INFULENCE OF WEAR ON THE PERFORMANCE OF CAPILLARY COMPENSTED HYDROSTATIC/HYBRID JOURNAL BEARING

Abstract

In recent times Hydrostatic journal bearings have received considerable amount of attention by the researchers on account of their excellent performance as compared to other class of bearings. The Hydrostatic/Hybrid journal bearing systems have been widely used in number of applications such as rolling mills, machine tools, optical telescopes, medical equipment and turbines in power plants etc. due to their ability to support heavy loads at low speeds, low frictional characteristics and good vibration damping characteristics. Generally, in the partial lubrication regime, rubbing of asperities causes wear. The wear mechanisms by which the asperity material is removed, varies considerably with the asperity geometry, surface film shear stress, material property and lubricant chemistry. For example, the asperities with random geometry generally results in abrasive wear in which material is removed by ploughing or cutting. The field of wear is very broad; the present study is basically concerned with the wear which occurs due to frequent start/stop operations. The performance of hydrostatic/hybrid journal bearing systems gets affected by number of parameters such as type of restrictor, bearing liner flexibility and mode of operation of bearing (hydrostatic/hybrid) etc. It also depends on the load arrangement; therefore the present work is aimed to study the effect of wear on the performance of bearing by considering the various effects. When the journal bearing system is subjected to heavy loads, the bearing linear deforms under high fluid film pressures. This in turn modifies the fluid film thickness profile and ultimately changes the bearing performance. For computing the bearing performance characteristics, the Reynolds equation for the flow of lubricant in the clearance space with equation of flow through restrictor as a constraint has been solved using appropriate boundary conditions. The flow field solution domains has been discretized using 4-noded isoparametric elements. The static and dynamic performance characteristics are presented for various effects and conclusions are drawn.