Static and Dry Friction due to Multiscale Surface Roughness

TL;DR

This paper uses scaling arguments to explain why static and dry friction are nearly always observed in elastic solids due to instabilities at small asperities, providing insight into the rarity of superlubricity.

Contribution

It introduces a theoretical explanation for the ubiquity of static and dry friction based on multiscale surface roughness and elastic instabilities.

Findings

Disordered interfaces exhibit static and dry friction due to asperity instabilities.

Superlubricity is rarely observed because of these inherent instabilities.

Scaling arguments can predict frictional behavior in elastic contacts.

Abstract

It is shown on the basis of scaling arguments that a disordered interface between two elastic solids will quite generally exhibit static and "dry friction" (i.e., kinetic friction which does not vanish as the sliding velocity approaches zero), because of Tomlinson model instabilities that occur for small length scale asperities. This provides a possible explanation for why static and "dry" friction are virtually always observed, and superlubricity almost never occurs.