Transient concentrated finite line roller-to-race contact under combined entraining, tilting and squeeze film motions

This paper presents the results of an analysis of the lubricated roller-to-raceway contact dynamics under transient conditions. This is caused by the load distribution in a bearing as a roller traverses from an unloaded to a highly loaded region. The roller is subjected to combined rolling and tilting motions due to the transient nature of the applied contact load. Correspondingly, the lubricated contact undergoes combined steady-state entraining motion and cyclic squeeze film action, with a steady total bearing load assumed. The results show that the roller tilts from side to side as it moves from the unloaded into the loaded region, and in the presence of a diminishing gap suffers higher pressures. In the meantime the regime of lubrication alters from iso-viscous rigid to full elastohydrodynamic. A major finding of this paper is regarding the emergence of a squeeze cave region in the contact, prevailing under a regime of lubrication different from the overall contact conditions, as indicated by the regimes of lubrication charts. The significance of this finding is that under isothermal conditions the kinematics of the contact and regional lubricant behaviour can lead to the formation of a dimple, even without the recently proposed thermal wedging effect.