Performance analysis of rough surface hybrid thrust bearing with elliptical dimples

Surface roughness is inherent to all machining processes. Therefore, even a high precision machining process renders micro-roughness to some extent on the surface of conventional materials. The asperities height of many rough engineering surfaces follows Gaussian distribution. The surface roughness on the bearing surface may significantly affect the bearing performance. Surface texturing is emerging as a new technique to improve the tribological behavior of the mating surfaces. Usually dimensions/height of micro-roughness is of order of the depth of surface textures in fluid film bearings. Neglecting micro-roughness while numerically simulating a textured surface bearing may generate inaccurate bearing performance data. In presented work, finite element simulation of textured surface hybrid thrust bearings has been performed. Surface texture is provided over thrust pad in the form of regular arrays of elliptical dimples. A parametric optimization is carried out to determine optimum attributes of elliptical dimple (axis, depth, texture length and orientation) so that the load-carrying capacity and fluid film stiffness should be maximized and film frictional power losses should be minimized. Use of textured surface (with optimum elliptical dimple attributes) results into a significant enhancement in load-carrying capacity (91.3%), film stiffness coefficient (+98.8%) and reduction in frictional power losses (−48.3%). It is also observed that elliptical dimple and micro-roughness (transverse orientation) generate synergistic effects in further enhancing the load-carrying capacity (+101.4%) and film stiffness coefficient (+112%) of the bearing.