A multilevel computer simulation of friction and wear by numerical methods of discrete mechanics and a phenomenological theory

Abstract

A procedure for a multilevel computer simulation of friction and wear is proposed where numerical calculations at local contact scales by the method of movable cellular automata and a macroscopic phenomenological friction theory are chained together within a unified concept. For a mesoscopic simulation, use is made of the method of movable cellular automata in combination with numerical methods of continuum mechanics. Results obtained from a simulation of local contacts in contacting pairs of heterogeneous friction materials are reported. The effect of the initial surface microroughness on a quasi-fluid layer in the contact zone of plastic materials is examined. The macroscopic phenomenological model for friction describes spalling, reintegration of wear debris into the wear surfaces and mass transfer from one contacting body to the other, using stochastic differential equations. The parameters of the phenomenological equations are found solely by means of microscopic models for processes involved in a tribological contact. It is suggested that a simulation by the method of movable cellular automata be used to this end. The procedure developed enables the effective diffusion coefficient of the friction layer to be estimated. Identification of the parameters of the macroscopic model is made possible by simulating the processes operative at the nanoscale level thus bridging nano- and macroscale levels.