Effects of Viscoelasticity of Greases on Lubrication

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The object of this project is to establish an analytical procedure for fluid film lubrication with greases, because a grease is used in practice due to easy lubrication system as compared with that by other lubricants such as oil.A rheology equation supposed in this project, which consists of one slider and two nonlinear dashpots and two non-linear springs is investigated experimentally for the grease.Modified Reynolds equations are derived employing the rheology equation mentioned above. The equations are different types whether the stress of grease in lubricating film is greater than yield stress or not, that is core occurs or not.By an application of the modified Reynolds equations to the journal bearings, the bearing performance is clarified theoretically. Bingham characteristics effects on the core formations and viscoelastic behavior influences on the phase lag of pressure for squeeze action. The theoretical results are compared with the experiments of squeeze bearings using greases as a lubricant.