THE ELASTOHYDROSTATIC ANALYSIS OF COMPENSATED THRUST BEARINGS

Abstract

It has been realised since long that the perfor-mance characteristics of lubricated contacts may get effected by elastic deformations occurring in contacting surfaces. However, to obviate mathematical complexity involved in the theoretical analysis,. the elastic consi-deration were not accounted in computing the performance of the lubricated contact. Most studies [1,2] considering elastic deformation of lubricated surfaces were confined to heavily loaded contacts such as gear teeth ,cams and rolling element bearings. Few studies [3,4,5,6,7] determining the effect of deformations on the performance characteristics of fluid film bearings are available in literature. Experi- 6,7 mental and theoretical investigations 8-] concerning slider and journal bearings demonstrated the considerable effect of bearing deformation on pressure distribution load capacity etc. The investigations commonly available in the field O f hydrostatic bearings have disregarded the effect of deformation on the performance characteristics. For rigid hydrostatic bearing system, the performance characteristics have been reported in reference [8,9,10,11]. Loeb and Ripple [8] designed the hydrostatic bearing for 2 its optimum performance and determined the effect of r^cess size , on pressure, flow and power requirements for different hydrostatic bearing configuration. The analysis attempted by Morsi [9] reveals that the stiffness of hydrostatic bearing is a function of bearing shape, bearing dimension, magnitude of applied load, film thickness and type of compensator. Adams and Shapiro [10 ] studied the hydrostatic squeeze film characteristics and gave design curves for various typeo of compensated bearings. Ghai, R. C. [11] analysed the static and dynamic characteristics of hydrostatic journal bearings using finite element method. Scant literature on the effects of elastic defor-mation of various elements on performance characteristics of hydrostatic bearing, is available [12,13]. Castelli, Rightthire, and Fuller [13] carried out analytical and experimental investigation on the effects of compliance on the performance of circular hydrostatic thrust bearings. The bearing runner was taken to be deformable while bearing pad was assumed to be rigid. They demonstrated that the compliant bearing has a superior load carrying capacity as compared to rigid surface bearings. Similar studies by Dowson and Taylor [12] demons-trated that the compliant effect is beneficial to improve the performance of hydrostatic thrust bearings. Rightmire, Castelli and Fuller [14] carried out experi-mental investigation of compliant surface tilting shoe, hydrodynamic thrust pad bearing and observed that the bearing k, with a. compliant pad has more load carrying capacity than rigid pad bearing. Further the bearing with a compliant pad are advantageous in accepting dimensional tolerances and surfaces finish. So their fabrication cost would be low.......