Velocity-driven frictional sliding: Coarsening and steady-state pulse trains

TL;DR

This paper investigates velocity-driven frictional systems with rate-weakening interfaces, revealing the emergence of self-healing slip pulses, coarsening dynamics, and steady-state pulse trains, with detailed theoretical and numerical analysis.

Contribution

It demonstrates the formation of steady propagating pulse trains and coarsening behavior in velocity-driven frictional systems, advancing understanding of slip pulse dynamics.

Findings

Pulse trains are system-length limited and propagate steadily.

Coarsening dynamics lead to a saturated pulse train pattern.

Pulse trains can be accompanied by periodic instabilities at small heights.

Abstract

Frictional sliding is an intrinsically complex phenomenon, emerging from the interplay between driving forces, elasto-frictional instabilities, interfacial nonlinearity and dissipation, material inertia and bulk geometry. We show that homogeneous rate-and-state dependent frictional systems, driven at a prescribed boundary velocity -- as opposed to a prescribed stress -- in a range where the frictional interface is rate-weakening, generically host self-healing slip pulses, a sliding mode not yet fully understood. Such velocity-driven frictional systems are then shown to exhibit coarsening dynamics saturated at the system length in the sliding direction, independently of the system's height, leading to steadily propagating pulse trains. The latter may be viewed as a propagating phase-separated state, where slip and stick characterize the two phases. While pulse trains' periodicity is coarsening-limited by the system's length, the single pulse width, characteristic slip velocity and propagation speed exhibit rich properties, which are comprehensively understood using theory and extensive numerics. Finally, we show that for sufficiently small system heights, pulse trains are accompanied by periodic elasto-frictional instabilities.