Correlation between slip precursors and topological length scales at the onset of frictional sliding

TL;DR

This study explores how the interaction between slip precursors and surface geometric length scales influences the onset of frictional sliding, using numerical simulations to reveal how surface structures affect slip behavior and transition to sliding.

Contribution

It introduces a numerical analysis of the interplay between slip precursors and geometric length scales, extending understanding of frictional sliding with structured surfaces.

Findings

Different surface structures trigger specific detachment sequences.

Hierarchical and anisotropic features lead to smooth transition to sliding.

Surface patterning influences slip precursor localization and occurrence.

Abstract

Understanding the interplay between concurrent length scales is a fundamental issue in many problems involving friction between sliding interfaces, from tribology to the study of earthquakes and seismic faults. On the one hand, a macroscopic sliding event is preceded by slip precursors with a characteristic propagation length scale. On the other hand, the emergent frictional properties can be modified by surface patterning depending on their geometric length scale. This suggests that macroscopic sliding of structured surfaces is governed by the interplay between the length scale of the slip precursors and those characterizing the geometric features. In this paper, we investigate these aspects by means of numerical simulations using a two-dimensional spring-block model. We discuss the influence of the geometric features on the occurrence and localization of slip precursors, extending the study to interfaces characterized by two geometric length scales. We find that different types of detachment sequences are triggered by specific surface structures, depending on their scales and relation to sliding direction, leading to a macroscopically smooth transition to sliding in the case of hierarchical and/or anisotropic features. These concepts could be exploited in devices switching from static to dynamic sliding, and can contribute to an improvement in the understanding and interpretation of seismic data