Extrapolated equation for grease film thickness in counter-formal EHL contact conjunction

Abstract

Grease lubricants behave as pseudo-plastic fluids i.e. their viscosity reduces under shear. With sufficient shear, the viscosity of grease approaches that of the base lubricant. This behaviour means that grease may be considered as a plastic fluid. Though, the numerical solutions for oil lubricants have been presented, that of the modified Reynolds equation for grease for point contacts remains challenging despite the advent of powerful computational techniques and platforms. In this work grease lubricated concentrated point contacts are analysed under isothermal conditions. Dimensionless control parameters are used to define the operating conditions in the contact conjunctions. The asymptotic behaviour of grease allows for the development of film thickness equations. From the results of the numerical method, an extrapolated equation for grease film thickness for piezo-viscous elastic EHD regime of lubrication is developed using the dimensionless parameters.