Surface Roughness Effects on the Load Carrying Capacity of Very Thin Compressible Lubricating Films

Abstract

The effect of surface roughness on load carrying capacity of very low clearance gas bearings is analyzed. A model lubrication equation appropriate for high bearing number, finite width films is first derived. Then, by obtaining exact solutions to several simple geometry bearings, the “closure problem” or statistical relationship of pressure and spacing is revealed. The lubrication equation is then ensamble averaged and solved for several test cases. The seemingly subtle differences in ensamble averaging the transverse terms in the lubrication equation are compared for the current theory and a previous method and are shown to produce vast differences in load carrying capacity. The current method is expected to be the correct approach since it is based on a generalization of exact solutions.