On break-away forces in actuated motion systems with nonlinear friction

Abstract

The phenomenon of so-called break-away forces, as maximal actuation forces at which a sticking system begins to slide and thus passes over to a steady (macro) motion, is well known from the engineering practice but still less understood in its cause-effect relationship. This note analyzes the break-away behavior of systems with nonlinear friction, which is well-describable analytically by combining the Coulomb friction law with the rate-independent presliding transitions and, when necessary, Stribeck effect of the velocity-weakening steady-state curve. The break-away conditions are brought into an analytic form of the system description and shown to be in accord with a relationship between the varying break-away force and actuation force rate – that is observable in experiments reported in various independently published works.