Micro-geometry effects on the sliding friction transition in elastohydrodynamic lubrication

Abstract An engineering scheme is proposed to calculate the effects of deterministic micro-geometry in sliding friction for the transition between full-film elastohydrodynamic and boundary lubrication regimes. The method combines the concepts of micro-geometry deformation from lubricated and/or dry contact conditions. Pressures are calculated from the elasto-plastic displacements and the load sharing between lubricant and contacts is resolved iteratively in the classical way, i.e. flow balance. Thus, by varying the lubricant entrainment speed in the contact for known values of boundary and full-film friction coefficients, it is then possible to calculate the Stribeck curve. The scheme is semi-analytical and the use of fast Fourier techniques makes it attractive for engineering applications. Theoretical predictions are compared with numerical solutions from the literature and with in-house measurements for different surface topographies and the results are in reasonable agreement with the model.