EFFECTS OF SURFACE FORCES ON SQUEEZE EHL MOTION BETWEEN ELASTIC BALL AND ELASTIC COATED SURFACE

Abstract

The effects of surface forces (SF) and coated layers (CL) on pure squeeze elastohydrodynamic lubrication (EHL) motion of circular contacts are explored under constant load condition by using the finite difference method (FDM) and the Gauss–Seidel iteration method. The transient pressure profiles, surface force, film shapes, and elastic deformation during the pure squeeze process under various operating conditions in the TFEHL regime are discussed. The simulation results reveal that the difference between SFEHL model and EHL model is apparent as the film thickness is thinner than 5 nm. The oscillation phenomena in pressure and film thickness come mainly from the action of solvation forces. At contact region, the greater elastic modulus and smaller coating thicknesses, the greater pressure distribution, and the smaller film thickness. The film thicknesses are found reverse at outside the contact zone. At the exit region, i.e. the minimum film thickness region, it is valid that the greater the elastic modulus and the smaller the coating thicknesses, the greater the solvation pressure distribution. The effects of surface forces become significant as the film thickness becomes thinner.