Transition from static to kinetic friction: Insights from a 2D model

TL;DR

This paper presents a 2D spring-block model that explains the transition from static to kinetic friction, reproducing experimental results and predicting precursor length evolution based on applied loads and friction coefficients.

Contribution

The study introduces a minimalistic 2D model that captures micro-slip precursors and relates microscopic and macroscopic friction coefficients, aligning with experimental observations.

Findings

Reproduces experimental precursory micro-slip fronts

Predicts precursor length evolution with applied loads

Shows crack speed depends on stresses and friction coefficients

Abstract

We describe a 2D spring-block model for the transition from static to kinetic friction at an elastic slider/rigid substrate interface obeying a minimalistic friction law (Amontons-Coulomb). By using realistic boundary conditions, a number of previously unexplained experimental results on precursory micro-slip fronts are successfully reproduced. From the analysis of the interfacial stresses, we derive a prediction for the evolution of the precursor length as a function of the applied loads, as well as an approximate relationship between microscopic and macroscopic friction coefficients. We show that the stress build-up due to both elastic loading and micro-slip-related relaxations depend only weakly on the underlying shear crack propagation dynamics. Conversely, crack speed depends strongly on both the instantaneous stresses and the friction coefficients, through a non-trivial scaling parameter.