The influence of lubrication on the dynamic behaviour of ball bearings

Investigation into the dynamic behaviour of rolling element bearings is motivated by the urge to reduce vibrations in rolling bearing applications. The dynamics of the bearing is governed by both the dynamics of its structural elements, i.e., the inner ring, the outer ring and the rolling elements, and the elastohydrodynamic lubricated (EHL) contacts connecting these structural elements. To investigate the effect of the lubricant on the dynamic behaviour of deep groove ball bearings, computational models have been developed for both the EHL problem and the structural dynamics problem. In the present study, the interaction between the structural elements is described by means of a non-linear spring-damper model which is based on numerical solutions of the full EHL contact problem. These relations have subsequently been adopted in the structural dynamics bearing model. Using these models, the shift of bearing eigenfrequencies as a result of lubrication is investigated and modal damping values for the preloaded bearing are estimated. It is suggested that the shift of the eigenfrequencies is mainly caused by contact angle variations.