Tangential Contact Stiffness Model of Solid-Liquid Interface Under Mixed Lubrication

In order to analyze and predict the performance of mechanical structure and system, the tangential contact of solid-liquid interface under normal and tangential loads is studied, and the tangential stiffness model of rough surfaces is established by analyzing various contact states of the asperity under normal elastic-plastic deformation and tangential stick-slip. Based on the contact model of closed oil pits based on the influence of rough surfaces, on the basis of fully considering the influence of gradual application of load on the number of closed oil pit, and then changing the load distribution of solid-liquid interface, a liquid tangential stiffness model is established. The tangential stiffness of solid-liquid interface is obtained by two parts in parallel. Through simulation and experimental analysis, the effects of normal load, deformation and lubricant viscosity on the tangential stiffness of solid-liquid interface are revealed, and the tangential stiffness with or without lubricating medium is compared and analyzed. The results show that the tangential stiffness of solid-liquid interface and solid-solid interface increases nonlinearly with the increase of normal load and deformation. Due to the contribution of liquid stiffness, the tangential stiffness of solid-liquid interface is always slightly higher than that of solid-solid interface. The greater the viscosity of the lubricating medium, the greater the tangential stiffness of the solid-liquid interface. At low load, liquid contact is dominant, and the tangential stiffness of solid-liquid interface is low. Under moderate and heavy loads, the solid contact is dominant, and the tangential stiffness of the solid-liquid interface increases rapidly. Therefore, the tangential contact stiffness of the solid-liquid interface in mixed lubrication can be effectively improved by increasing the normal load and increasing the viscosity of the lubricating medium.