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Advances in Tribology
Volume 2012, Article ID 296464, 7 pages
http://dx.doi.org/10.1155/2012/296464
Research Article

Mixed and Fluid Film Lubrication Characteristics of Worn Journal Bearings

College of Manufacturing and Design Technology, Muroran Institute of Technology, 27-1, Mizumoto-cho, Hokkaido, Muroran 050-8585, Japan

Received 30 June 2011; Accepted 8 December 2011

Academic Editor: Gun Hee Jang

Copyright © 2012 Toshiharu Kazama and Yukihito Narita. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The mixed and fluid film lubrication characteristics of plain journal bearings with shape changed by wear are numerically examined. A mixed lubrication model that employs both of the asperity-contact mechanism proposed by Greenwood and Williamson and the average flow model proposed by Patir and Cheng includes the effects of adsorbed film and elastic deformation is applied. Considering roughness interaction, the effects of the dent depth and operating conditions on the loci of the journal center, the asperity-contact and hydrodynamic fluid pressures, friction, and leakage are discussed. The following conclusions are drawn. In the mixed lubrication regime, the dent of the bearing noticeably influences the contact and fluid pressures. For smaller dents, the contact pressure and frictional coefficient reduce. In mixed and fluid film lubrication regimes, the pressure and coefficient increase for larger dents. Furthermore, as the dent increases and the Sommerfeld number decreases, the flow rate continuously increases.