FElt: User’s Guide and Reference Manual Jason I. Gobat Applied Physics Laboratory University of Washington Darren C. Atkinson Department of Computer Engineering Santa Clara University Computer Science Technical Report CS94-376 University of California, San Diego Legal Notice Copyright c 1993 – 2005 Jason Gobat and Darren Atkinson [email protected] and [email protected] “The FElt System: User’s Guide and Reference Manual” may be reproduced and distributed in whole or in part, subject to the following conditions: 0. The copyright notice above and this permission notice must be preserved complete on all complete or partial copies. 1. Any translation or derivative work of “The FElt System: User’s Guide and Reference Man- ual” must be approved by the authors in writing before distribution. 2. If you distribute “The FElt System: User’s Guide and Reference Manual” in part, instruc- tions for obtaining the complete version of “The FElt System: User’s Guide and Reference Manual” must be included, and a means for obtaining a complete version provided. 3. Small portions may be reproduced as illustrations for reviews or quotes in other works without this permission notice if proper citation is given. 4. The GNU General Public License referenced below may be reproduced under the condi- tions given within it. All source code in the FElt system is placed under the GNU General Public License. See ap- pendix B for a copy of the GNU “GPL.” The authors are not liable for any damages, direct or indirect, resulting from the use of information provided in this document. Contents Foreword xvii About this Manual ................................. xvii Organization of this Manual ............................ xvii Typographical Conventions ............................. xviii Acknowledgements ................................. xix 1 Introduction to the FElt System 1 1.1 Intentions ................................... 1 1.2 FElt: What it can do for you ......................... 2 1.3 FElt: What it cannot do for you ........................ 3 2 FElt Analysis Types 5 2.1 Introduction .................................. 5 2.2 Static structural analysis ........................... 5 2.3 Transient structural analysis ......................... 7 2.4 Static thermal analysis ............................ 8 2.5 Transient thermal analysis .......................... 8 2.6 Modal analysis ................................ 8 2.7 Spectral analysis ............................... 10 2.8 Nonlinear static analysis ........................... 11 2.9 Nonlinear dynamic analysis .......................... 11 iii iv CONTENTS 3 Structure of a FElt Problem 13 3.1 Input file syntax ................................ 13 3.1.1 General rules ............................. 13 3.1.2 Expressions .............................. 14 3.1.2.1 Continuous functions ................... 14 3.1.2.2 Discrete functions ..................... 14 3.1.3 Units ................................. 16 3.1.4 A simple example .......................... 16 3.2 Sections of a FElt input file .......................... 17 3.2.1 Problem description ......................... 17 3.2.2 Nodes ................................. 17 3.2.3 Elements ............................... 18 3.2.4 Material properties .......................... 18 3.2.5 Constraints .............................. 19 3.2.6 Forces ................................. 20 3.2.7 Distributed loads ........................... 21 3.2.8 Analysis parameters ......................... 22 3.2.9 Load cases .............................. 22 3.3 An illustrated example ............................ 22 3.4 An example of a transient analysis problem ................. 25 3.5 Format conversion .............................. 27 3.5.1 Conversion basics .......................... 27 3.5.2 patchwork details ........................... 28 4 The FElt Element Library 29 4.1 Introduction .................................. 29 4.2 Structural analysis elements ......................... 30 4.2.1 Truss and spring elements ...................... 30 CONTENTS v 4.2.2 Euler-Bernoulli beam elements .................... 31 4.2.2.1 Special case two-dimensional element .......... 31 4.2.2.2 Arbitrarily oriented three-dimensional element ...... 34 4.2.3 Timoshenko beam element ...................... 34 4.2.4 Constant Strain Triangular (CST) elements ............. 35 4.2.5 Two-dimensional isoparametric elements .............. 36 4.2.5.1 General four to nine node element ............ 36 4.2.5.2 Simple four node element ................. 37 4.2.6 Plate bending element ........................ 37 4.2.7 Solid brick element .......................... 39 4.2.8 Axisymmetric elements ....................... 40 4.3 Thermal analysis elements .......................... 40 4.3.1 Rod element ............................. 40 4.3.2 Constant Temperature Gradient (CTG) element ........... 40 5 The felt Application 41 5.1 Using felt ................................... 41 5.2 Solving a problem ............................... 44 5.3 Interpreting the output from felt ....................... 44 5.3.1 Static analysis ............................ 44 5.3.2 Transient analysis ........................... 47 5.3.3 Modal analysis ............................ 49 5.3.4 Thermal analysis ........................... 51 5.3.5 Spectral analysis ........................... 51 6 Using WinFElt 53 6.1 Introduction to WinFElt ............................ 53 6.2 Solving a problem ............................... 53 6.3 Text output .................................. 56 vi CONTENTS 6.4 Graphical output ............................... 56 6.4.1 Contour plots ............................. 56 6.4.2 Line graphs .............................. 56 6.4.3 Wireframe drawings ......................... 56 7 The velvet Application 61 7.1 Introduction to the velvet GUI ........................ 61 7.2 General features of the interface ....................... 61 7.3 Working with files ............................... 63 7.4 Configuring the drawing area ......................... 65 7.4.1 Basic controls ............................. 65 7.4.2 Object coloring ............................ 66 7.4.3 Zooming ............................... 67 7.4.4 Dumping the drawing area ...................... 68 7.5 Drawing and defining a problem ....................... 68 7.5.1 Defining attributable objects ..................... 69 7.5.1.1 The material dialog .................... 71 7.5.1.2 The constraint dialog ................... 71 7.5.1.3 The force dialog ...................... 72 7.5.1.4 The load dialog ...................... 72 7.5.2 Working with nodes and elements .................. 73 7.6 More on nodes and elements ......................... 75 7.6.1 Editing nodes ............................. 75 7.6.2 Automatic node renumbering .................... 76 7.6.3 Editing elements ........................... 77 7.7 Using tools .................................. 78 7.8 Material databases and defaults files ..................... 80 7.9 Automated element generation ........................ 81 CONTENTS vii 7.9.1 Generating a grid of line or quadrilateral elements ......... 81 7.9.2 Generating a mesh of triangular elements .............. 81 7.10 Keyboard interface mechanisms ....................... 82 7.10.1 Keyboard shortcuts .......................... 82 7.10.2 Command names ........................... 83 7.11 Command line options ............................ 85 8 Post-processing with velvet 87 8.1 Solving a problem with velvet ........................ 87 8.2 Problem description and analysis parameters ................. 92 8.3 Controlling the post-processing ........................ 92 8.3.1 Controlling contour plots ....................... 92 8.3.2 Controlling structure plots ...................... 94 8.3.3 Controlling animation ........................ 94 9 The corduroy Application 97 9.1 Introduction .................................. 97 9.2 The corduroy syntax ............................. 97 9.2.1 Specifying basic parameters ..................... 97 9.2.2 Generating elements along a line ................... 98 9.2.3 Generating a grid of line elements .................. 98 9.2.4 Generating a grid of quadrilateral planar elements .......... 99 9.2.5 Generating a grid of solid brick elements .............. 99 9.2.6 Grid spacing rules .......................... 99 9.2.7 Generating a triangular mesh ..................... 100 9.3 Using corduroy ................................ 102 9.4 Incorporating output into a FElt file ..................... 102 viii CONTENTS 10 The burlap Application 105 10.1 Introduction to the burlap environment .................... 105 10.2 Using burlap ................................. 105 10.2.1 Interacting with burlap ........................ 105 10.3 burlap and FElt ................................ 108 10.3.1 Element objects ............................ 109 10.3.2 Node objects ............................. 109 10.3.3 Material objects ............................ 110 10.3.4 Force objects ............................. 110 10.3.5 Constraint objects .......................... 111 10.3.6 Distributed load objects ....................... 111 10.3.7 Element definition objects ...................... 113 10.3.8 Problem definition .......................... 113 10.3.9 Analysis parameters ......................... 116 10.4 Adding new element types to burlap ..................... 116 10.5 Tips on using interactive mode ........................ 119 10.6 Common error messages ........................... 121 11 The burlap Syntax 123 11.1 Literals ...................................