Modeling and analysis of elastohydrodynamic lubrication of line contacts considering thermal and non-Newtonian effects

A high accurate and efficient thermal non-Newtonian simulator is constructed to study the lubricant behavior in an EHL line contact conjunction. The circular non-Newtonian constitutive equation is incorporated into the Reynolds equation to simulate the limiting shear strength of the lubricant. A conservative form of the end equation considers both effects of the limiting shear strength and the limiting viscous normal strength of the lubricant. New interface temperature rise equations are formulated to consider the effects of full two-dimensional heat flow in the bounding solids.;The solutions for the lubricant behavior in the inlet zone, the central contact zone, and the outlet zone are obtained simultaneously by using the complete fast approach (with the Newton-Raphson method), the control-volume finite difference approach (with the successive-overrelaxation-by-line method), and the embedding-interface-temperature-equations technique.;Temperature distribution, thermal degradation of lubricant, and thermal and non-Newtonian effects on film generation and traction reduction are then studied. Results show that the maximum temperature occurs in the inlet zone at low slide-to-roll ratios and occurs in the central contact zone at medium and high slide-to-roll ratios. As the diffusion time increases, the inlet zone temperature increases near the slower moving solid surface. Thermal degradation of the lubricant may be a problem when the conjunction operates at high speeds and high slide-to-roll ratios.;Results also show that the inlet zone shear thinning effect is negligible. Therefore, the non-Newtonian effect on film thickness reduction is unimportant. Instead, the inlet zone pressure and piezothickening determine the film-thickness-generation capability and the inlet zone thermal thinning reduces this capability. As the operation approaches the simple sliding condition, the film thickness decreases drastically because of the diffusion time effect on the increase of the inlet zone temperature.;In addition, shear skidding (a non-Newtonian effect) and thermal skidding (a thermal effect) are identified as the two traction reduction mechanisms. Shear skidding is more effective at high loads, but thermal skidding is more significant at high speeds.