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 thermo-rheologically simple (TRS) temperature dependence for time domain viscoelasticity Defining frequency domain viscoelasticity Specifying shear test data Specifying volumetric test data Specifying combined test data