FEM CalculiX

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This page collects all informations about the current solver used by FreeCAD's FEM Module. The interface between the solver and FreeCAD in pre- as well as post processing is also described. At the moment (Begin 2016 and FreeCAD 0.16dev) the only supported solver by the FEM Module is [CalculiX]. Depending on the operating system you are working with you need to install CalculiX first. Check out [FEM Install].


Interaction between FEM Module and CalculiX is done by text files. The FEM Module writes a CalculiX input file, starts CalculiX, logs the output of CalculiX and read the output files of CalculiX if they are available. The FEM Control Solver tool manages the whole process. User interaction in the process is possible.

Preprocessing interface

CalculiX uses abaqus input file format. The input file could be edited before the solver is started. The units used in the CalculiX input file are independet from the units used in FreeCAD. They will be mm and N. (ToDo: check this. What happens with the mesh if inch is used in FreeCAD. Density was introduced. With this we have kg and s and no longer N?! how about this !?!)

The FEM Module - CalculiX interface supports the following objects:

FEM Elements
  • linear static analysis
  • Frequency analysis
  • Coupled thermal structural analysis
  • one linear elastic isotropic (uniformity in all directions) material
  • multiple material is in development

Postprocessing interface

read resulting stress (Von Mises) and all displacement