FEM ConstraintSelfWeight

    From FreeCAD Documentation

    FEM ConstraintSelfWeight.svg FEM ConstraintSelfWeight

    Menu location
    Model → Mechanical Constraints → Constraint self weight
    Workbenches
    FEM
    Default shortcut
    None
    Introduced in version
    -
    See also
    FEM tutorial

    Description

    Constraint self weight defines gravity acceleration 9,81 m/s^2 acting on the whole model in the prescribed direction.

    Usage

    1. There are several ways to invoke the command:
      • Press the FEM ConstraintSelfWeight.svg FEM ConstraintSelfWeight button.
      • Select the Model → Mechanical Constraints → FEM ConstraintSelfWeight.svg Constraint self weight option from the menu.
    2. You can modify the direction of gravitation by changing its vector coordinates in the property bar of newly created ConstraintSelfWeight object.

    Scripting

    New object:

    import ObjectsFem
    ObjectsFem.makeConstraintSelfWeight(name)
    

    Add object to the analysis named Analysis:

    App.ActiveDocument.Analysis.Member = App.ActiveDocument.Analysis.Member + [(object)]
    

    Example:

    import ObjectsFem
    selfweight_obj = ObjectsFem.makeConstraintSelfWeight("MySelfWeightObject")
    App.ActiveDocument.Analysis.Member = App.ActiveDocument.Analysis.Member + [selfweight_obj]
    

    Solver CalculiX

    Limitations

    • You need to modify .inp file to edit gravity acceleration.
    • Self weight is applied to the element set Eall means to the whole model.

    Editing CalculiX input file

    Acceleration constant can be edited by hand modification after generating CalculiX input file.

    Example of lines in .inp file:

    *DLOAD
    Eall,GRAV,9810,0.0,0.0,-1.0
    

    where 9810 is gravity acceleration magnitude in [mm/s^2], and 0,0,-1 is direction vector.

    Solver Z88

    • not implemented in Z88 solver (March 2017)