The isotropic hardening model for the flow stress hardening model is defined with the
ISOTROPIC HARDENING MODELcommand line.The function name of a user-defined isotropic hardening model is defined via the
ISOTROPIC HARDENING FUNCTIONcommand line.The optional rate multiplier for the flow stress hardening model is defined with the
RATE MULTIPLIERcommand line.