The simulation of wear processes is dominated by the feedback between system dynamics and wear, which have completely different characteristic time scales. We present a method for decoupling the time scales. Its central ideas are the introduction of a wear density on the entire wearing surface...

We study trajectories of mechanical systems with unilateral constraints under the additional assumption that always a given number of constraints is active. A reformulation as a problem with bilateral conditions yields a drastic reduction in the number of constraints, but in general, we are...