*GLOBAL DAMPING

Optional parameters

ALPHA

Set this parameter equal to the ${\alpha }_{global}$ factor to create global Rayleigh mass proportional damping $D_{\alpha }={\alpha }_{global}*M$, where $M$ denotes the model mass matrix. The default is ALPHA=0. (Units of T⁻¹.)

BETA

Set this parameter equal to the ${\beta }_{global}$ factor to create global Rayleigh stiffness proportional damping $D_{\beta }={\beta }_{global}*K$, where $K$ denotes the model stiffness matrix. The default is BETA=0. (Units of T.)

FIELD

Set FIELD=ACOUSTIC to apply the global damping only to the acoustic fields in the model.

Set FIELD=ALL (default) to apply the global damping to all of the valid displacement, rotation, and acoustic fields in the model.

Set FIELD=MECHANICAL to apply the global damping only to the valid displacement and rotation fields in the model.

This parameter is not supported in a mode-based steady-state dynamic analysis that uses coupled acoustic-structural modes.

STRUCTURAL

Set this parameter equal to the $s_{global}$ factor to create frequency-independent stiffness proportional structural damping $D_s=i{s}_{global}*K$, where $K$ denotes the model stiffness matrix. The default is STRUCTURAL=0.