NUMERICAL-SIMULATION OF A BALL IMPACTING AND REBOUNDING A LUBRICATED SURFACE

The case of a ball bouncing on a flat surface covered by a thin lubric ant layer is analyzed theoretically. Both impact and rebound are studi ed. A Newtonian lubricant and perfect elastic solids are assumed. As l ong as the ball approaches the flat surface the pressure in the contac t increases and a lubricant entrapment is formed at the center of the contact. When the ball begins to leave the surface, cavitation occurs. At the periphery of the contact a pressure spike is formed. Just befo re the ball leaves the lubricated surface, very high pressure values a rise at and near the contact center. These results are compared with t he case of nonlubricated impact. It is found that the pressure in the contact at lubricated impact is higher than in the case of dry impact. Due to the elastic and damping properties of the lubricant film and t he impacting surfaces, a time delay is observed between the time of ma ximum impact force and minimum film thickness. Comparing the theoretic al results with experimental results, presented by other authors, show s goad correlations.