Armouring of a Frictional Interface by Mechanical Noise

Area of Science:

• Physics
• Materials Science
• Geophysics

Background:

• Dry frictional interfaces under shear commonly exhibit stick-slip behavior.
• The amplitude of stick-slip cycles is influenced by rupture nucleation probability and microscopic event triggering rates.
• The distribution of 'soft spots' (P(x)) dictates the rate of microscopic event triggering.

Purpose of the Study:

• To explain the dependence of the exponent (α) on disorder statistics in frictional interface models.
• To elucidate the role of inertia in the 'armouring' mechanism of frictional interfaces.
• To develop a simplified model that captures the essential physics of disorder-driven exponent variation.

Main Methods:

• Development of minimal models of frictional interfaces incorporating disorder, inertia, and long-range elasticity.
• Analysis of the 'armouring' mechanism and its effect on the soft spot distribution P(x).
• Introduction and analysis of a single-particle toy model with inertia and disorder.

Main Results:

• Discovery of an 'armouring' mechanism that stabilizes frictional interfaces after large slip events.
• Identification of a non-trivial exponent (α) in the soft spot distribution P(x) that depends on inertia.
• Demonstration that a single-particle model with inertia and disorder analytically reproduces the non-trivial exponent (α) and its relation to disorder statistics.

Conclusions:

• Inertia plays a crucial role in the 'armouring' mechanism and the resulting stabilization of frictional interfaces.
• The observed dependence of the exponent (α) on disorder statistics can be explained by including inertia in simplified models.
• A single-particle model effectively captures the complex behavior of disordered frictional systems, providing analytical insights into the exponent's origin.