FElt

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. 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, 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 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.

 2007–2009 Alexey Beshenov.
Contact: al@cadadr.org.