Numerical solution of dry friction in point contact using the unified Reynolds method combined with rarefied gas effect

Abstract

Dry friction problems are widespread in engineering applications. However, the current research on the contact pressure between interfaces mainly relies on static contact mechanics solutions, neglecting the influence of the contact pressure generated by the gases in the environment. In this paper, the ambient gas is considered as a lubricant with lubricating effects. Drawing inspiration from hydrodynamic lubrication methods, a unified mixed lubrication equation for dry friction problems is developed, taking into account the influence of gas rarefaction effects. This study computes the dry friction contact pressure under different winding speeds and loads. The advantage of this method lies in its ability to automatically distinguish between the contact and noncontact regions during the calculation process, enabling the determination of the contact pressure over the entire contact area. The computational results demonstrate that at low entrainment velocities, there is minimal deviation in contact pressure and contact area compared to Hertzian contact. However, as the entrainment velocity increases, the actual pressure-bearing area enlarges compared to static contact, and there is a smooth transition of pressure at the contact edge, which cannot be obtained from static contact analysis. Finally, the numerical solution of the contact pressure when the sliding speed spans several orders of magnitude is given, and the calculation results show that the numerical model has good robustness. This numerical approach offers valuable insights for guiding the design of air bearings in practical applications.