The effects of couple stress lubricants and surface roughness on squeeze EHL motion between porous medium layer and elastic ball

Abstract

This paper investigated the effects of porous media layer (PML) and couple stress (CS) lubricants at pure squeeze action in an isothermal elastohydrodynamic lubrication (EHL) point contact with surface roughness (SRN) under constant load condition. The modified transient stochastic Reynolds equation was derived in polar coordinates by means of the Christensen’s stochastic theory and the Stokes’s CS fluid theory. The Gauss-Seidel method (GSM) and the finite difference method (FDM) were both used to solve simultaneously modified transient stochastic Reynolds, force equilibrium, elasticity deformation, and rheology equations. The simulation results revealed that the greater permeability ( K ) and porous layer thickness (Φ) are, the smaller central pressures ( P c ) are, and the smaller film thicknesses ( H ) are. The times required for achieving maximum central pressures (Pc max ) decrease with increasing K and Φ. Due to squeeze and elastic deformation effects, the slope values of central velocity ( V c ) change from negative to positive. The magnitude of V c and V min decreased with decreasing K and Φ. The Hcmin of circular type RN are greater than that of radial type RN. The Pc max of radial type RN are slightly greater than that of circular type RN.