The Effect of Slider Geometry on the Performance of a Powder Lubricated Bearing — Theoretical Considerations

Abstract

An existing one-dimensional analysis for powder lubrication was upgraded to a two-dimensional level, providing an analytical tool for predicting side leakage effects. Prediction of side leakage is crucial since it accounts for heat removal from the solid lubricated contact zone and provides a measure of the wear rate. Using the enhanced analysis, a parametric study was conducted of the effect of key bearing geometric design parameters (such as film thickness and pad aspect ratios) on pressure, powder flow, load and friction. The studies revealed that for a film thickness ratio Hr of approximately 2.4, high load-carrying capability, low coefficient of friction and moderate side leakage result. For the optimum Hr, studies of the effect of Breadth to Length ratio (B/L) revealed that decreasing B/L from two results in a broader pressure peak and hence increased load capability. Decreasing the B/L ratio also lowers both the coefficient of friction and the side flow. A companion paper, Ref. (9), dealing with the experimental part of the present program provides corroboration for the present approach. The combined analytical and test results offer a tentative explanation for the known phenomenon in “dry” friction studies where a change of orientation and thus B/L ratio of the tested specimen results in different values of the coefficient of friction. Presented at the 54th Annual Meeting Las Vegas, Nevada May 23–27, 1999