Modeling of Impact Plasto-Elastohydrodynamic Lubrication Problems—Consideration of Effects of Navier-Slip and Lubricant Rheology

Abstract In this research, a rigid ball impacting on an elastic half-space with lubricant in between is modeled by using the transient modified Reynolds equation, which considers the coupled effects of Navier-slip and flow rheology, the ball motion equation, and the deformation equations. In the impact-plasto-elastohydrodynamic lubrication (PEHL) point contact problems, the deformation mechanism consists of the elastic deformation based on linear elasticity, and the plastic deformation based on the flow rule and hardening model, as the von Mises stress is greater than the yield strength. The elastic-perfectly plastic (EPP) model is used first for basic studies, and the linear hardening model is used for further discussion. The impact-elastohydrodynamic lubrication (impact-EHL) model overestimates the central pressure, impact load, and minimum film thickness, while underestimating central film thickness and the position of minimum film thickness occurrence as compared to the present results from the impact-plasto-elastohydrodynamic lubrication (PEHL) model. As the slip length increases or the flow index decreases, the central film thickness decreases. For shear-thickening fluid (n > 1), the effects of slip weaken the shear-thickening effects, and make the central film thickness closer to that of a Newtonian fluid without slip. The effects of slip on the pressure distributions seem insignificant due to the force balance, and thus the central pressure and the elastic/plastic deformation. Moreover, the strain-hardening effect shows the inhomogeneous yield strength after one impact.