AudiLabFod: Finite-element postprocessor

Fod is a home-grown programme for displaying the results of 3-D finite-element simulations. It takes as input the simulation-result files created by Sap, including the .res plain-text file and (for time-domain simulations) the .hist binary file.

Fod is implemented in Fortran. It was originally developed under VMS, and is currently being developed under Compaq (Digital) Unix for Alpha; GNU/Linux for Alpha and Intel; and (alas) Microsoft Windows. The binary is available for Unix and GNU/Linux by request; the binary for Windows is offered here. It can be used for any purpose as long as I am informed of its use. So far there is no documentation beyond what you're looking at.


Installation under MS Windows 95/98/NT/2000

Either download the Fod executable for 32-bit Windows (about 1.5 Mbytes) or (if your computer is part of the McGill BME network) create a shortcut to the executable on probeShare. Follow the general instructions for installation of Dip software.

Installation under GNU/Linux

Fod for 64-bit GNU/Linux can be downloaded here:

Usage tips

If you specify the name of an input file on the command line when you start Fod, you will immediately be asked where the graphics should be sent to (Plotting to?); you can also specify what graphics output type to use. To have the graphics displayed on the screen, just hit the Enter key. If you don't specify an input file when starting Fod, you should immediately be presented with a menu for selecting which .res file to open. See instructions for using Dip file menus.

From the next menu, normally select ‘No summary output’.

For the question about dropping inside faces, normally just hit the Enter key for the default. For the question about double-precision floating-point format, normally just hit Enter for the default.

For the question about the mode, if you type '?' (followed by Enter) you will see a list of the possible modes. Normally accept the default (DA) or type DW or DV. All three choices request display of displacements. If you select DA or DW, the next question will be about which displacement component you wish to display. The answer should be an integer from 1 to 6 for DA, or 1 to 3 for DW, or 0 (zero) to display the magnitudes of the displacement vectors.

Normally accept the default for the question about units.

If you specified DA or DW, normally accept the default of C to display contours, then accept the default for the number of contours. If you specified DV, specify either A to display arrows for the displacements, or D to display displaced surfaces; accept the defaults for the following question(s) about arrow sizes or maximum displacement.

To begin with, you can just type Enter for the following questions: plotting profiles, element selection, minimum plotting level, triangle fill, angles, the range of coördinates (Wxmin, etc.), load case, and range for contours.

Once the results have been displayed, you can type Q to quit; type V to export a VRML file containing a 3-D model with displacement vectors added; specify a different graphics output type; or just type Enter to go back and revise your display choices.

For the Angles question, either (1) enter a set of 3 values (in degrees) for the desired rotations about the x, y and z axes; or (2) enter either X, Y or Z. In the latter case, you will then be asked for the rotation angle to be applied about the specified axis.


In fodh_read_displacements, displacements are read into HDISP for all calculation requests (1 to Nrqc) and for all time steps (1 to Ntstep). DISPL is used to buffer the displacements for 1 time step at a time.

In fodh_fft, for each calculation request, the time response is differentiated and FFT-transformed, and the gains (magnitudes) and phases are stored in HFFTG and HFFTP.

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R. Funnell
Last modified: 2020-03-07 13:35:26