Elastohydrodynamic Film Thickness in Elliptical Contacts With Spinning and Rolling

In this paper, a theoretical model for the film thickness prediction of elastohydrodynamic lubrication of elliptical contacts with spinning and rolling/sliding motions is presented, in which 1) an effective ellipticity ratio k e is introduced to present the ellipse feature instead of the normal ellipticity ratio k in case of that the entraining velocity at the center of contact ellipse is at an angle with minor axis, 2) Roelands and Dowson-Higginson's equations are adopted to express the influence of pressure upon lubricant viscosity and density, 3) multilevel/multigrid techniques, with low complexity and good stability, are used for the purpose of reducing computing time in the complex numerical analysis. With this model the characteristics of film shape andpressure distribution of elastohydrodynamic lubrication ofelliptical concentrated contacts with spinning and rolling/sliding were discussed. The results showed that the spinning motion has significant influence on the film shape and pressure distribution. Based on a large number ofnumerical results of elastohydrodynamic lubrication analysis of elliptical concentrated contacts with spinning and rolling/sliding, new expressions for the minimum and central film thickness prediction were regressed. Their accuracy was analyzed by comparisons with numerical results of an evaluation set and others' expressions underpure rolling and/or sliding condition. The comparisons showed that the two new expressions have satisfactory accuracy and potential application to engineering analysis and design.

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