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This goal of this manual is to give new users the ability to model basic types of beam, plate, and solid structures. Concentrating on linear static analysis, we will learn how to design an MSC.Nastran model, define its geometry, choose finite elements based on our knowledge of the mechanical behavior of the structure, define boundary conditions, apply loads, request and control program output, and interpret the results of an analysis. In addition, we will gain a basic understanding of some of MSC.Nastrans most popular intermediate and advanced analysis features.

Transcript

MSC.Nastran 2001Getting Started with MSC.Nastran Users Guide

Main Index

Corporate MSC.Software Corporation 2 MacArthur Place Santa Ana, CA 92707 USA Telephone: (800) 345-2078 Fax: (714) 784-4056 Europe MSC.Software GmbH Am Moosfeld 13 81829 Munich, Germany Telephone: (49) (89) 43 19 87 0 Fax: (49) (89) 43 61 71 6 Asia Pacific MSC.Software Japan Ltd. Shinjuku First West 8F 23-7 Nishi Shinjuku 1-Chome, Shinjyku-Ku, Tokyo 160-0023, Japan Telephone: (81) (03) 6911 1200 Fax: (81) (03) 6911 1201 Worldwide Web www.mscsoftware.com DisclaimerThis documentation, as well as the software described in it, is furnished under license and may be used only in accordance with the terms of such license. MSC.Software Corporation reserves the right to make changes in specifications and other information contained in this document without prior notice. The concepts, methods, and examples presented in this text are for illustrative and educational purposes only, and are not intended to be exhaustive or to apply to any particular engineering problem or design. MSC.Software Corporation assumes no liability or responsibility to any person or company for direct or indirect damages resulting from the use of any information contained herein. User Documentation: Copyright 2004 MSC.Software Corporation. Printed in U.S.A. All Rights Reserved. This notice shall be marked on any reproduction of this documentation, in whole or in part. Any reproduction or distribution of this document, in whole or in part, without the prior written consent of MSC.Software Corporation is prohibited. The software described herein may contain certain third-party software that is protected by copyright and licensed from MSC.Software suppliers. MSC, MSC/, MSC., MSC.Dytran, MSC.Fatigue, MSC.Marc, MSC.Patran, MSC.Patran Analysis Manager, MSC.Patran CATXPRES, MSC.Patran FEA, MSC.Patran Laminate Modeler, MSC.Patran Materials, MSC.Patran Thermal, MSC.Patran Queue Manager and PATRAN are trademarks or registered trademarks of MSC.Software Corporation in the United States and/or other countries. NASTRAN is a registered trademark of NASA. PAM-CRASH is a trademark or registered trademark of ESI Group. SAMCEF is a trademark or registered trademark of Samtech SA. LS-DYNA is a trademark or registered trademark of Livermore Software Technology Corporation. ANSYS is a registered trademark of SAS IP, Inc., a wholly owned subsidiary of ANSYS Inc. ABAQUS is a registered trademark of ABAQUS Inc. ACIS is a registered trademark of Spatial Technology, Inc. CATIA is a registered trademark of Dassault Systemes, SA. EUCLID is a registered trademark of Matra Datavision Corporation. FLEXlm is a registered trademark of GLOBEtrotter Software, Inc. HPGL is a trademark of Hewlett Packard. PostScript is a registered trademark of Adobe Systems, Inc. PTC, CADDS and Pro/ENGINEER are trademarks or registered trademarks of Parametric Technology Corporation or its subsidiaries in the United States and/or other countries.Unigraphics, Parasolid and I-DEAS are registered trademarks of Electronic Data Systems Corporation or its subsidiaries in the United States and/or other countries. All other brand names, product names or trademarks belong to their respective owners.

Main Index

C O N T E N T SGetting Started with MSC.Nastran Users GuideGetting Started with MSC.Nastran Users Guide

Preface

s s s s s

About this Book, xii List of MSC.Nastran Books, xiv Technical Support, xv www.mscsoftware.com, xvii Permission to Copy and Distribute MSC Documentation, xix

1Some Preliminariess s s

The Role of the Finite Element Method in Engineering Analysis, 2 The Finite Element Process, 4 The Basic Matrix Equation of Linear Static Analysis, 5 The Elemental Stiffness Matrix, 5 The Global Stiffness Matrix, 7 Solution Flowchart, 10 Assumptions and Limitations of Linear Static Analysis, 11

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2Overview of the MSC.Nastran Finite Element Models s

MSC.NastranWhat Is It?, 14 Describing the Structure, 15 Coordinate Systems, 15 Model Geometry, 16 Finite Elements, 17 Loads, 18 Boundary Conditions, 18 Material Properties, 19 The Structure of the MSC.Nastran Input File, 20 - NASTRAN Statement (optional), 21 - File Management Section (optional), 22 - Executive Control Section (required), 22 - Case Control Section (required), 22 - Bulk Data Section (required), 22 A Simple MSC.Nastran Model, 23 Files Created by MSC.Nastran, 27

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Main Index

3Basic Modeling Issuess s

Units, 30 Format of the Input Data, 31 Real, Integer, and Character Input Data, 31 Free, Small, and Large Field Formats, 31 - Free Field Format, 32 - Small Field Format, 33 - Large Field Format, 33 Continuations, 34 Meshes and Mesh Transitions, 36 Designing the Model, 37 Using Test Models, 39 Pre- and Postprocessors, 40

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4Specifying the Type of Analysiss

Executive Control Section, 42 - The ID Statement, 42 - The SOL Statement, 42 - The TIME Statement, 42 - The CEND Statement, 42 Solution Sequences, 44

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5Model Geometrys s

Grid Points, 46 Coordinate Systems, 48 The Basic Coordinate System, 48 Local Coordinate Systems, 48

6The Basic Element Librarys s s

Introduction, 54 Spring Element (CELAS2), 55 Line Elements, 58 Rod Element (CONROD), 58 Rod Element (CROD), 60 Rod Element Property (PROD), 60 Simple Beam Element (CBAR), 61 - CBAR Element Characteristics, 61 - CBAR Format, 61 - CBAR Element Coordinate System, 63 - CBAR Force and Moment Conventions, 65 - Bar Element Property (PBAR), 67 Surface Elements, 69 Quadrilateral Plate Element (CQUAD4), 69

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Main Index

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- CQUAD4 Format, 70 - CQUAD4 Element Coordinate System, 70 - CQUAD4 Force and Moment Conventions, 71 Triangular Plate Element (CTRIA3), 72 - CTRIA3 Format, 72 - CTRIA3 Element Coordinate System, 73 Shell Element Property (PSHELL), 73 Other Surface Elements, 79

Solid Elements, 81 Six-Sided Solid Element (CHEXA), 81 - CHEXA Format, 81 Five-Sided Solid Element (CPENTA), 83 - CPENTA Format, 83 Four-Sided Solid Element (CTETRA), 84 - CTETRA Format, 85 Solid Element Property (PSOLID), 86 Rigid Bar Element (RBE2), 88

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7Applying Constraintss s s

Introduction, 92 Rigid Body Motion and Mechanisms, 93 Single Point Constraints, 94 Permanent Constraint on the GRID Entry, 94 Single Point Constraint (SPC), 94 Single Point Constraint (SPC1), 95 Automatic Identification and Removal of Singularities (AUTOSPC), 96 Boundary Condition Examples, 97 Example 1 Cantilever Beam, 97 Example 2 Fixed Plate, 97 Example 3 Fixed-Hinged Beam, 98

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8Material Propertiess s s

Basic Material Property Definitions, 102 Material Definition (MAT1), 104 Other Material Types Available in MSC.Nastran, 106

9Applying Static Loadss

Introduction, 108 Overview of Basic Static Loads, 108 - Load Sets, 111 Concentrated Loads, 112 Forces (FORCE), 112 Moments (MOMENT), 113 Distributed Load on a 1-D Element (PLOAD1), 115

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Main Index

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Pressure Loads, 119 Uniform Normal Pressure Load on a Triangular or Quadrilateral Surface (PLOAD), 119 Uniform Normal Pressure Load on a 2-D Element (PLOAD2), 119 Normal or Traction Pressure Load on the Face of a 2-D or 3-D Element (PLOAD4), 120 Acceleration Loads (GRAV), 123 Enforced Displacements, 126 Static Element Deformation (DEFORM), 126 Enforced Displacement Value (SPCD), 126 Combining Loads (LOAD), 127 Using Subcases (SUBCASE, SUBCOM, SUBSEQ), 129 - In SUBCOM 10:, 130 - In SUBCOM 20:, 130

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10Controlling the Analysis Outputs s s s

Printing the Input File (ECHO), 132 Output Titles (TITLE, SUBTITLE, LABEL), 135 Case Control Sets (SET), 136 Requesting Analysis Results, 137 Grid Point Output (DISP, SPCF, OLOAD, GPFORCE), 137 Element Output (STRESS, FORCE, STRAIN, ESE), 138

11Additional Considerationss s s

MSC.Nastran User and System Messages, 140 EpsilonA Measure of Numerical Behavior, 142 Element Distortion and Accuracy, 143 CQUAD4 Plate Element Distortion, 143 CHEXA Solid Element Distortion, 144 The Current Error List, 145 The Comment ($) Entry, 148

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12Performing an MSC.Nastran Analysis Step-bySteps s s s

Defining the Problem, 150 Specifying the Type of Analysis, 151 Designing the Model, 152 Creating the Model Geometry, 153 Coordinate System, 153 GRID Points, 153 Defining the Finite Elements, 155 The CBAR Entry, 155 The PBAR Entry, 156

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Main Index

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Representing Boundary Conditions, 159 Specifying Material Properties, 161 Applying the Loads, 162 Controlling the Analysis Output, 163 Completing the Input File and Running the Model, 164 MSC.Nastran Output, 166 Reviewing the Results, 170 Check for Error Messages, Epsilon, and Reasonable Displacements, 170 Check Reactions, 171 Check Shear Along the Beam, 171 Displacement and Stress Results, 172 Comparing the Results with Theory, 175

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13Example Problemss

Cantilever Beam with a Distributed Load and a Concentrated Moment, 178 Problem Statement, 178 The Finite Element Model, 178 - Applying the Loads, 178 - Applying the Constraints, 179 - Output Requests, 179 - The Input File, 179 MSC.Nastran Results, 180 - The .f06 Results File, 180 - Reviewing the Results, 183 Comparison with Theory, 184 Rectangular Plate (fixed-hinged-hinged-free) with a Uniform Lateral Pressure Load, 186 - Problem Statement, 186 The Finite Element Model, 186 - Designing the Model, 186 - Applying the Load, 187 - Applying the Constraints, 187 - Output Requests, 189 - The Input File, 189 MSC.Nastran Results, 191 - The .f06 Results File, 191 - Comparison with Theory, 196 Gear Tooth with Solid Elements, 197 - Problem Statement, 197 - The Finite Element Model, 197 MSC.Nast