Inelastic Strain Rate
The Inelastic Strain Rate node allows to enter inelastic strain contributions to the Linear Elastic Material, Nonlinear Elastic Material, and Hyperelastic Material models on a variety of formats. As opposed to the External Strain feature, the inelastic contribution is given as a strain rate, and the inelastic contribution is added after integrating this rate in time.
The Inelastic Strain Rate node is only available with some COMSOL products (see https://www.comsol.com/products/specifications/). The node is available for 3D, 2D, and 2D axisymmetry.
Shell Properties

This section is only present when Inelastic Strain Rate is used as a subnode to:
Linear Elastic Material in the Layered Shell interface. See the documentation for the Inelastic Strain Rate node in the Layered Shell chapter.
Linear Elastic Material, Layered and Hyperelastic Material, Layered in the Shell interface. See the documentation for the Inelastic Strain Rate node in the Shell and Plate chapter.
Linear Elastic Material, Layered in the Membrane interface. See the documentation for the Inelastic Strain Rate node in the Membrane chapter.
Coordinate System Selection
Select a Coordinate system. All inputs are interpreted in the given coordinate system. This also implies that external code should assume that strains are passed with its local orientations. Deformation gradients are rotated by the local system in both indices.
Inelastic Strain
Select the type of Strain inputStrain tensor, Deformation gradient, Deformation gradient, inverse, or Stretches.
The option Strain tensor is not available for a Hyperelastic Material or Layered Hyperelastic.
The options Deformation gradient, Deformation gradient, inverse, and Stretches are not available with Linear Elastic Material, Layered in the Shell interface.
Initial value
Enter an initial value for the inelastic quantity as specified by the Strain input setting.
Time Stepping

This section is not present when Inelastic Strain Rate is used with:
Linear Elastic Material, Layered and Hyperelastic Material, Layered in the Shell interface.
Linear Elastic Material, Layered in the Membrane interface.
Select a MethodAutomatic, Backward Euler, or Domain ODEs.
Automatic
The Automatic option corresponds to the backward Euler method except with predefined settings for the Newton loop used to solve the local equations.
Backward Euler
For the Backward Euler method, enter the following settings:
Maximum number of local iterations. To determine the maximum number of iterations in the Newton loop when solving the local time-dependent equations.
Absolute tolerance. To check the convergence of the local equations based on the step size in the Newton loop.
Relative tolerance. To check the convergence of the local equations based on the step size in the Newton loop. The final tolerance is computed based on the current solution of the local variable and the entered value.
Residual tolerance. To check the convergence of the local equations based on the residual of each equation.
If both a step size and residual convergence check is requested, it is sufficient that either of the conditions are fulfilled. Setting either the Absolute tolerance and Relative tolerance or the Residual tolerance to zero ignores the corresponding convergence check. An error is returned if all are set to zero.
Domain ODEs
No settings are needed for the Domain ODEs method. However, this method adds degrees-of-freedom that are solved as part of the general solver sequence. The scaling of these fields can affect the convergence of the overall solution
See also Inelastic Strain Rate in the Structural Mechanics Theory chapter.
Location in User Interface
Context Menus
Ribbon
Physics tab with Linear Elastic Material, Nonlinear Elastic Material, Hyperelastic Material, Linear Elastic Material, Layered, or Hyperelastic Material, Layered node selected in the model builder tree: