Experimental study on lubrication regime variation in point contacts

The change between elastohydrodynamic lubrication (EHL) and hydrodynamic lubrication (HL) under a wide range of entrainment speeds and applied loads was studied using an optical EHL apparatus. A log-log scale linear relationship was demonstrated in the two lubrication regions between the film thickness and the entrainment speed (or load). A transition region can be clearly discerned between these two regions in which the film thickness no longer bears a linear relationship with the entrainment speed (or load). It is shown that a piezoviscous effect can be distinguished in the HL region by the speed exponent or the load exponent, and that relative sliding has a significant influence on the transition region.