On the Rheodynamics of Third-Body Composed of Rigid Particles in Contact: Part I – Theoretical Considerations

Heshmat, H. “On the Rheodynamics of Third-Body Composed of Rigid Particles in Contact:  Part I – Theoretical Considerations,” 53rd Annual Meeting of STLE, May 1998.

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 f 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 2 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 corroboratio 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. 


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