FEM SolverCalculixCxxtools

    From FreeCAD Documentation

    FEM SolverCalculixCxxtools.svg FEM SolverCalculixCxxtools

    Menu location
    Solve → Solver CalculiX Standard
    Default shortcut
    S X
    Introduced in version
    See also
    FEM tutorial


    CalculiXccxTools enables usage of the CalculiX solver. It may be used for:

    1. Setting analysis parameters
    2. Selecting working directory
    3. Running the CalculiX solver


    1. A FEM SolverCalculixCxxtools.svg CalculiXcxxTools solver object is created automatically with the creation of an FEM Analysis.svg Analysis container.
      To create it manually, use one of the following alternatives:
      • Select Solve → FEM SolverCalculixCxxtools.svg Solver CalculiX Standard from the menu.
      • Press the S then X shortcut keys.
    2. Optionally change the properties of the FEM SolverCalculixCxxtools.svg CalculiXcxxTools solver object in the Property editor.
    3. Double click the FEM SolverCalculixCxxtools.svg CalculiXcxxTools solver object.
    4. Select the Analysis type.
    5. Click the Write .inp file button.
    6. Click the Run CalculiX button.


    Click the Edit .inp file button to display and edit the CalculiX input file manually before running the analysis. In that case it can be useful to set the DataSplit Input Writer property to true.


    Default values can be set in the menu Edit → Preferences → FEM → CalculiX

    • DataAnalysis Type:
      • static
      • frequency
      • thermomech - for mechanical and thermal loads
      • check - to check only the mesh
      • buckling - for buckling analyses introduced in version 0.20
    • DataBeam Shell Result Output 3D: note that CalculiX internally expands 1D and 2D elements into 3D elements to accomplish FE analysis
      • false - results of 1D and 2D elements will be averaged to the nodes of original 1D or 2D mesh (i.e. purely bended beam will show 0 nodal stresses due to averaging)
      • true - resulting mesh will contain 1D and 2D elements expanded to 3D elements
    • DataEigenmode High Limit: Eigenvalues above this limit will not be calculated; Note: if eigenvalues of the model are above the high limit, CalculiX will finish without output
    • DataEigenmode Low Limit: Eigenvalues below this limit will not be calculated
    • DataEigenmodes Count: number of lowest eigenmodes to be calculated
    • DataGeometric Nonlinearity:
      • linear - linear analysis will be performed if model does not contain nonlinear material
      • nonlinear - nonlinear analysis will be performed
    • DataIterations Control Parameter Time Use
      • true - activates DataIterations Control parameter Cutb and DataIterations Control Parameter Iter
      • false
    • DataIterations Thermo Mech Maximum: maximum number of increments in thermomechanical analysis after which the job will be stopped.
    • DataIterations User Defined Incrementations:
      • true - automatic incrementation control will be switched off by DIRECT parameter
      • false - incrementation control will be automatic
    • DataIterations User Defined Time Step Length:
      • true - activates DataTime End and DataTime Initial Step parameters
      • false
    • DataMaterial Nonlinearity:
      • linear - only linear material properties will be included in the analysis
      • nonlinear - nonlinear material properties will be used from FEM MaterialMechanicalNonlinear.svg Nonlinear mechanical material object
    • DataMatrix Solver Type: type of the solver to solve equation system inside FE analysis. It may significantly affect calculation speed and memory demands. Suitability depends on your FE model and available hardware
      • default - automatically selects matrix solver depending on available solvers (probably it will be Spooles)
      • spooles - direct solver with support of multiple CPUs. Number of CPUs need to be set in the preferences at Solver defaults → Number of CPU's to use.
      • iterativescaling - iterative solver with least memory demands, suitable if model contains mostly 3D elements
      • iterativecholesky - iterative solver with preconditioning with and with low memory demands, suitable if model contains mostly 3D elements
    • DataSplit Input Writer:
      • false - write whole input into one *.inp file to be used by CalculiX solver
      • true - split solver inputs into more *.inp files, that can clarify hand editing
    • DataThermo Mechanical Steady State:
      • true - steady state thermo mechanical analysis
      • false - transient thermo mechanical analysis
    • DataTime End: time period of the step, used when parameter DataIterations User Defined Incrementations or DataIterations User Defined Time Step Length is true
    • DataTime Initial Step: initial time increment of the step, used when parameter DataIterations User Defined Incrementations or DataIterations User Defined Time Step Length is true
    • DataWorking Dir: path to the working directory which will be used for CalculiX analysis files.


    When running a CalculiX, you might end up with error 4294977295. This means you don't have enough RAM space. You have then 2 options:

    1. reduce the number of mesh nodes, preferably by omitting geometry that is not absolutely necessary for your analysis
    2. buy more RAM for your PC


    Original CalculiX documentation can be found at http://dhondt.de/ in the "ccx" paragraph.