The development of a finite element model to simulate the sliding interaction between two, three-dimensional, elastoplastic, hemispherical asperities

The paper begins by identifying the need for a more realistic asperity-based contact model that accounts for the lateral flow of material during an asperity–asperity interaction. Consequently, a new finite element model is developed to simulate the sliding interaction between two, three-dimensional, elastoplastic, hemispherical asperities. Assuming a head-on contact configuration, three vertical overlaps and two values of interfacial friction are analysed. Using the new finite element model, solutions describing the normal and shear forces generated during the life cycle of an asperity contact are obtained for the first encounter. These results are then incorporated into a simple stochiastic model and used to predict the effect that surface roughness has on the overall friction coefficient. The findings show that the overall friction coefficient is lower if the asperities are regarded as spheres as opposed to cylinders. The fall in the friction coefficient is shown to result from the disproportionate lowering of the spherical forces caused by the lateral flow of the displaced material around the sides of the harder asperity.