prev

next

out of 267

Published on

15-Nov-2014View

111Download

6

DESCRIPTION

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

s

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

s

s s

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

s s s s

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

s

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

s

Main Index

s

- 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

s

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

s s

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

s

s

Main Index

s

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

s s

s s

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

s s

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

s

Main Index

s s s s s s s

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

s

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.Nastran Results, 201 - The .f06 Results File, 201 - Stress Results, 207

s

s

Main Index

14Overview of Other MSC.Nastran Capabilitiess

Techniques for Analyzing Large Models, 210 Efficient Solution of Large Matrix Problems, 210 Superelement Analysis, 210 Axisymmetric Analysis, 211 Cyclic Symmetry Analysis, 212 Dynamic Analysis, 213 Normal Modes Analysis, 213 Frequency Response Analysis, 213 Transient Response Analysis, 214 Complex Eigenanalysis, 215 Response Spectrum Analysis, 216 Component Mode Synthesis, 216 Random Vibration Analysis, 216 Nonlinear Analysis, 217 Geometric Nonlinearity, 217 Material Nonlinearity, 217 Nonlinear Transient Analysis, 218 Design Sensitivity and Optimization, 219 Overview, 219 MSC.Nastran Capabilities, 219 Application Examples, 220 Aeroelasticity, 222 Static Aeroelastic Response, 222 Aerodynamic Flutter, 222 Dynamic Aeroelastic Response, 223 Aerodynamic Methods, 223 Thermal Analysis, 224 Composite Materials, 225 Fluid-Structure Interaction, 226

s

s

s

s

s s s

Main Index

ASummary of Basic Case Control Commands

BSummary of Basic Bulk Data Entries

Bibliography

Glossary

Main Index

Main Index

Getting Started with MSC.Nastran Users Guide

Preface

s About this Book s List of MSC.Nastran Books s Technical Support s Internet Resources s Permission to Copy and Distribute MSC Documentation

Main Index

ii

About this BookHow to Use this GuideMSC.Nastran is a powerful general purpose finite element program that provides an extraordinary range of time-tested analysis capabilities. Problems that were intractable even a few years ago are routinely solved today using this technology. Prerequisites. This book written exclusively for the new MSC.Nastran user. No prior experience with commercial finite element software is assumed and no finite element-specific university coursework is required. It is assumed that you have a bachelors degree in any of the fields relevant to structural analysis: mechanical engineering, civil engineering, engineering mechanics, or the equivalent. Goals of this Book. The principal goal of this book is to give new users the ability to model the basic types of beam, plate, and solid structures described in typical undergraduate mechanics-of-materials classes. 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. Part I. This book is self-contained and designed to be read from beginning to end-many topics are introduced in general terms and expanded upon in subsequent discussions when the need for added detail arises. Part I of this book contains a broad overview of the finite element method, the MSC.Nastran program, and the makeup of an MSC.Nastran finite element model. Part II. Part II describes the basic design, construction, and execution of MSC.Nastran models. Basic Modeling Issues (p. 7) describes several important elementary modeling concepts and MSC.Nastran issues. Specifying the Type of Analysis (p. 7) through Additional Considerations (p. 7) describe in detail the various components of an MSC.Nastran model and are organized the way engineers think about a structural problem (i.e., the type of analysis, geometry, boundary conditions, materials, loads, and so on). Performing an MSC.Nastran Analysis Step-by-Step (p. 7) contains a complete and fully narrated description of a simple MSC.Nastran analysis. Part III. In Part III, Example Problems (p. 7) provides several additional example problems for further review and practice, and Overview of Other MSC.Nastran Capabilities (p. 7) gives an overview of MSC.Nastrans wide-ranging intermediate and advanced capabilities. The Second Edition of the this book has been updated to correspond with MSC.Nastran Version 69.

Main Index

Preface

x

Note to the ReaderThis guide contains many excerpts from another MSC Software book, the MSC.Nastran Quick Reference Guide. The MSC.Nastran Quick Reference Guide contains complete descriptions of all the finite element input data and options available in MSC.Nastran. Most of the excerpts have been edited-some extensively-to eliminate material that is not relevant to the topics covered in this book. After reading Getting Started, we recommend that you review the complete descriptions in the Quick Reference Guide in order to gain a broader understanding of MSC.Nastrans features and capabilities.

Main Index

v

List of MSC.Nastran BooksBelow is a list of some of the MSC.Nastran documents. You may order any of these documents from the MSC.Software BooksMart site at www.engineering-e.com.

Installation and Release Guides Installation and Operations Guide Release Guide

Reference Books Quick Reference Guide DMAP Programmers Guide Reference Manual

Users Guides Getting Started Linear Static Analysis Basic Dynamic Analysis Advanced Dynamic Analysis Design Sensitivity and Optimization Therm...