Post-impact squeeze-out behavior of oils with different pressure-dependent rheological properties

The rapid approach of surfaces significantly increases pressure and viscosity of lubrication oil, trapping it in a dimple at the contact zone that requires time to be squeezed out. In this study, a measuring system was developed that utilized a ball-disk impact device and light interference technology to investigate the post-impact squeeze -out behavior of oils. Dimple shape evolution varied depending on the pressure-dependent rheological properties of the oils. Specifically, higher pressure-viscosity coefficients resulted in greater reduction in dimple radius, whereas lower pressure-viscosity coefficients led to quicker collapse in dimple height, providing a qualitative criterion for comparing pressure-dependent rheological properties of oils. Additionally, effect of initial dimple height and external load on the squeeze-out behavior were investigated.