A complete contact model of a fractal rough surface

This study suggested a revision to the contact model of a fractal rough surface, by extending the modified asperity contact model developed by Morag and Etsion, into a complete contact model of a fractal surface. According to the modified asperity model, the critical area of a single asperity was scale dependent and that the asperity's plastic to elastic mode transition agreed with classical contact mechanics. The total load, area and stiffness of a fractal rough surface were studied, and obtained by summing over the contact force, area and stiffness of the asperities at all length scales. The results revealed that the contact area depended linearly on the contact load and that the contact stiffness increased with increasing contact load. The share of plastic contact area decreased as the contact load increased. The impact of the fractal roughness parameter G and fractal dimension D on the contact stiffness was also discussed, and the results showed that the rougher the surface became, corresponding to a smaller value of D and a larger value of G, the smaller the contact stiffness was.