Elastic-plastic nonlinear contact model for rough interfaces based on monotonically continuous contact pressure

The contact pressure of an asperity is the fundamental parameter for constructing a single asperity contact model and analyzing the contact load and contact stiffness of the mechanical joint surfaces. In response to the defects of existing models in contact pressure analysis that have non-monotonic changes or do not conform to physical laws, this paper proposes a novel nonlinear contact model that can achieve continuous monotonic changes in contact pressure in accordance with physical laws. This model considers the continuous deformation of the asperity after load application, and can describe three deformation states: elastic, elastic-plastic, and plastic during the loading process. For the elastic and plastic deformation stages, this paper characterizes them using the classic Hertz elastic contact theory and the complete plastic contact theory. For the elastic-plastic deformation stage, the contact pressure is characterized using an empirical pressure function, and expressions for other contact parameters are derived. Furthermore, based on the principle of probability and statistics, the solution expression for the contact parameters of the rough interface is obtained, and a novel rough interface contact model is established. By comparing with existing experimental and simulation results, it is found that: 1) The model in this paper achieves monotonic and continuous changes in contact pressure during the contact process of the asperity, while complying with physical laws; 2) The new model is in good agreement with experimental and simulation results, verifying the universal effectiveness and correctness of the proposed model in solving the contact parameters of the rough interface; 3) The new model has simplicity in expression and high computational efficiency.