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FEM EquationDeformation

From FreeCAD Documentation

FEM EquationDeformation

Menu location
Solve → Mechanical Equations → Deformation Equation
Workbenches
FEM
Default shortcut
None
Introduced in version
0.21
See also
Elasticity equation, FEM tutorial

Description[edit | edit source]

This equation describes the nonlinear elastic deformation of solid bodies.

For information about the math of the equation, see the Elmer models manual, section Finite Elasticity.

Usage[edit | edit source]

  1. Add an Elmer solver.
  2. Select it in the Tree View.
  3. There are several ways to invoke the command:
    • Press the Deformation Equation button.
    • Select the Solve → Mechanical Equations → Deformation Equation option from the menu.
  4. Change the equation's solver settings or the general solver settings if necessary.

Solver Settings[edit | edit source]

For the general solver settings, see the Elmer solver settings.

The deformation equation provides these special settings:

  • DataCalculate Pangle: If the principal angles should be calculated.
  • DataCalculate Principal: If all stresses should be calculated.
  • DataCalculate Strains: If strains will be calculated. This will also calculate the stresses, even if DataCalculate Principal or DataCalculate Stresses is false.
  • DataCalculate Stresses: If stresses should be calculated. Compared to DataCalculate Principal the Tresca yield criterion and the principal stress will not be calculated.
  • DataInitialize State Variables: See the Elmer manual for more info.
  • DataMixed Formulation: See the Elmer manual for more info.
  • DataNeo Hookean Model: Uses the neo-Hookean material model.
  • DataVariable: The variable for the deformation equation. Change there the 3 to 2 if you have a 2D geometry. For the special case that you have DataMixed Formulation and DataNeo Hookean Model set to true, the variable number must be geometry dimensions + 1, so for 3D geometry the 3 must be changed to 4.

Equation:

  • DataPlane Stress: Computes solution according to the plane stress situation. Applies only for 2D geometry.

Analysis Feature Information[edit | edit source]

The deformation equation takes the following analysis features into account if they are set:

Note[edit | edit source]

  • Except for calculations in 2D, for all the above analysis features it is important that they act on a face. Features in 3D set to lines or vertices are not recognized by the Elmer solver.

Results[edit | edit source]

The available results depend on the solver settings. If none of the DataCalculate * settings was set to true, only the displacement is calculated. Otherwise also the corresponding results will be available.