The investigations of asperity peaks and surface roughness on transient squeeze elastohydrodynamic lubrication

Abstract The effects of asperity peak contact pressure and surface roughness (SRN) on pure squeeze elastohydrodynamic lubrication (EHL) motion of circular contacts are investigated for fixed load by using Gauss-Seidel iteration method (GSIM) and finite difference method (FDM). The transient pressure, asperity peak contact pressure, elastic deformation, and film thickness during the pure squeeze process under distinct operating conditions in EHL regime are studied. The results indicate that the differences of the pressure and film thickness between SRNEHL model and EHL model are apparent in final stage due to elastic asperity peak contact. The asperity peak contact pressure will affect hydrodynamic pressure for fixed load, so the hydrodynamic pressure with roughness surface is smaller than that without roughness surface especially around the Hertzian contact (X=1) edge. These phenomena result in different changes in total pressure in different areas. For the contact region, the film thickness of smooth type (ST) is greater than those of circular roughness type (CRT), but this phenomenon reverses near X=1. The larger the C value, the earlier the asperity peak contact effect. Therefore, the greater the C values, the greater the asperity peak contact pressure, and the smaller the hydrodynamic pressure. The asperity peak contact effect significant changes many phenomena at contact region in squeezing final stage.