Solver CalculiX¶

In one sentence: Add a CalculiX solver to the analysis for structural, thermal, buckling, frequency, and electromagnetic analysis.

Overview¶

Workbench: FEM
Menu: FEM → Solve → Solver CalculiX

Adds a CalculiX solver object to the analysis. CalculiX (ccx) is the most widely used solver for FEM analysis in FreeCAD. It must be installed separately and its path set in Edit → Preferences → FEM → CalculiX.

Analysis types¶

Set the Analysis Type property to choose what CalculiX computes:

Analysis Type	What it solves
`static`	Linear or nonlinear static deformation under loads
`frequency`	Natural frequencies and mode shapes (modal)
`thermomech`	Thermal or thermo-mechanical analysis
`buckling`	Linear buckling load factor
`check`	Mesh quality check only
`electromagnetic`	Electrostatic analysis

Key properties¶

Property	Description
Analysis Type	See table above
Geometrical Nonlinearity	Enable large-deformation / nonlinear solve
Thermomech Type	Coupled / Uncoupled / Pure heat transfer
Iterations Control Max	Maximum nonlinear iterations
Eigenmode Number	Number of modes (frequency/buckling)

Common mistakes and pitfalls¶

CalculiX binary not found

Install CalculiX and set the path in Edit → Preferences → FEM → CalculiX. On Linux, which ccx gives the installed path.

Frequency analysis ignores loads

Modal analysis computes natural vibration modes — it ignores force and pressure loads. Run a separate static analysis for stress under load.

Python API¶

import ObjectsFem
doc = App.ActiveDocument
analysis = doc.getObject("Analysis")

solver = ObjectsFem.makeSolverCalculiX(doc, "CalculiX")
solver.AnalysisType = "static"
solver.GeometricalNonlinearity = "linear"
analysis.addObject(solver)
doc.recompute()