Mixed-lubrication study of journal bearing conformal contacts
01 Dec 1996-
TL;DR: In this article, the average Reynolds equation derived by Patir and Cheng was utilized in the lubrication analysis of finite journal bearings operating with large eccentricity ratios to better understand the mixed lubrication phenomena in conformal contacts.
Abstract: Numerical analyses of finite journal bearings operating with large eccentricity ratios were conducted to better understand the mixed lubrication phenomena in conformal contacts. The average Reynolds equation derived by Patir and Cheng was utilized in the lubrication analysis. The influence function, calculated numerically using the finite element method, was employed to compute the bearing deformation. The effects of bearing surface roughness were incorporated in the present analysis for the calculations of the asperity contact pressure and the asperity contact area. The numerical solutions of the hydrodynamic and asperity contact pressures, lubricant film thickness, and asperity contact area were evaluated based on a simulated bearing-journal geometry. The calculations revealed that the asperity contact pressure may vary significantly along both the width and the circumferential directions. It was also shown that the asperity contacts and the lubricant film thickness were strongly dependent on the bearing width, asperity orientation, and operating conditions.
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TL;DR: In this paper, the authors report the results of a series of experiments performed on a journal bearing together with a theoretical prediction of the Stribeck-type behavior for various loads and oil temperatures.
Abstract: The Stribeck curve plays an important role in identifying boundary, mixed, elastohydrodynamic, and hydrodynamic lubrication regimes. Recent advances in elastohydrodynamic lubrication together with rough surface interaction have made it possible to develop a methodology for predicting the trend of the Stribeck curve. In this paper; we report the results of a series of experiments performed on a journal bearing together with a theoretical prediction of the Stribeck-type behavior. Various loads and oil temperatures are considered. The comparison between the experimental results with a mixed elastohydrodynamic lubrication model for line contacts is indicative of good agreement.
212 citations
TL;DR: In this article, a mixed elastohydrodynamic lubrication (EHL) model for finite length elastic journal bearings is described and the finite element method is employed to discretise the coupled system of 2D-3D Reynolds-structure equations and to compute Stribeck curves at constant load.
76 citations
01 Jan 2000
TL;DR: A deterministic mixed lubrication model, governing the interface between a movingsmooth rigid surface and a stationary rough elastic surface, has been developed in this paper, where both thenormal and shear deformations of the elastic surface are considered, as well as interasperity cavitation.
Abstract: A deterministic mixed lubrication model, governing the interface between a movingsmooth rigid surface and a stationary rough elastic surface, has been developed. Both thenormal and shear deformations of the elastic surface are considered, as well as interas-perity cavitation. Utilizing an analogy between the hydrodynamic lubrication (withcavitation) problem and the asperity contact problem, a generalized computationalformulation is derived and a unique solution scheme constructed to solve these seeminglydifferent problems. The model has been applied to the rotary lip seal, and used to predictthe performance characteristics over a range of shaft speeds.
74 citations
TL;DR: The use of three typical convolutions, two convolution theorems, influence coefficients, and shape functions, as well as the influence of domain size are discussed.
71 citations
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1,882 citations
01 Jun 1970
TL;DR: In this article, the authors give a general theory of contact between two rough plane surfaces and show that the important results of the previous models are unaffected: in particular, the load and the area of contact remain almost proportional, independently of the detailed mechanical and geometrical properties of the asperities.
Abstract: Most models of surface contact consider the surface roughness to be on one of the contacting surfaces only. The authors give a general theory of contact between two rough plane surfaces. They show that the important results of the previous models are unaffected: in particular, the load and the area of contact remain almost proportional, independently of the detailed mechanical and geometrical properties of the asperities. Further, a single-rough-surface model can always be found which will predict the same laws as a given two-rough-surface model, although the required model may be unrealistic. It does not seem possible to deduce the asperity shape or deformation mode from the load-compliance curve.
1,435 citations
TL;DR: In this paper, the elastic contact of an isotropically rough surface with a plane is treated by approximating the summits of a random process model by paraboloids with the same principal curvatures and applying the classical Hertzian solution for their deformation.
710 citations
Abstract: The analysis of an isothermal elastohydrodynamic lubrication (EHL) point contact was evaluated numerically. This required the simultaneous solution of the elasticity and Reynolds equations. In the elasticity analysis the contact zone is divided into equal rectangular areas and it is assumed that a uniform pressure is applied over each element. In the numerical analysis of the Reynolds' equation a phi analysis where phi is equal to the pressure times the film thickness to the 3/2 power is used to help the relaxation process. The EHL point contact analysis is applicable for the entire range of elliptical parameters and is valid for any combination of rolling and sliding within the contact.
393 citations
TL;DR: In this article, the contact of random surfaces is discussed in terms of a general theory of such surfaces previously described by Whitehouse and Archard, and the derived results are compared with the earlier work of Greenwood and Williamson.
Abstract: The contact of random surfaces is discussed in terms of a general theory of such surfaces previously described by Whitehouse and Archard, and the derived results are compared with the earlier work of Greenwood and Williamson. The physical significance of the differences between the two theories are discussed; in particular, the influence of a distribution of asperity curvatures is revealed. It is suggested that the simple model of Greenwood and Williamson can underestimate both the pressures at the true areas of contact and the probability of plastic flow.
230 citations