Recent Trends in Numerical Analysis of Elastohydrodynamic Grease Lubrication

Abstract

This article reviews some of the research on numerical analysis of elastohydrodynamic grease lubrication and on relevant models of grease aging and bleeding, aiming at a better understanding of the underlying phenomena. Several degradation models have been developed to describe the influence of shear and temperature on the reduction of the yield stress. The feed-loss balance model, which is generally applied to rolling bearings, is also applied to seals to predict the film thickness decay in an axial lip contact. Grease EHL theory that takes grease as a non-Newtonian fluid has been developed. A numerical analysis is recently performed to predict the grease film thickness at low speeds, which can be significantly larger than the base oil film thickness due to increase in the yield stress, which is due to increase in the thickener concentration. The model is detailed to clarify the mechanism of the increase in the thickener concentration.