Central film thickness formula for shear thinning lubricants in EHL point contacts under pure rolling

Based upon an extensive set of full EHL point contact simulations, this paper offers a central film thickness formula pertaining to shear-thinning lubricants with Carreau-type behavior. In order to develop a more generic and accurate version of film thickness formula, a recent work is extended by carrying out the simulations for widely varying operating loads and piezo-viscous coefficients along with the more realistic Doolittle's free volume based pressure–viscosity model. This equation is found to conform very well with the published experimental data for EHL lubricants with widely varying rheological and piezo-viscous behaviors, i.e., polyalpha olefins and polydimethyl siloxane.

► Offers a generic EHL film thickness formula for shear thinning lubricants.
► Intended to be used by tribological designers over a wide range of input parameters.
► Estimation of the shear-thinning parameters pertaining to Carreau-type lubricants.
► Good agreement between the experimental and curve fitted film thickness values.