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ISSN Print: 2152-5102
ISSN Online: 2152-5110
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Model of Elastohydrodynamic Lubrication with Molecularly Thin Lubricating Films. Part II: Results for an Exemplary Lubrication
ABSTRACT
In Part I of this research [1] a hydrodynamic lubrication in smooth line contacts at isothermal and steady state conditions, where molecularly thin lubricating films occur, was theoretically analyzed. This paper is a subsequent part of this research representing the quantitative results for an exemplary lubrication obtained within mentioned theory. It is shown that the effect of the surface pressure on the lubricant mass flow through the contact is insufficient. Therefore, the surface pressure influences mainly the local lubricant film thickness, but has a negligible influence on global film thickness. The surface pressure can cause wavy lubricant film thickness distribution in Hertzian contact zone and local disappearance of the film due to the extremely high attracting surface pressures at a very low local lubricant film thickness what is leading to local adhesion of the contact surfaces. This reduces the load carrying capacity of lubrication because of the decrease of a minimal thickness of the lubricant film. When molecularly thin lubricating films occur, the effect of lubricant's property variation across the film also decreases its thickness and, consequently, reduces the load-carrying capacity of lubrication. For example, a non-Newtonian (shear) thinning effect due to the Eyring stress increases the lubricant film thickness and the load-carrying capacity of lubrication. At the same time, the effects of the flow factor θv, as well as the contact adhering layer, are negligible.
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