Combined Surface Roughness Pattern and Non-Newtonian Effects on the Performance of Dynamically Loaded Journal Bearings

Abstract

The effects of three surface roughness patterns (purely circumferential, axial and isotropic) are investigated for an elliptically shaped journal bearing subjected to dynamic loading. The mass-conserving, finite element, scheme proposed by Kumar and Booker (1991) is used to model the cavitation. Moreover, a non-Newtonian model is included to account for shear thinning effects of the lubricant. The results show that the circumferential (microgrooved) surface pattern produces larger and more beneficial effects on bearing performance than do the other surface roughness patterns. Due to surface pattern effects, the maximum film pressure is found to decrease by as much as 12% and the minimum film thickness can increase by as much as 17%, depending on the bearing geometry, the loading and the asperity heights. Surface roughness patterns were found to have little effect on the flow rate and friction torque.