Computing hydrodynamic pressure in mixed lubrication by modified Reynolds equation

Abstract

Nowadays, even with the available computing power, complete deterministic solutions of large or dynamically loaded bearings are not possible in acceptable amounts of computing time. Therefore, in order to model mixed lubrication conditions, the Reynolds equation is modified by the introduction of flow factors that take into account the roughness effects. Patir and Cheng proposed the most known model. In their model, flow factors are obtained from the statistical parameters of the surface roughness. The flow factors can also be computed from deterministic calculation on a sample of the studied surface or by using the homogenization technique on the same surface sample. In this article, three approaches are compared. Moreover, the influence of the surface deformation due to asperity contact over the flow factors is investigated.

Investigations on transitions of lubrication states for water lubricated bearing. Part I: determination of friction coefficients and film thickness ratios

“…Where, f asp is the friction coefficient due to micro-asperities contacts effect. The calculation method and procedure can be attained in reference (Kraker et al ., 2007; Fatu et al ., 2012). f fluid is the friction coefficient due to “viscous effect”, i.e.…”

An assessment of the effect of surface topography on coefficient of friction for lubricated non-conformal contacts

“…Apart from the Patir and Cheng (Patir and Cheng, 1978) average flow model, the homogenization method (Bayada and Chambat, 1988) which also is a kind of averaging method, have received much attention due to its accurate averaging results and applicability for arbitrary oriented rough surfaces (Rom et al, 2021). Different forms of the homogenized Reynold's equations were derived to study both the stationary and transient lubricated contact problems (Bayada and Faure, 1989;Bayada et al, 2005;Almqvist and Dasht, 2006;Almqvist et al, 2007;Almqvist et al, 2011;Almqvist et al, 2012;Fatu et al, 2012). Unlike the Patir and Cheng average flow model (Patir and Cheng, 1978), the method of homogenization is not commonly used in tribology (Rom et al, 2021).…”

The Effect of Surface Defect on EHL Point Contact

“…It is generally accepted that the effective lubrication in machine can reduce the friction and wear of machine, which can be able to ensure machine for long life and prevent mechanical failure [1][2]. Two lubricated surfaces moving relatively were separated completely by means of the viscous fluid lubrication film emerged by the relative velocity of the surfaces, the fluid film bearing the external load and forming good lubrication, could avoid the wear and tear caused by hard abrasive wear and metal surface welding, allowed the friction generating in fluid film to bring about friction reducing [3][4][5][6]. In elastic hydrodynamic lubrication , surface geometric shape, surface topography and surface defect would affect surface lubrication greatly.…”