A Quantitative Solution for the Full Shear-Thinning EHL Point Contact Problem Including Traction

Abstract

We present a realistic elastohydrodynamic lubrication (EHL) simulation in point contact using a Carreau-like model for the shear-thinning response and the Doolittle-Tait free-volume viscosity model for the piezoviscous response. The liquid lubricant modeled is a highviscosity polyalphaolefin which has been shown by highpressure viscometry to possess a relatively low threshold for shear-thinning as a single-component liquid lubricant. As a result, the measured EHL film thickness is about onehalf of the Newtonian prediction. We derived and numerically solved the two-dimensional generalized Reynolds equation for the modified Carreau model based on Greenwood. In this simulation, viscosity was not treated as an adjustable parameter; the models used for the pressure and shear dependence of viscosity were obtained entirely from viscometer measurements. Truly remarkable agreement is found in the comparisons of simulation and experiment for traction coefficient and for film thickness in both pure rolling and sliding cases.

Micro-Textures in Concentrated Conformal-Contact Lubrication: Effects of Texture Bottom Shape and Surface Relative Motion

“…Some verification and validation examples over a wide range of operating conditions through comparisons of experimental data and numerical results from different models can be found in [20,25,26], where validation efforts are made by comparing the numerical results with experimental data reported by other researchers. Good agreements have been found.…”

The Effect of Load (Pressure) for Quantitative EHL Film Thickness

“…A new ''quantitative approach'' to elastohydrodynamic lubrication (EHL) has emerged recently [1,2] wherein the behavior of the lubricated concentrated contact is calculated using accurate, measurable rheological properties of the liquid. For example, a full generalized Newtonian thermal EHL analysis, including the temperature and pressure dependence of the thermal properties of the liquid, has been obtained [3] for the film thickness and friction showing excellent agreement with experiment.…”

An Experimental Validation of the Recently Discovered Scale Effect in Generalized Newtonian EHL

“…Here, quantitative calculations of film thickness and friction [5][6][7] are obtained from the viscous properties which may be measured in viscometers. A first attempt has been made to include thermal feed-back in a quantitative manner [8] as well.…”