High-pressure rheology of lubricants and limitations of the Reynolds equation

Tribology, lubricants and lubrication engineering — a review

The rheological response of lubricants to a combination of shear and hydrostatic pressure has held the interest of tribologists working in elastohydrodynamics since it became accepted that thin lubricant films transfer the shear between solids in concentrated contact. Recently developed techniques allow us to probe the shear and bulk behavior of liquids at pressures and rates which overlap the conditions of lubricated concentrated contact. Results of high-pressure rheometry can be used to successfully predict EHD traction. It is now possible to actually view liquids in shear and in compression at high-pressure. Although with the proper assumptions valid traction predictions can be obtained using the concept of homogeneous shear in the load bearing region, flow visualization results require that we rethink previously held concepts of non-Newtonian flow at high-pressure.

“Recent Developments in High-Pressure Rheology of Lubricants”

High-pressure viscosity prediction of di(2-ethylhexyl) phthalate and tricresyl phosphate binary mixtures using dielectric relaxation data

A simplified impact microviscometer

Recent investigations of EHD lubrication have indicated the importance of viscoelastic properties in explaining the differences in the behavior of different lubricants. Up to the present time, however, very little of the data necessary to develop a reliable viscoelastic model of EHD lubrication has been available. It is the purpose of this article to present a description of recently developed high pressure light scattering techniques which for the first time make an extensive study of the pressure and temperature dependence of the viscoelastic properties of lubricants feasible. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Montreal, Canada, October 8–10, 1974

T. A. Litovitz

Papers

The Study of Viscoelastic Properties of Lubricants Using High Pressure Optical Techniques