Effect of Asperity Interactions and Mesh Resolution on Friction Coefficient

Few models are devoted to explain the effect of surface roughness on the friction coefficient. Most of them use statistical approaches and do not incorporate the transition from elastic deformation to fully plastic flow. In this paper, a three-dimensional (3D) deterministic model is developed by considering different deformation modes of surface roughness which range from fully elastic through elastic–plastic to fully plastic contact interface. The simulations show that the increase in the surface roughness and mesh resolution lead to the increase in the static friction coefficient. For surfaces which present a low roughness, the static friction coefficient increases with increase in the normal load. The transition from elastic to plastic deformation is responsible for the increase of the friction coefficient with normal load. The comparison between experimental and numerical results reveals that the experimental friction coefficient is slightly larger than the calculated one. This difference does not exceed 10%. The multiscale roughness and the simplified geometry used to describe the shape of the surface roughness can explain the gap between experimental and numerical results in terms of friction coefficient.