• For a linear or parabolic wedge swept mesh, the adjacent body must havean existing linear triangular/wedge or parabolic triangular/wedge mesh.

• For a linear or parabolic hexahedral swept mesh, the adjacent bodymust have an existing linear quadrilateral/hexahedral or parabolicquadrilateral/hexahedral mesh.



50/216

3

3D meshing

If no mesh is found on the adjacent body that satisfies other mesh mating conditions, a surface mesh is created. Free mesh or mapped mesh will bedetermined based on whether the face is a wall face. (All wall faces must bemap-meshed.) For each edge, the same logic is applied.

Generating a swept mesh from a sweepable solid

1. Click 3D Swept Mesh .

2. In the graphics window, select the sweepable solid body to mesh.

3. In the dialog, select an element type from the drop-down menu.

4. Enter an element size, or click to have the softwarecalculate an appropriate element size.

5. (Optional) Click Preview to view the resulting nodes on edges for themesh. If you are not satisfied, you can modify the Overall Element Size

value.


Generating a swept mesh from a meshed surface

1. Click 3D Swept Mesh .

2. In the graphics window, select an existing meshed surface on a sweepablesolid.

3. Select an element type from the drop-down menu.

Note that the element size is determined by the size of the seed mesh.


Solid from Shell

Use Solid From Shell to generate a solid tetrahedral mesh from atriangular shell mesh.



51/216

3D meshing

Solid meshes created from shell elements have no associativity tothe bounding shell mesh or the underlying geometry. Solid meshescreated by the Solid From Shell command are not editable. Inaddition, if any shell mesh bounding a 3D mesh created by Solid fromShell requires an update, the 3D mesh is automatically deleted. Youmust re-create the solid mesh following the shell mesh update.

To generate a solid mesh, the shell mesh must meet the following requirements:

• All 2D triangular elements must be of the same order (linear or parabolic).

Use caution when generating a solid shell from parabolicelements. Unless the parabolic triangular shell elements havestraight edges, the resulting parabolic tetrahedral mesh will

likely contain elements that fail Jacobian tests.

• The shell elements must completely enclose a volume. Otherwise, thesoftware can’t generate the solid elements.

• There are no coincident triangular elements in the shell mesh.



52/216

3

3D meshing

Use Check Nodes to identify duplicate nodes. This is a good checkfor coincident elements.

Use Element Outlines to check for element free edges. A free-edgecheck will reveal any gaps in volume boundary.

You can use the 2D Edit Mesh commands to repair any gaps in yourshell mesh.

When selected, Mesh Interior Volumes generates multiple solid meshesfrom selected shell meshes that enclose interior volumes. This is useful formodeling thermal or flow problems, in which the interior volumes wouldtypically represent a heat sink or source, or a flow obstacle.

Creating a solid mesh from shell elements

To create a solid tetrahedral mesh from triangular shell elements

1. Choose Solid from Shell .

2. Review and modify the dialog options as needed.

3. Select one or more 2D, triangular shell meshes that completely encloseone or more volumes.

4. Click OK.

Activity

See the “3D meshing” activity in the Applications of Advanced SimulationWorkbook.

In this activity, you will generate and refine a 3D mesh.

Summary

In this lesson you learned about the three 3D meshing commands:

• 3D Tetrahedral Mesh

• 3D Swept Mesh

• Solid from Shell


http://-/?-http://-/?-


53/216

Lesson

4 2D meshing

Objectives

• Learn how to generate a 2D mesh.

• Learn about tools for editing a 2D mesh.

2D meshing overview

2D Mesh generates 3- and 6-noded triangular elements as well as 4-and 8-noded quadrilateral elements. 2D elements are also commonly knownas shell or plate elements. For Tri6 and Quad8 elements, midnode snapping and a specified Jacobian ratio are supported.

The default element size does not specify the final size of the elements butdefines the parameter used to control the edge length of the element. Actual

element edge lengths are approximately equal to the specified overall elementsize.

The software automatically adjusts for problematic element sizes onrectangular or nearly rectangular surfaces (non-planar included). Theresulting element size will be "safe" and yield a higher quality mesh.



54/216

4

2D meshing

Mesh Options

The 2D Mesh Options dialog box specifies how the meshing algorithmprocesses small features and fillets.



55/216

2D meshing

Creating a 2D mesh

1. Click 2D Mesh .

2. Select the midsurface or faces you want to mesh.

In the dialog, use the Filter drop-down menu to help you select from faces,

bodies, or an existing mesh.

3. From the Type drop-down menu, choose the element type.

4. Enter a size for the Overall Element Size, or click toautomatically calculate a suggested element size.

5. If necessary, click the More Options arrow to display additional optionsfor this mesh.



56/216

4

2D meshing

6. To specify small feature tolerances and fillet processing parameters, clickthe Mesh Options button.

7. Click Preview to view the resulting nodes on edges for the mesh. If you

are not satisfied with the node number and location, you can modify theOverall Element Size value.


Editing a 2D mesh

The 2D Edit Mesh functionality provides you with a basic set of shell elementand/or node editing capabilities for the purpose of fixing elements of poor andunsatisfactory quality produced by the automatic mesh.

Edit Mesh features the following options:

Icon Label Description

Split Quad Allows you to divide quadrilateralelements (quads) into triangularelements (tris).

Splitting occurs along thesmaller of the two diagonals.

Combine Tris Allows you to combine triangular

elements (tris) into quadrilateralelements (quads).

Move Node Allows you to relocate a nodalposition.

Delete Element Allows you to delete elements of yourchoice.

Create Element Allows you to create a quad or trielement that will be added to theexisting 2D mesh. If the mesh has

higher order elements, the newlycreated element will also havemidnodes.

Unlock Mesh Allows you to unlock the edited meshfor an update operation.

Assign NodalDisplacementCoordinate System

Allows you to manually define a nodaldisplacement coordinate system forselected nodes or geometry.



57/216

2D meshing

Icon Label Description

Assign NodalDisplacement

Coordinate System

Allows you to determine thecoordinate system assigned to nodes,

or the nodes to which a coordinatesystem is assigned.

Activity

See the “2D meshing” activity in the Applications of Advanced SimulationWorkbook.

In this activity, you will generate and refine a 2D mesh.

Summary

In this lesson you:

• Learned how to generate a 2D mesh.

• Learned about tools for editing a 2D mesh.



58/216

4


59/216

Lesson

5 1D and 0D meshing

Objectives

• Learn how to create a mesh of 1D elements.

• Learn how to create weld elements.

• Learn how to create a 1D element section.

• Learn how to create a 0D mesh.

1D Mesh

1D Mesh lets you create a mesh of one-dimensional elements. You cancreate or edit one-dimensional elements, along or between points, curves,or edges.

One-dimensional elements are two-noded elements which, depending ontype, may or may not require an orientation component. A one-dimensionalelement is one in which the properties of the element are defined along a lineor curve. Typical applications for the 1D element include beams, stiffeners,and truss structures.



60/216

5

1D and 0D meshing

1D element meshing methods

The following section describes methods available for creating different typesof 1D mesh. These methods are based on the way you select geometry using Selection Step icons in the 1D Mesh dialog.

Ordered Nodes method

Using this method (which requires selection of a point or points for Group 1 aswell as Group 2), two ordered sets of point locations are created. These pointlocations are associated to the parent data from which they were selected.



61/216

1D and 0D meshing

Depending on the quantity of data selected for this method, several outputsare possible:

• If the number of points created in each set (Group 1 and Group 2)

are equal, then a single 1D element is generated between each set of corresponding points, as shown in the graphic above.

• If the number of points created in each set are unequal, then 1D elementsare created from all of the points in Group 1 to all points in Group 2.This option provides a "one to many" type of connection, as shown in thefollowing figure.

Point-to-Point Chaining method

This method, which requires Group 1 selection only, generates a chain of 1Delements between the points that you select. The elements that are createdform a consecutive link between the successive point locations.



62/216

5

1D and 0D meshing

Along a Curve (Edge) method

This method, which requires Group 1 selection only, generates a series of 1Delements along single or multiple curves or edges. You can specify a totalnumber of elements or an element size for the elements. Nodes created atcoincident point locations on adjacent curves/edges are shared.

Point-to-Curve (Edge) method

For this method, which requires selection of a Group 1 point and a Group 2curve, elements are created similarly to the Ordered Nodes method. In thePoint-to-Curve method, however, the curve you select for Group 2 infers thesecond curve set, as shown in the following figure.

Curve-to-Curve method

This method, which requires selection of a curve for both Group 1 andGroup 2, generates 1D elements between two curves or edges. The point



63/216

1D and 0D meshing

locations associated to the parent curve/edge will be used to determine thecorresponding node locations.

If the two sets of point locations do not contain the same number of points,the software matches all possible points and build the rest of the elementsbetween a point on one curve and the remaining points on the other curve.

Creating a 1D mesh

1. Click (1D Mesh).

2. In the dialog, choose an element type.

3. Choose either Default Element Number or Size and enter a value:

• If you select Number , enter an element density. If you enter 9 forexample, and select an edge, the software will distribute nine elements

along the selected edge.

• If you select Size, enter a size in model units.

4. (Optional) Select Create Mesh Points to create selectable mesh points onor relative to CAE geometry. For example, you could create a mesh pointat an arc centerpoint to create a spider mesh at a large hole. Or you couldcreate mesh points to force a node location on an edge or improve nodedistribution on a curve.

5. Use the Selection Steps (Group 1, Group 2) to define sections.

6. Choose Apply or OK. 1D elements are built along or between the objectsyou selected for meshing.

Create Weld Elements

Create Weld Elements allows you to model welds by projecting a set of pointsto top faces and using the resulting points to project to bottom faces, using the Normal to Face option in both projections.



64/216

5

1D and 0D meshing

Weld mesh effect on 1D mesh

When you exit the Create Weld Elements dialog box, the ordered set of points

from the top faces will be added to Group 1 selection step of the 1D Meshdialog, and the ordered set of points from the bottom faces will be added toGroup 2. You can then create any type of 1D element available. In addition,the software honors the weld elements during 2D face meshing.

Support for interior hard curves in meshing

This feature gives you the ability to associate curves to faces to representweld locations in the Create Weld Elements dialog. These weld points aretreated as interior hard curves. The point locations on the hard curves arehonored by the software during 2D meshing.

Creating a weld element mesh

1. Click 1D Mesh .

2. Choose an element type.

3. Choose either Default Element Number or Size and enter a value:

• If you select Number , enter an element density. If you enter 9 forexample, and select an edge, the software will distribute nine elements

along the selected edge.

• If you select Size, enter a size in model units.

4. Click Create Weld Elements.

The Create Weld Elements dialog is displayed.

5. Using the Points/Curves selection step, select points, curves, or edges. Usethe Filter menu to pinpoint selection. Click OK to confirm the selection.



65/216

1D and 0D meshing

6. Use the Top Faces selection step to project the points, curves, or edges.Click OK to confirm the selection.

7. Use the Bottom Faces selection step to choose the bottom face and click

OK to confirm the selection. Temporary points are displayed at theprojected locations.

8. Click OK or Apply to return to the 1D Mesh dialog. The Top Facesselection is added to Group 1 and the Bottom Faces selection is addedto Group 2.

9. Click OK or Apply to project the points and create weld elements. Theelements are created between each pair of points (the point on the top faceand the corresponding point on the bottom face).

1D Element Section

1D Element Section helps you create sections, which you canthen assign and analyze for comparison to a bar or beam element mesh,curves/edges, or points, and display the results.

This feature also lets you create associative section properties from theanalysis, which can then be used for beam model analysis. Since sectionproperties are associative, they are updated whenever changes are made to

the data from which they are derived.



66/216

Documents

UGS NX 4 ADVANCED SIMULATION.pdf