You can define viscoelastic behavior in a material as a function of frequency (for steady-state, small-vibration analyses) or as a function of reduced time (for time-dependent analyses). For more information, see the following sections:
Time domain viscoelasticity
Frequency domain viscoelasticity
Defining viscoelastic materials Defining time domain viscoelasticity Specifying thermorheologically simple (TRS) temperature dependence for time domain viscoelasticity Defining frequency domain viscoelasticity Specifying shear test data Specifying volumetric test data Specifying combined test data