Detection of asperity dynamic impacts on lightly loaded random surfaces

Abstract

A general formulation is presented for the analysis of dynamic interactions of random surfaces. The analysis is applied to the case of two surfaces whose topographical spacings follow a gaussian distribution and is used to predict theoretically the characteristics of the frequency content in the vibration response of a simplified elastic system. An experimental investigation of the fundamental parameters of the phenomenon, using a special test rig and data acquisition system, was also conducted. In the experiment, hard surfaces covered with silicon carbide grains were rubbed under light normal loading to simulate a dry friction interface where asperity failure becomes most likely owing to fatigue of coupling junctions. Experimentally obtained results were observed to be consistent with the theoretical predictions in that random micro-impacts between surface asperities make a distinct contribution at the onset of individual friction resistances developed in the interface.