In this paper, a theoretical study of the combined effects of surface roughness and the variation of viscosity with pressure on the squeeze film lubrication between sphere and a flat plate is presented. Based on the Christensen’s stochastic theory for the hydrodynamic lubrication of rough surfaces, two types of one-dimensional surface roughness (radial and azimutal) patterns are considered. The generalized averaged Reynold’s equation for Stokes couple stress fluids accounting for the pressure dependent viscosity is mathematically derived for the problem under consideration. The standard perturbation technique is used to solve the averaged nonlinear Reynold’s equation and an approximate analytical solution for the fluid film mean pressure is obtained for the two types of one-dimensional roughness patterns. It is found that, the effects of couple stresses and pressure dependent viscosity variation are to improve the squeeze film characteristics.

Theoretical analysis of the effect of Piezo-viscous dependency and couple stress on squeeze film lubrication between parallel stepped plates is presented in this paper. According to the Stokes microcontinuum theory of couple stress fluids, the modified Reynold"s equation is derived by considering viscosity variation along the film thickness. The standard perturbation technique is used to solve the non-linear Reynolds equation and an approximate analytical solution for the film pressure is obtained. It is found that, the effect of couple stresses and pressure dependent viscosity variation is to increase the load carrying capacity and to lengthen the squeeze film time.