Effects of lubricant rheology and impact speed on EHL film thickness at pure squeeze action

A squeeze film action is an essential phenomenon in elastohydrodynamically lubricated conjunctions subjected to impact loading or sudden halting of motion and affects both film thickness and friction. This study presents experimental results of film thickness behaviour of lubricant entrapment under diverse conditions including initial impact gaps, initial approaching speeds, loading speeds and variety of lubricants during introductory part of impact loading. The results are compared with recent theoretical solution. It is shown that the entrapped film shape directly depends on loading speed and the central film thickness is mainly determined by the approaching speed and lubricant viscosity and can be approximated by power law where the influence of impact times/speeds can be estimated from basic rheological properties of lubricants.