A new method was developed for simulating microscopic elastic-plastic contacts, such as those between surface micro-asperities. The asperity plastic deformation was described in terms of the nucleation and motion of discrete crystal dislocations. The new method permitted elastic-plastic micro-contacts to be investigated at scales which were too small for the application of conventional continuum mechanics methods, but too large for atomistic simulations. The junction growth effect for asperity micro-contacts was studied and was found to be very strong in certain cases. Sub-surface stress distributions at an asperity micro-contact were analyzed. High-magnitude tensile stress spikes, which were apparently caused by groups of dislocations piling up against one another, were found below the contact area. The interaction between a pair of micro-asperities was simulated, and an estimate of the plasticity contribution to friction was obtained. The new approach appeared to be promising, although the present model was simplistic.

Simulation of Microscopic Elastic-Plastic Contacts by using Discrete Dislocations. I.A.Polonsky, L.M.Keer: Proceedings of the Royal Society A, 1996, 452, 2173-94