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Naduvinamani N.B.,Gulbarga University | Rajashekar M.,Government Pu College For Girls
Tribology - Materials, Surfaces and Interfaces | Year: 2011

In this paper, the effect of non-Newtonian couple stress fluids on the magnetohydrodynamic (MHD) squeeze film characteristics between a sphere and a plane surface is analysed. By taking into account the couple stresses due to the presence of microstructure additives in the lubricant and the magnetic effects due to the magnetisation of the couple stress fluid, the non-Newtonian couple stress MHD Reynolds type equation is derived. The numerical solutions for the MHD squeeze film characteristics are presented for various values of couple stress parameter, and magnetic Hartmann number. The results indicate that the influences of couple stresses and the magnetic effects on the squeeze film characteristics are significantly apparent. It is concluded that the MHD couple stress fluids have better lubricating qualities than the corresponding Newtonian case. © 2011 W. S. Maney & Son Ltd. Source


Bhujappa N.N.,Gulbarga University | Mareppa R.,Government Pu College For Girls
Tribology Online | Year: 2013

The theoretical analysis of rheological effects of Rabinowitsch fluid on the steady and dynamic characteristics of inclined stepped composite bearings is investigated. The Rabinowitsch fluid model is considered to account the pseudoplastic and dilatant nature of the lubricant due to the presence of additives. The perturbation technique is used to derive the modified Reynolds equation separately for both steady state and perturbed characteristics of the bearing. The closed form expressions for the bearing characteristics are obtained. By using these expressions, the performance characteristics of four different types of bearings such as stepped, plane inclined slider, composite tapered land and composite tapered concave bearings are determined. It is found that, the non-Newtonian behaviour of the Rabinowitsch fluid have a significant effect on bearing characteristics. Further, it is found that the existence of a critical value for profile parameter at which the dynamic stiffness coefficient attains maximum. Copyright © 2013 Japanese Society of Tribologists. Source


Rajashekar M.,Government Pu College For Girls | Kashinath B.,Government First Grade College
Advances in Tribology | Year: 2012

The combined effects of couple stress and surface roughness on the MHD squeeze-film lubrication between a sphere and a porous plane surface are analyzed, based upon the thin-film magnetohydrodynamic (MHD) theory. Using Stoke's theory to account for the couple stresses due to the microstructure additives and the Christensen's stochastic method developed for hydrodynamic lubrication of rough surfaces derives the stochastic MHD Reynolds-type equation. The expressions for the mean MHD squeeze-film pressure, mean load-carrying capacity, and mean squeeze-film time are obtained. The results indicate that the couple stress fluid in the film region enhances the mean MHD squeeze-film pressure, load-carrying capacity, and squeeze-film time. The effect of roughness parameter is to increase (decrease) the load-carrying capacity and lengthen the response time for azimuthal (radial) roughness patterns as compared to the smooth case. Also, the effect of porous parameter is to decrease the load-carrying capacity and increase the squeeze-film time as compared to the solid case. © 2012 M. Rajashekar and Biradar Kashinath. Source


Naduvinamani N.B.,Gulbarga University | Rajashekar M.,Government Pu College For Girls
Industrial Lubrication and Tribology | Year: 2014

Purpose - The purpose of this article is to analyse the effects of surface roughness on the magneto-hydrodynamic (MHD) squeeze-film characteristics between a sphere and a porous plane surface, which have not been studied so far. Design/methodology/approach - The analytical model takes into account the effect of porosity by assuming that the flow in the porous matrix obeys modified Darcy's law. The stochastic MHD Reynold's type equation is derived by using the Christensen's stochastic method developed for hydrodynamic lubrication of rough surfaces. Two types of one-dimensional surface roughness (radial and azimuthal) patterns are considered. Findings - The expressions for the mean MHD squeeze-film pressure and mean load-carrying capacity are obtained numerically. The results are shown graphically for selected representative parametric values. It is found that the response time increases significantly for the MHD case as compared to the corresponding non-conducting lubricants. The effect of roughness parameter is to increase/decrease the load-carrying capacity and the response time for azimuthal/radial roughness patterns as compared to the smooth case. Also, the effect of porous parameter is to decrease the load-carrying capacity and response time as compared to the solid case. Originality/value - In this paper, an attempt has been made to analyse the combined effects of surface roughness and permeability on the MHD squeeze-film characteristics between a sphere and a plane surface. Copyright © 2014 Emerald Group Publishing Limited. All rights reserved. Source


Naduvinamani N.B.,Gulbarga University | Rajashekar M.,Government Pu College For Girls | Kadadi A.K.,Gulbarga University | Kadadi A.K.,Government Pu College For Girls
Tribology International | Year: 2014

In this paper, a theoretical analysis on the squeeze film characteristics between circular stepped plates lubricated with Rabinowitsch fluid is presented. By using Rabinowitsch fluid model, the modified Reynolds type equation is derived to study the dilatant and pseudoplastic nature of the fluid in comparison with Newtonian fluid. The closed form solution is obtained by using perturbation method. According to the results obtained, the load-carrying capacity and squeeze film time increases for dilatant fluids as compared to the corresponding Newtonian fluids whereas the reverse trend is observed for pseudoplastic fluids. Further, it is observed that the response time decreases as the step height increases. © 2014 Elsevier Ltd. Source

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