Controlling Microscopic Friction through Mechanical Oscillations

TL;DR

This paper investigates how mechanical oscillations applied to a substrate can control and reduce microscopic friction, with different mechanisms identified for stick-slip and sliding regimes, enabling friction tuning at the nanoscale.

Contribution

It reveals distinct mechanisms for friction reduction via oscillations in different motion regimes and demonstrates the possibility of sustained motion solely through oscillations.

Findings

Friction can be tuned and reduced by adjusting oscillation frequency and amplitude.

In stick-slip, friction reduction is due to enhanced surface diffusion.

In sliding, parametric resonances occur from interplay of washboard and oscillation frequencies.

Abstract

We study in detail the recent suggestions by Tshiprut et al. [Phys. Rev. Lett. 95, 016101 (2005)] to tune tribological properties at the nanoscale by subjecting a substrate to periodic mechanical oscillations. We show that both in stick-slip and sliding regimes of motion friction can be tuned and reduced by controlling the frequency and amplitude of the imposed substrate lateral excitations. We demonstrate that the mechanisms of oscillation-induced reduction of friction are different for stick-slip and sliding dynamics. In the first regime the effect results from a giant enhancement of surface diffusion, while in the second regime it is due to the interplay between washboard and oscillation frequencies that leads to the occurrence of parametric resonances. Moreover we show that for particular set of parameters it is possible to sustain the motion with the only oscillations.