Effect of contact geometry on lubricant replenishment in grease lubricated rolling contacts.

The contact geometries encountered in rolling element-outer race or inner race contacts in real bearings are not involved in conventional ball-on-flat disc configurations. However, the underlying lubricant replenishment mechanism induced by the contact conformity plays a significant role in maintaining a long-term operation of the rolling bearings. To reveal those replenishment mechanisms, the traditional flat disc is replaced by a grooved disc to reproduce the contact geometries. Additionally, a ball support structure consisting of dual arc-shaped rollers is employed to simulate the ball-inner race contact, aiming to explore the contributions of grease distributions to replenishment. The results show that the film thickness gradually diminishes to severe starvation states in the traditional contact configuration, while the lubrication states are efficiently improved as the ball-grooved or ball-arc shaped contact configuration is introduced, confirming the replenishment efficiency. The enhanced lubricant replenishment behaviors can be attributed to the high-strength shear exerted on the grease both at the inlet region and within the contacts where micro-slip occurs, as well as the surface tension and capillary force-induced lubricant replenishment. The findings of this study contribute to a comprehensive understanding of grease lubrication and replenishment in real bearings. [ABSTRACT FROM AUTHOR]