On the time-dependent, thermal and non-Newtonian elastohydrodynamic lubrication of line contacts subjected to normal and tangential vibrations

Abstract

Complete numerical solutions were obtained for the time-dependent thermal elastohydrodynamic lubrication (EHL) of line contacts under combined vertical and longitudinal vibrations. It was assumed that the contact was composed of two infinitely long steel rollers. These rollers were then simplified as an infinite plane and an equivalent roller. The lubricant was assumed to be a Ree-Eyring non-Newtonian fluid. The time-dependent numerical solutions were achieved instant after instant in each period of vibrations. The periodic error was checked at each end of the vibration period until the responses of pressure, film thickness and temperature were all periodic functions with the frequency of the roller's vibrations. At each instant, the pressure field was solved with a multi-grid method, the surface deformation was solved with a multi-level multi-integration technique, and the temperature field was solved with a finite difference scheme through a sweeping process. It was shown that the normal vibration dominated the EHL characteristics and could be either strengthened or weakened slightly depending on the phase of the tangential vibration. It was also found that the vibration of the roller could produce transient surface dimples within the contact conjunction.