Friction of Textured Surfaces in EHL and Mixed Lubrication: Effect of the Groove Topography.

The influence of the groove topography, especially their top width and their orientation upon the friction in elastohydrodynamic lubrication (EHL) and mixed lubrication regimes was characterized by means of Stribeck curves. Friction levels with groove surfaces were linked to optical measurements of the film thickness distribution inside the contact and compared with data for a smooth surface. In EHL, results indicate no overall friction modification. Nonetheless in this regime, the local film thickness becomes, under a critical top width, lower than the smooth surface leading to a shift of the EHL/mixed regime transition. In mixed regime, the friction is much higher than the smooth surface and narrower tops cause more severe friction than wider one. If the orientation of the grooves does not modify significantly the friction, transverse grooves (perpendicular to the entrainment direction) enable the formation of local dimples in mixed regime, which locally increase the lubrication efficiency. [ABSTRACT FROM AUTHOR]