To represent strain rate dependent elastic behavior, a
linear viscoelastic model can be used. The shear modulus in the relaxed state is
described by the long-term shear modulus 
. Viscoelastic behavior is introduced via an
instantaneous shear modulus 
and a viscoelastic decay constant 
. The viscoelastic deviatoric stress at time increment n+1 is
calculated from the viscoelastic stress at time increment n and the deviatoric
strain increments at time increment n via
where
| is the long-term shear modulus of the material. This value is
derived from linear elastic properties or defined directly using the equation of
state, shear modulus property. |
 is the instantaneous shear modulus of the material. |
 is the viscoelastic decay constant. |
The deviatoric viscoelastic stress is added to the elastic stress to give the total stress at the end of each cycle.
Note: The model must be combined with either the linear elastic property or an equation of state property (including shear modulus).
The model can only be applied to solid bodies.
Table 11.1: Input Data
| Name | Symbol | Units | Notes |
|---|---|---|---|
| Instantaneous Shear Modulus (High rate) |  | Stress | |
| Viscoelastic Decay Constant |  | 1/ time |
Custom results variables available for this model.
| Name | Description | Solids | Shells | Beams |
|---|---|---|---|---|
| VTXX | Viscoelastic stress XX | Yes | No | No |
| VTYY | Viscoelastic stress YY | Yes | No | No |
| VTZZ | Viscoelastic stress ZZ | Yes | No | No |
| VTXY | Viscoelastic stress XY | Yes | No | No |
| VTYZ | Viscoelastic stress YZ | Yes | No | No |
| VTZX | Viscoelastic stress ZX | Yes | No | No |