Effect of single- and multi-scale surface patterns on the frictional performance of journal bearings A numerical study

The present study aims at numerically predicting the frictional performance of journal bearings with single- and multi-scale surface patterns considering the real 3D surface topographies after wearing-in in mixed-elastohydrodynamic (mixed-EHL) simulations using a multi-body simulation (MBS) environment. For this purpose, the extended Reynolds equation with flow factors according to Patir and Cheng has been combined with a deterministic asperity contact model, which can be further utilized in the design process to optimize the tribological response of engineering systems. For all patterned surfaces, a shift to smaller rotational speeds in the transition from mixed to hydrodynamic lubrication with a notably reduced coefficient of friction has been demonstrated. The largest frictional improvement (- 80%) has been achieved with single-scale surface patterns fabricated by direct laser interference patterning.