On the coupling of the elastohydrodynamic problem

Abstract

The paper presents the results of an investigation of methods of mathematically coupling the equations of elastohydrodynamic lubrication (EHL) that define the EHL line contact problem. The objective is to develop numerical solvers for use in the study of thin-film/rough surface contacts such as found in gears. It has been found that deformation behaviour of the surfaces is a dominant effect and that full rather than partial coupling is necessary for stable solutions. For cases considered using a Newtonian lubricant a first-order formulation of the Reynolds equation is required at high loads in the high-pressure part of the contact. The fully coupled method is also applied to contact between a moving smooth surface and a stationary rough surface. The significant changes brought about by non-Newtonian oil behaviour are demonstrated, together with the ability of the method to provide solutions for cases where the λ ratio (of film thickness to surface roughness) is as low as 0.1.