Solver Settings for Viscoelasticity, Creep, and Viscoplasticity
Viscoelasticity, creep, and viscoplasticity are time-dependent phenomena. The time scale, however, is often such that inertial effects can be ignored. When that is the case, you can modify the solver settings to improve the performance of the time-dependent analysis.
Physics Interface Settings
In the Model Builder, click the Solid Mechanics node. In the Settings window, under Structural Transient Behavior, select Quasi static to treat the elastic behavior as quasi static (with no mass effects; that is, no second-order time derivatives for the displacement variables). Selecting this option gives a more efficient solution for problems where the variation in time is slow when compared to the natural frequencies of the system since no mass matrix will be created.
Solver Settings
When Quasi static is selected on the physics interface Settings window, the automatic solver suggestion changes the method for the Time Stepping from Generalized alpha to BDF.
For a Fully Coupled node (or Segregated node for multiphysics problems), the default Nonlinear method under Method and Termination is Automatic (Newton). To get a faster computation time when the strain rate is low or moderate, select Constant (Newton) as the Nonlinear method instead.
In the COMSOL Multiphysics Reference Manual: