This is the list of frequently asked questions for FElt

last modified: 11-18-97
  1. What is FElt?
  2. Where can I get FElt?
  3. What machines does FElt run on?
  4. I think I found a bug, what now?
  5. Is there a newsgroup or mailing list for FElt?
  6. Why do the FElt components have such stupid names?

  1. What is FElt?
  2. FElt is a free system for introductory level finite element analysis. It is primarily intended as a teaching tool for introductory type courses in finite elements - probably in the mechanical/structural/civil fields. In a command line environment, FElt uses an intuitive, straightforward input syntax to describe problems. It also includes a graphical user interface for workstations that allows the user to set-up, solve and post-process the problem in a single CAD-like environment.

    From the end-user point of view, FElt consists of six programs: felt, burlap, velvet, corduroy, patchwork, and yardstick. felt is the basic command-line application; burlap is an interactive Matlab-like environment for scripting your own elements and analyses; velvet is the primary GUI interface into the bulk of the functionality in FElt; corduroy is command-line program for automatic element generation; patchwork is a command-line application for file format conversion to and from the FElt syntax; and yardstick is a simple program for problem scaling and unit conversion.

    Felt is the simplest - it takes a FElt input file and spits back appropriate ASCII based (tabular or ASCII graphics) results depending on the problem type. The command line application felt is the only interface of the three analysis engines (felt, velvet, burlap) that is available under DOS.

    Velvet is the most powerful interface into the pre-programmed functionality of FElt - it allows for complete graphical problem definition through pulldown menus, popup dialog boxes and an interactive drawing area. It offers all of the capabilities of both felt and corduroy and has several options for post-processing, including color stress plots for planar elements, plots of the displaced structure, animation, graphical time-displacement plots for transient analysis problems, graphical frequency domain plots of transfer functions and output spectra for spectral analysis, and graphical plots of mode shapes for modal analysis problems.

    Burlap is the most powerful interface in terms of raw FE computing power simply because you can make it perform analyses that are not otherwise available in FElt simply by scripting your own analyses algorithms in burlap's powerful Matlab-like syntax. You can also use burlap to try out new element definitions quickly and easily or to manipulate the results from one of FElt's pre-programmed analyses in a novel way that is otherwise not provided for.

  3. Where can I get FElt?
  4. The latest version of FElt, in all its incarnations, is always available via anonymous ftp from ftp.felt.sourceforge.net. As of this update, the latest version is v3.05. Information is available via the Web at


    if you want to take a more serious look at some of FElt's capabilities before you actually take it for a test drive on your machine. There is an ftp mirror site at ftp.isd.uni-stuttgart.de in pub/src/FEM/Felt.

  5. What machines does FElt run on?
  6. The complete version of FElt (including the X11 based graphical user interfaces) has compiled and tested on HPs, DECs, Suns, SGIs, 386/486s running Linux and SysV R3, and IBM workstations. It should do the same on any reasonable Unix system with X11R5 or R6. In general we provide binaries for Sparc stations running SunOS or Solaris and 386s with Linux, but there is no guarantee that the binaries are as up to date as the source code. When in doubt just grab the source code and build it yourself - really, it's easy.

    DOS executables are available for the command-line applications felt, corduroy, yardstick, burlap, and patchwork. A simple graphical application, feltvu is also available. You need to have at least a 386 to use the DOS versions. As of v3.02 we have switched to DJGPP v2.0 and the DOS versions should run under Windows 3.1. Also as of v3.02, there are 32-bit Windows (95 and NT) versions of all the programs (including velvet). You need X server software to make velvet work of course.

  7. I think I found a bug, what now?
  8. Send one of us email (jgobat@mit.edu or atkinson@ucsd.edu). Please, please, please, include as much information as possible in your report. Things that are absolutely essential:

  9. Is there a newsgroup or mailing list for FElt?
  10. There was a real mailing list that is now dead. Instead we are manually maintaining a list of people who would like to receive periodic updates about releases and bug fixes. Send a note to jgobat@mit.edu indicating that you would like your name added to such a list. Incremental release announcements and bug fixes will be posted to the mailing list. Major release announcements will be made to the following newsgroups: comp.os.linux.announce, sci.math.num-analysis, sci.engr, sci.engr.civil, and sci.engr.mechanical. So if you really want to keep up on new versions and capabilities, you should subscribe to the mailing list.

  11. Why do the FElt components have such stupid names?
  12. Well, FElt is obvious, right? Finite ELemenT. felt the application came first - it's the most basic interface into the system. Now when it comes to fabrics, everybody knows that velvet is smoother than felt ... thus the slickest GUI interface is called velvet. xfelt is simply xfelt because it is nothing more than an encapsulator, with no real functionality beyond that provided by felt.

    After this, we start to stretch because with the felt - velvet connection we have this fabric motif to keep up on.

    - Burlap is rough but functional, just like its namesake fabric. It may not be as easy to use as velvet (or maybe it is if you like scripting in Matlab-like mathematical languages) but you can do an awful lot with it.

    - Corduroy has that regular ripple effect so its sort of like a mesh ...

    - Patchwork, well we figured that was better than convert simply to avoid conflicts. How many systems have some local app called convert to do whatever, or how many little hacks are there called convert. It seemed common enough to us that we figured we might as well call it something different. Patchwork implies a lot of different fabrics coming together so it seemed as good as anything else.

    - A yardstick is used to measure fabric ... measuring implies some sort of units.

Back to the FElt Demo Document.