A Multi-Scale Contact Model for Rough Surfaces Under Loading and Unloading Conditions

The contact of rough surfaces is a fundamental issue in analyzing friction, wear, and assembly of two parts. This study developed a multi-scale contact model for rough surfaces. Shoulder-shoulder elastoplastic contact, substrate deformation, and asperity interaction were considered in the asperity scale. A fractal representation was introduced to the contact model in the rough-surface scale, where the critical length scale and critical contact area were determined in the asperity scale. The proposed contact model was validated through comparisons with experimental data, simulation results, and other analytical models. Then, the effects of the surface topography, material properties, and largest length scale on rough-surface contact were examined, and the difference between the shoulder-shoulder and tip-tip contact modes was clarified.