THE INFLUENCE OF PIEZO-VISCOUS LUBRICANTS ON EHL LINE AND POINT CONTACT PROBLEMS

A good and accurate prediction of the elastohydrodynamic lubrication behaviour requires consideration of the constitutive equation for the lubricant. In particular, for applications involving synthetic oils or mineral oil with polymeric additives that exhibit shear-thinning behaviour, the use of an appropriate pressure-viscosity relationship for the lubricant is required to predict the EHL behaviour more accurately [1-3]. For this reason, this paper aims to emphasize the importance of implementing piezoviscous models with accurate treatment methods in EHL applications. Due to the high pressure in an EHL contact, in fact, the elastic deformation of the surfaces and pressure dependence of viscosity play the pivotal role and in many applications, the lubricant exhibits a shear-thinning behaviour which significantly affects the film thickness [4-6]. The effects of different pressure–viscosity relationships, including the exponential model, the Roelands’ model and specifically, the Doolittle model are investigated and a generalized formulation that can efficiently treat shearthinning fluids with provision for compressibility in the EHL contact is presented