The Influence of Longitudinal Roughness in Thin-Film, Mixed Elastohydrodynamic Lubrication

The spacer layer imaging method (SLIM) has been used to investigate the influence of longitudinal asperities, with their major axis along the direction of lubricant entrainment, on the thickness and shape of thin, elastohydrodynamic (EHD) films. The effects of entrainment speed and rolling-sliding conditions on film thickness are shown for two different asperity heights. The morphology of the films formed and their thicknesses are used to discuss the influence of longitudinal roughness on film-forming capability and pressure perturbation within EHD contacts. Direct comparisons between the measurements and predictions of a theoretical model reveal the combined effects of longitudinal roughness and extremely low lambda ratios on surface compliance and, thus, EHL film formation. It is shown that the micro-EHL film thickness can be calculated by applying theoretical film thickness regression equations for smooth EHD contacts to the elongated, elliptical contacts formed by longitudinal ridges in thin-film conditions. Presented at the STLE Annual Meeting, in Las Vegas, Nevada, May 15-19, 2005 Review led by Liming Chang

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