Effects of solid viscoelasticity on elastohydrodynamic lubrication of point contacts

Dry and lubricated highly deformed contacts appear in engineering, physics, and bio-(fluid)mechanics, with increasingly many applications where the soft materials can exhibit viscoelastic behaviour. In this work, the viscoelastic solid lubricated point contact problem has been studied theoretically and experimentally. An efficient visco-elastohydrodynamic lubrication (VEHL) numerical algorithm has been developed by implementing a novel viscoelastic deformation equation. The relevant dimensionless parameters of the VEHL problem are identified and a parameter study is presented showing the effect of solid viscoelasticy on the pressure and film thickness in the conjunction. In addition experimental results are presented for film thickness measurements in configurations of a PMMA ball rolling against a glass disc, and a steel ball rolling against a glass disc using optical interferometry. Finally the scaling of the pressure and film profiles in the inlet and outlet regions to the contact have been studied, investigating self similarity of the pressure and film solution in these regions. The results presented provide a good framework for the understanding and interpretation of viscoelastic solid effects on the film and pressure behavior in highly deformed (soft) lubricated contacts.