4.4. Damping Extraction for Large Signal Cases

If a structure does not undergo significant deformation, the gap between the structure and the fixed wall may be assumed to be constant (small signal case). If the structural deformation in the gap is significant, the change in the gap may effect the damping of the structure (large signal case). The gap is defined as a real constant in the thin-film fluid elements. Use SETFGAP to automatically define and/or update the gap real constants for the thin-film FLUID136 elements. The command can be used to:

Create real constant table entries for every selected FLUID136 element (large signal case).
Update an existing real constant table according to structural displacements for every FLUID136 element (large signal case).

This option allows you to check the dependence of the damping parameters over the deflection range of the structure.