Understanding topographic dependence of friction with micro- and nano-grooved surfaces

The work reported in this paper aims at understanding sliding friction anisotropy at the nano-, micro-, and macroscales with respect to surface asperity orientation and exploring the mechanisms behind this phenomenon. Experiments were conducted by probing surfaces with grooves parallel or perpendicular to the direction of relative motion. Continuum mechanics analyses with the FEM and a semianalytical static friction model and the atomic molecular dynamics simulation were performed for the mechanism exploration. Friction anisotropy was understood from the differences in contact area, surface stiffness, stiction length, and energy barrier fromthe continuummechanics prospective and fromthat in the stick-slip phenomena at the atomic level.