Observation of Kaneta's dimples in elastohydrodynamic lubrication contacts

The formation of Kaneta's dimples are investigated under different sliding conditions using a high-speed video camera. Of interest is the observation of an unstable regime in which trains of dimples are formed and propagate t hroughout the high-pressure conjunction at regular intervals while the runn ing conditions are steady. This study shows that such a situation can be as sociated with a type of stick-slip phenomenon in which adherence at the wal l is periodically lost. A simple time-dependent model is developed to valid ate this concept. The model extends the consideration of interfacial slip p reviously proposed and accounts for a periodic variation in slip with time. The results reveal that such a condition effectively allows trains of sing le dimples to move throughout the conjunction. A refined modelling of the c onditions at the wall/lubricant interface is, however, required in the futu re if a better understanding of the conditions which trigger such instabili ties is to be obtained.