Keyword type: step
This procedure is used to perform a static analysis for materials with viscous behavior. The syntax is identical to the *STATIC syntax, except for the extra parameter CETOL. This parameter is required and defines the maximum difference in viscous strain within a time increment based on the viscous strain rate at the start and the end of the increment. To get an idea of its size one can divide the stress increase one would typically allow within a time increment by the E-modulus.
Although the specification of the CETOL parameter is mandatory, it is only used so far for materials for which the elastic behavior is linear and isotropic.
Notice that the default way of applying loads in a *VISCO step is step loading, i.e. the loading is fully applied at the start of the step. This is different from a *STATIC step, in which the loading is ramped. Using a *VISCO step only makes sense if at least one materials exhibits viscous behavior.