Effect of plasticity and coalescing for neighboring asperities in contact with a rigid flat

The contact behaviors of rough surfaces, which consist of asperities with random geometric properties at small length scale, have been extensively investigated on contact behaviors in engineering and scientific research. Due to the complexity of loading condition and surface topography, the limitation of traditional statistical model leads to the inaccuracy of prediction for rough surface contact behaviors. Starting from the multi-asperity contact theory, we release the restrictions of classical GW model and propose an elastic-plastic interacting model to investigate the coalescence effect of neighboring asperities in this paper. Through numerous simulations and analyses, the results show that the plasticity can be measured by material and morphology parameters. With the increasing of plasticity and the decreasing of asperity peak distance, the contact interface transits from interaction dominated to coalescence dominated contact relationships. With the increasing of loading, the shape of contact zone changes from two independent circles with expanding radius to a joint point, and finally the contact zone becomes a single ellipse. The coalescence status of neighboring asperities is influenced by the plasticity and the initial distance between asperity peaks. Our study provides some basis for establishing a statistical or discrete rough surface model considering merging, predicting the contact behaviors between solids, and revealing the evolution of contact spot information.