FEM EquationDeformation/de

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

1. After adding an Elmer solver as described here, select it in the tree view.
2. Now either use the toolbar button or the menu Solve → Mechanical equations → Deformation equation.
3. Change the equation's solver settings or the general solver settings if necessary.

Solver Settings

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

The deformation equation provides these special settings:

• DatenCalculate Pangle: If the principal angles should be calculated.
• DatenCalculate Principal: If all stresses should be calculated.
• DatenCalculate Strains: If strains will be calculated. This will also calculate the stresses, even if DatenCalculate Principal or DatenCalculate Stresses is false.
• DatenCalculate Stresses: If stresses should be calculated. Compared to DatenCalculate Principal the Tresca yield criterion and the principal stress will not be calculated.
• DatenInitialize State Variables: See the Elmer manual for more info.
• DatenMixed Formulation: See the Elmer manual for more info.
• DatenNeo Hookean Model: Uses the neo-Hookean material model.
• DatenVariable: 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 DatenMixed Formulation and DatenNeo 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:

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

Analysis Feature Information

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

• Fixed boundary condition
• Displacement boundary condition
• Force load
• Initial temperature condition
• Pressure load
• Gravity load
• Spring

• 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.

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