Lubricant additives effects on the hydrodynamic lubrication of misaligned conical–cylindrical bearings

Abstract

Conical-cylindrical bearings are used in electrohydraulic servo systems to improve the control accuracy, eliminate the static friction and increase the normal load-carrying capacity. A non-Newtonian rheological model to investigate theoretically the effects of lubricant additives on the performance of misaligned conical-cylindrical bearings is proposed in this study. In this model, the non-Newtonian behaviour resulting from blending the lubricant with polymer additives is simulated by Stokes couple stress fluid model. The formed boundary layer at the bearing surface is described through the use of a hypothetical porous medium layer that adheres to the bearing surface. The Brinkman-extended Darcy equations are utilised to model the flow in the porous region. A stress jump boundary condition is applied at the porous media/fluid film interface. The misalignment of the cylinder rod is also considered. A modified form of the Reynolds equation is derived and solved numerically using a finite difference scheme. The effects of bearing geometry and non-Newtonian behaviour of the lubricant on the steadystate performance characteristics such as pressure distribution, load-carrying capacity and coefficient of friction are presented and discussed. The results showed that lubricant additives significantly increase the load-carrying capacity and reduce the coefficient of friction as compared to the Newtonian lubricants. Furthermore, the misalignment of the piston rod has significant effects on the performance of conical-cylindrical bearings. Copyright

Piezo-Viscous Dependency and Surface Roughness Effects on the Squeeze Film Characteristics of Non-Newtonian Micropolar Fluid in Conical Bearings

“…They found that the effect of micropolar lubricant enhances the performance of the bearing as compared to the Newtonian lubricant. Elsharkawy [11] studied the lubricant additives' effects on the hydrodynamic lubrication of misaligned conical cylindrical bearings.…”

Squeeze film characteristics of conical bearings with combined effects of piezo-viscous dependency and non-Newtonian couple stresses

“…Lubricant additives' effects on the hydrodynamic lubrication of misaligned conical cylindrical bearings were analysed by Elsharkawy. 25 He observed that, lubricant additives significantly increase the load carrying capacity and reduce the coefficient of friction as compared to the Newtonian lubricants. It is reported that the effect of viscosity pressure dependency (VPD) increases the squeeze film pressure, load carrying capacity and the squeeze time.…”

“…Sharma and Rajput 23, 24 studied lubrication performance of four-locked capillary compensated conical hybrid journal bearing and externally pressurised multirecess conical hybrid journal bearing system using micropolar lubricant and found that, the effect of micropolar lubricant enhances the performance of the bearing as compared to the Newtonian lubricant. Lubricant additives’ effects on the hydrodynamic lubrication of misaligned conical cylindrical bearings were analysed by Elsharkawy 25 . He observed that, lubricant additives significantly increase the load carrying capacity and reduce the coefficient of friction as compared to the Newtonian lubricants.…”

Hydrogenated styrene–isoprene–butadiene rubber: optimisation of hydrogenation conditions and performance evaluation as viscosity index improver

“…Hydrogenation offers a potential and useful method for optimising and altering the physical and mechanical properties of macromolecules and for producing new materials with improved properties . Several hydrogenation methods were used to saturate polymers based on the stoichiometric reaction of heterogeneous or homogeneous catalytic hydrogenation with gaseous H 2 . Subsequently, non‐organometallic catalytic hydrogenation reactions were studied .…”