A static friction model for the contact of fractal surfaces

A static friction model for elastic plastic contacting fractal surfaces was proposed based on the modified Majumdar and Bhushan (MB) model. In this model, four regimes were taken into account: fully elastic, first elastoplastic, second elastoplastic, and fully plastic of a deformed asperity contacting with a rigid surface. The work reveals that the static friction coefficient is determined by the material properties of rough surfaces, the fractal parameters for surface topography, and the normal load. Especially, from the results comparison and analysis, it was found that the present model is more complete than the MB model in describing the elastic plastic contacting fractal surfaces, and the results of the real contact area and the static friction coefficient predicted by the model are larger than those by the MB model for a range of fractal parameters studied. In addition, the results also show that the effect of the normal load on the static friction coefficient is contrary to that by the Chang, Etsion, and Bogy (CEB) friction model.