DISTRIBUTION OF ESCAPE TIMES OVER A FLUCTUATING BARRIER IN A MECHANICAL SYSTEM

Abstract

We consider the problem of transitions between states of a bistable mechanical system induced by a harmonically, and a randomly oscillating barrier. We study the problem both experimentally and numerically. The system consists of a mass attached to a rotating disk, nonlinearly coupled to a spring subject to an external force. For periodically driven external forces, the transition rate across the barrier increases linearly with the frequency of the driving force until the system reaches the boundary of a chaotic region. Beyond this boundary, the rate drops sharply until it is fully suppressed at the end of this region. When the driving force is stochastic we find that the transition rate also has a maximum, and that its position depends on the rate of switching of the random force.