Load distribution analysis of journal bearings operating under mixed lubrication conditions

When the lubricant film that separates two loaded members becomes thin enough, the asperities on the surfaces begin to interfere. Hydrodynamic journal bearings invariably experience this phenomenon during starting and stopping which is called mixed lubrication. In this case, a part of the applied load is carried by the hydrodynamic action of the fluid film and the remainder through asperity contacts. The part of the load supported by the asperities is significant in that it determines the wear life of the bearing to a large extent. In this work, analytical procedures for the determination of these two components of load based on statistical nature of surface topography have been developed. An algorithm for the estimation of limiting load from wear consideration has been presented. The effect of variation of typical surface topography parameters which undergo change during wear process viz. standard deviation of profile sum, combined radius of curvature of asperities, on hydrodynamic and asperity load supporting capabilities and true area of contact has been discussed. The computations have been illustrated with experimental data.