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Nonlinear Mechanical Material

In one sentence: Add a plasticity model on top of an existing solid material to enable post-yield deformation in CalculiX nonlinear analysis.

Overview

Workbench: FEM
Menu: FEM → Model → Materials → Nonlinear Mechanical Material

Adds a plasticity model (FemMaterialMechanicalNonlinear) on top of an existing Material for Solid. This allows the material to yield — deform permanently when stress exceeds the yield point — rather than behaving elastically at all stresses.

When to use it

  • Stresses are expected to exceed the yield strength.
  • You need to predict permanent deformation (set) after unloading.
  • Required for CalculiX nonlinear static analysis.

Plasticity models

Model Description
Isotropic hardening Yield surface expands uniformly; suitable for most metals
Kinematic hardening Yield surface translates; better for cyclic loading

Step-by-step

  1. A Material for Solid must already exist in the analysis.
  2. Select the solid material object in the model tree.
  3. Choose FEM → Model → Materials → Nonlinear Mechanical Material.
  4. Set Yield Strength and Hardening Slope.
  5. Set the CalculiX solver's Geometrical Nonlinearity to On.

See also