Effects of solid body temperature on the non-Newtonian thermal elastohydrodynamic lubrication behaviour in point contacts

Abstract

In order to investigate the influence of body temperature of contact solids on the lubrication performance of machine components such as gears and roll-bearings, full numerical solution for the non-Newtonian thermal elastohydrodynamic lubrication (EHL) problem in point contacts has been achieved, assuming that the body temperature is different from the temperature of the supplied lubricating oil. The Ree—Eyring rheology model has been used to describe the non-Newtonian behaviour of the lubricant. The effects of the body temperature, the slide—roll ratio, and the velocity parameter have been discussed. The results for the body temperature being higher or lower than the temperature of the supplied oil have been compared with that of the conventional thermal EHL solution, where the temperature of the contact bodies and the temperature of the supplied oil are assumed to be the same. Results show that, if the entrainment velocity is not very high, the solid body temperature plays a dominant role in the EHL behaviour; however, the influence of body temperature decreases as the entrainment velocity increases. Comparisons between the non-Newtonian and Newtonian numerical results have been made under some operating conditions. It has been shown that, compared with the Newtonian solution, the non-Newtonian property of the lubricant can always lead to lower frictional coefficient and lower temperature, but has little effect on the film thickness, no matter the temperature of the contact bodies is lower than, equal to, or higher than that of the supplied oil.