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 throughout the high-pressure conjunction at regular intervals while the running conditions are steady. This study shows that such a situation can be associated with a type of stick-slip phenomenon in which adherence at the wall is periodically lost. A simple time-dependent model is developed to validate this concept. The model extends the consideration of interfacial slip previously proposed and accounts for a periodic variation in slip with time. The results reveal that such a condition effectively allows trains of single dimples to move throughout the conjunction. A refined modelling of the conditions at the wall/lubricant interface is, however, required in the future if a better understanding of the conditions which trigger such instabilities is to be obtained.