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Pro MECHANICA STRUCTUREWILDFIRE 4

ELEMENTS AND APPLICATIONS Part I

Yves Gagnon, M.A.Sc.Finite Element Analyst & Structural Consultant

SDCSchroff Development Corporation

www.schroff.com

PUBLICATIONS

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Table of Contents

Preface iAcknowledgements iAbout the Author iiFiles for this Manual iiTable of Contents iiiIntroduction vii

Introduction to Mechanica Functionality 1Key Assumptions in FEA 1

Geometry 1Material Properties 1Mesh 2Boundary Conditions 2

Elements Used in FEA 3Review of Element Behavior and Geometric Classifications 3Common Modeling and Element Types 3Planar Simulation Modeling 4

Plane Stress 4Plane Strain 5Axisymmetric 5

Three Dimensional Simulation 5Beam Elements 6Shell Elements 6Axisymmetric Modeling 7Planar Symmetry 7

Solid Modeling 7Special Elements 8

Spring Elements 8Mass Elements 9

Basic Elements for the FEA Beginner 9Useful FEA Terminology 11Shape Function 12

H vs P Elements 12

Introduction Exercise

Mechanica Functionality in Integrated Mode 13 Introduction 13Mechanica Tools and Terminology 13

System of Units 13World Coordinate System 15Measures 15

Typical Finite Element Procedure 173-D Idealizations 17

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Materials 18Finite Element Mesh 20Boundary Conditions 21Analyses 23Results 24

Mechanica Files 26Exercise 1

Beam Elements 31Objectives 31Introduction 31Procedure 32

Start Pro/ENGINEER WILDFIRE 33Create a part named: beam 33Setting up in Pro/ENGINEER WILDFIRE for FEA Modeling 35

Creating a datum curve for beam assignment 35Procedure in Pro/MECHANICA 36

Go to Pro/MECHANICA from Pro/ENGINEER 36Beam Assignment 37

Beam Section 37Beam Orientation 39Beam Definition 40

Constraints 42Loads 44Generating Beam Elements 46Set up and Run Analysis 47

Static Analysis 47Running the Analysis 48

Analysis of Results 50Approximate Finite Element Analysis Solution (Theory Warning) 53Conclusion 59Project 1 60References 62

Exercise 2

Shell Elements Using a Plane Stress Model 63Introduction 63Overview 63Exact Solution 64Procedure in Pro/MECHANICA 66

Shell Properties 67Generating Elements 68Loads and Constraints 70Creating the Analyses 76Running Analyses 78Results 80

Project 2 87

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Exercise 3

Shell Elements Using Mid-Surface Compression 89Objectives 89Introduction 89Procedure 91

Start Pro/ENGINEER WILDFIRE 93Open the Part Named: x_mbr 93Open the Part Named: cab_skin.prt 96Open the Assembly cab.asm 98Boundary Conditions 99

Constraints 99Loads 100

Assign Materials 103The Mesh Myth Demystified 105Creating the Mesh 108Set up and Run Analysis 110

Notes on Debugging a Failed Mesh 113A few more notes on Automeshing (AutoGEM) versusManual Meshing 113

Notes on Convergence 114Uncertainty 114The Error Estimate 115Convergence 115How to determine the correct convergence level inPro/MECHANICA 117Convergence Types in Pro/MECHANICA 118

Results 120Conclusion 125Project 3 126References 128

Exercise 4

Boundary Conditions Regions 129Objectives 129Introduction 129Overview 130Procedure 131

Start Pro/ENGINEER WILDFIRE 131Open part: plate_regions.prt 131Creating Regions 132Shell Element Creation 132Assign Materials 133Boundary Conditions 135

Constraints 135Loads 136

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Meshing of the FEA Model 137Set up and Run Analysis 139

Static Analysis 139Results of Static Analysis 141

Conclusion 145

Project 4 145Exercise 5

Mass and Spring Elements in Dynamic Motion 149Objectives 149Introduction 149

Modal (or Natural Frequency) Analysis 149Dynamic Analysis 151

General 151Frequency Response Analysis 151

Transient Response Analysis 153

Dynamic Time Analysis 154Random Response Analysis 154Modal Analysis ExerciseUsing Pro/MECHANICA in Integrated Mode 155

Introduction 155Objectives 155Overview of Exercise 155Procedure 156

Setting Up the Model and the FEA Modeling 156Pro/MECHANICA Procedure 157

Shell Creation 157Part Materials 158

Setting Up User-Defined Measures 161Mass Simulation 163Spring Elements 166

Assign Boundary Conditions to the Model 171Loads 171Constraints 172

Creating the Dynamic Analyses (constrained) 173Dynamic Analysis 174Run the Analysis Dynamic_1 179

Frequency Results 180Modal Analysis 180Dynamic Frequency Analysis Results 183Output Measures 183

Conclusion 186Project 5 187

Conclusions 191