Damping for Piezoelectric Actuator

[Brazensage]

I am doing a transient contact analysis of an ultrasonic motor that vibrates in the y-direction, but moves linearly in the x. It is a 2-D simultation. There are feet on the actuator that contact a surface to allow it to move forwards via friction. I have modeled the feet and surface as a node-line flexible-flexible contact problem. What I see is that at the beginning of the Analysis the actuator bounces very high off of the ground (there is some bounce but this is a bit too much). It also bounces too much in the steady state. I have refined the mesh, decreased timestepping, decreased normal stiffness, etc to no avail. I need the surface the feet impact to impart a sort of "coefficient of restitution" to the feet. Using APDL 12.0 there isn't a way to do this other then COMBIN40 I was told. Unfortunately as soon as I put COMBIN40 elements in with a large damping coefficient and very low gap to do this, the problem does not converge.

Does anyone know of a way to implement a coefficient of restition to dampen some of this bouncing? Is there a way to get of the high initial bounce?