The Fundamental Physics of the Onset of Frictional Motion: How does friction start?

by Jay Fineberg

Hebrew University

at Physics Colloquium

Tue, 22 Apr 2025, 12:00
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015

Abstract

Recent experiments have demonstrated that rapid rupture fronts, akin to earthquakes, are responsible for the transition to frictional motion. These dynamic rupture fronts ("laboratory earthquakes") have a singular form whose dynamics are well-described by the theory that describes the physics of how things break – or fracture mechanics. Ruptures, however, need to be created within initially rough frictional interfaces, before they are able to propagate. This is the reason that "static friction coefficients" are not well-defined; frictional ruptures can nucleate for a wide range of applied forces. A critical open question is, he therefore, how the nucleation of rupture fronts actually takes place. We experimentally demonstrate that rupture front nucleation is prefaced by slow nucleation fronts. These nucleation fronts, which are self-similar, are not described by our current understanding of fracture mechanics. The nucleation fronts emerge from initially rough frictional interfaces at well-defined stress thresholds, evolve at characteristic velocity and time scales governed by stress levels, and propagate within a frictional interface to form the initial rupture from which fracture mechanics take over. These results are of fundamental importance to questions ranging from earthquake nucleation and prediction to processes governing material failure.

Created on 14-02-2025 by Kats, Yevgeny (katsye)
Updaded on 10-04-2025 by Kats, Yevgeny (katsye)