Fractal Prediction Model for the Contact of Friction Surface and Simulation Analysis

Based on fractal theory, the contact prediction model of rough friction surface has been established, considering the relative sliding between asperities of friction surface and the influence of material hardness on the change of surface depth during the elastoplastic deformation. The relationship between the total contact load and the actual total contact area is obtained. The existing conditions of elastic deformation, elastoplastic deformation and completely plastic deformation of single asperity are obtained and the mathematical expressions of critical elastic deformation real micro-contact area and critical plastic deformation real micro-contact area are derived. The numerical results show that: when the material properties and friction coefficient are constant, actual total contact area rises with the rises of the total contact load, and the smoother the friction surface is, the larger the increase of the actual total contact area is; when the total contact load and material property parameters of friction surface are constant, the actual total contact area increases at first and then decreases with the increase of the fractal dimension of friction surface, and decreases with the increases of fractal scale coefficient; when the total contact load and the fractal dimension are constant, with the increase of the material hardness, the actual total contact area decreases. This contact prediction model is helpful to study the real contact situation between friction surfaces and provides a theoretical basis for further study of the friction and wear mechanism between friction surfaces.