Numerical Analysis of the Oil-Supply Condition in Isothermal Elastohydrodynamic Lubrication of Finite Line Contacts

In order to investigate the effect of oil-supply condition on the lubrication performance of machine components, such as gears and roll bearings, a full numerical solution of the isothermal finite line contact elastohydrodynamic lubrication (EHL) problem under different oil-supply conditions was obtained. The supplied oil quantity was given with the thicknesses of layers of oil films on both solid surfaces, and an equivalent thickness of such supplied oil films was introduced. An algorithm similar to that proposed by Elrod in 1981 was developed to determine the pressure starting position automatically. The pressure field was solved with a multi-grid solver which enables the difficulty of the huge mesh differences in two directions be overcome easily. The surface deformation produced by pressure was calculated with a multilevel multi-integration method. Based on the Newtonian lubricant assumption, comparisons of solutions between the starved and fully flooded contacts have been made. Results show that the pressure starting position and the central and minimum film thicknesses vary with different oil-supply thicknesses. In addition, the influence of the thickness of the oil-supply layer, the end profile radius, the entrainment velocity, and the maximum Hertzian pressure on the starved fluid film thickness has been investigated. In conclusion, the optimum quantity of the supplied oil is very important for the discussed problem.