A physics-based model to predict micro-pitting lives of lubricated point contacts

Abstract

This paper proposes a physics-based model to predict the onset of micro-pit formation for lubricated point contacts of rough surfaces. A mixed elastohydrodynamic lubrication model is employed to predict the surface normal and tangential tractions for a stress prediction model to determine the resultant stress histories. The boundary element approach is used in the stress model to fully capture the measured three-dimensional topographies of the contacting rough surfaces, allowing an accurate prediction of the localized stress concentrations that dictate the occurrence of micro-pits. In the process, the method of coordinate transformation and the indirect approach of rigid body motion are devised to eliminate the kernel singularities. A novel numerical procedure is also developed to minimize any Gaussian quadrature numerical error in the integration of the near singular kernels. The fatigue damage is then evaluated employing a multi-axial fatigue criterion. The proposed micro-pitting life prediction methodology is demonstrated using an example ball-on-disk contact problem.