Fluid lubrication of soft surface layers

Abstract

The performance of a lubricated, elastomer lined bearing is dependent upon the surface deformations of the liner. This investigation is concerned with the prediction of influence co-efficients for rigidly backed, soft layers by the finite element method. These are applied in the pure-sliding, elastohydrodynamic lubrication problem, of a rotating rigid cylinder loaded against a thin elastic layer, which covers the plane surface of a rigid solid. Theoretical solutions showing the influence of elastic distortions upon friction, pressure and film shape are presented. These are supported by experiments upon the same type of bearing. Pressure measurements and the tangential force on the plane surface for layers of various thicknesses are recorded as obtained from two experimental rigs. The persistence of hydrodynamlc or boundary lubrication for a soft layer compared to a rigid plane, under conditions of low speed or low viscosity lubricant, is also illustrated by the friction measurements. The term "soft" refers throughout to materials of low-elastic modulus.