Validation of EHL Contact Predictions under Time Varying Load

Abstract

In this paper, it is investigated how accurately current models predict the response of an elasto-hydrodynamically lubricated contact to time varying load conditions. For two patterns of time varying load, under conditions of pure rolling, the results obtained experimentally on a ball on disk interferometry apparatus by Sakamoto et al. (Behaviour of point contact EHL films under pulsating loads. Proceedings of the 30th Leeds-Lyon Symposium on Tribology, Elseviers Tribology Series, Vol. 43, pp. 391-399) are compared with the results of numerical simulations using the dynamic contact model of Wijnant (Contact dynamics in the field of elastohydro-dynamic lubrication. PhD Thesis, University of Twente, Enschede, The Netherlands, 1998 ISBN 90-36512239), Wijnant and Venner (Contact dynamics in starved elastohydrodynamic lubrication. Proceedings of the 25th Leeds-Lyon Symposium on Tribology, Elsevier Tribology Series, Vol. 36, pp. 705-716). The observed film changes are explained and related to the piezoviscous behaviour of the lubricant. Results for two different viscosity pressure relations are presented. It is shown that the details of the viscosity pressure relation have little effect on the local phenomena observed. The agreement between experimental and theoretical results is excellent in terms of the location and width of induced film thickness changes. The accuracy of the amplitude of the predicted changes is less. A amore accurate amplitude prediction requires more precise knowledge of the dynamic parameters, which describe the load system used in the experiments.