Simulation of microscopic elastic-plastic contacts by using discrete dislocations

A new method for simulation of microscopic elastic-plastic contacts, such as those between surface microasperities, is developed. Asperity plastic deformation is described in terms of nucleation and motion of discrete crystal dislocations, which allows the model to be made scale-sensitive. The new method allows elastic-plastic microcontacts to be investigated on the scales too small to apply conventional continuum mechanics methods, but still too large for atomistic simulations. Using the developed method, several microcontact simulations are performed. The junction growth effect for asperity microcontacts is studied and found to be very strong in certain cases. Subsurface stress distributions at an asperity microcontact are analysed. High-magnitude tensile stress spikes, apparently caused by groups of dislocations piling up against one another, are found below the contact area. Interaction between a pair of microasperities is simulated and an estimation of the plasticity contribution to friction is obtained. The new approach appears promising, although the present model is simplistic.