Abstract

Dry frictional contact between two steel surfaces in a harmonically forced spring–mass system is investigated both experimentally and numerically. The experimental set-up is somewhat novel in that the spring–mass system is excited through the frictional interface, facilitating detailed study of interactions between the system's dynamic characteristics and the stick–slip motion observed at the interface. A characterization of the effect of wear upon observed stick–slip is given, resulting in the identification of three sliding regimes displaying varying degrees of wear. Subsequent attention is focused primarily on the first of these regimes, the low wear regime, which features low frequency stick–slip oscillations that can be measured quite reliably. This work particularly emphasizes the nature of transients entering and exiting stick phases, with several representations given of the evolution of these transients as control parameters are changed. Multiperiod and chaotic motions of the mass are also observed, with routes to chaos being qualitatively similar for a wide range of system parameters. The work also presents some numerical results in support of the experimental work, utilizing a rate- and state-dependent friction model proposed previously by the authors. It is seen that this model yields significantly better predictions than can a simple Coulomb representation.