Welcome to the WWW home page for FElt. FElt is an open source system for finite element analysis; this document provides an overview of the features in that system.

  • General overview of the FElt system components.
  • Example problems that demonstrate what kinds of problems FElt can solve, how FElt can help you set them up, and what kinds of output and post-processing options are available.
  • Traditional documentation for FElt, including a FAQ, READMEs, man pages, and our comprehensive User's Guide.
  • The SourceForge project page gives you access to the project administration (mailing lists, file releases, etc.).
  • File releases on SourceForce is usually the fastest way to download the latest versions.
  • Or check the archives if you want to download older versions or binaries that haven't been posted as a file release.

General Overview

The current version of FElt knows how to solve linear static and dynamic structural and thermal analysis problems; it can also do modal and spectral analysis for dynamic problems. FElt's element library currently contains fourteen elements. The FAQ contains some additional information about what what kinds of problems FElt can solve as well as some information about expandability if you think you'd like to hack on FElt for your own purposes. A user can access FElt's capabilities through several different interfaces. The three most important are felt, the basic command-line application for solving FE problems given a standard FElt input file, burlap, our powerful, interactive, scripting environment that combines the flexibility of Matlab-like programs with FElt's finite element know-how and velvet, the full-featured CAD like pre- and post-processor that uses the X Window System for a graphical environment. All three applications use an intuitive, ASCII based syntax for problem definition. This powerful syntax allows you to substitute analytic functions in place of numeric values (sin(60) instead of 0.866025) and even more importantly allows for time-dependent forcing and boundary conditions to be specified as analytic functions of time or in the more traditional fashion as a series of discrete time, magnitude pairs. This feature makes it quite easy to specify a wide range of functions.

While felt, velvet and burlap all read and write this powerful syntax, velvet is basically designed such that you would never actually have to see the internals of one of these files because it lets you define your problem graphically. This is particularly useful for more complicated geometries like the one in our wrench example.

Velvet also allows for much more powerful post-processing than the simple text output that felt offers. We can generate a color plot of stress contours for the above wrench problem with one simple menu selection after we have solved the problem in velvet. Displacement contours, and two- and three-dimensional wire frame plots of the displaced shape are also available post-processing options in velvet. For hardcopy rendering, the color contour plots can be saved in PPM or EPS format and the wire frame plots as PostScript documents. For transient analysis problems, velvet replaces felt's ASCII based time-displacement plots with a graphical version that can be saved as a PostScript file. Velvet can also do animations of transient structural analysis problems and plot the mode shapes in a modal analysis problem.

Other applications in FElt include corduroy, patchwork, and yardstick. corduroy is a command-line application that gives you command-line access to FElt's mesh generation capabilities (which are also available in velvet). corduroy has its own intuitive, easy to use input syntax. The equivalent corduroy input file for the wrench example is shown here. Patchwork is an application for input file format conversion (to convert between FElt and DXF files for example) and yardstick is a simple application for problem scaling and unit conversion.

For Windows environments (95, 98, NT, etc.) there is an editor/encapsulator available. WinFElt gives you a GUI interface to the command line applications and has some post-processing capabilities. It is not a graphical pre-processor like velvet.

For people who want to use FElt on a DOS platform, a ZIP distribution of the command-line applications (felt, burlap, corduroy, patchwork, and yardstick) is available. The DOS distribution of FElt also includes feltvu, a simple graphical previewer for FElt problems. The DOS versions of FElt will only run on a 386 or better. Note that these versions are no longer maintained.

Finally, because this is a Web page we might as well include the obligatory links to some other interesting places. Here are some for other packages useful in finite element analysis and numerical analysis in general (we'd be happy to accept additional suggestions for this list - I know that some of the major commercial FE vendors must have Web pages):

For more information, please do take a look at the other documentation that exists for FElt. If you still have questions then please feel free to drop one of us a note at:

datkinson@clarku.edu or jgobat@sourceforge.net (Last updated 22-Feb-00)