Collective behavior of viscoelastic asperities as a model for static and kinetic friction

TL;DR

This paper introduces a statistical model of viscoelastic asperities to explain static and kinetic friction, revealing how collective microscale behavior leads to macroscopic friction phenomena.

Contribution

It presents a novel collective model linking microscale viscoelastic contact behavior to macroscopic friction, offering new insights and interpretations of the state variable.

Findings

Collective response causes macroscopic friction features.

Model parameters relate to material and surface properties.

Comparison with rate and state models offers new interpretation.

Abstract

We propose a statistical model for static and sliding friction between rough surfaces. Approximating the contact between rough surfaces by the contact of an ensemble of one-dimensional viscoelastic elements with a rough rigid surface, we study the collective behavior of the elements. We find that collective response of the contacts can lead to macroscopic behavior very different from the microscopic behavior. Specifically, various observed features of friction emerge as collective phenomena, without postulating them directly at the microscale. We discuss how parameters in our model can be related to material and surface properties of the contacting surfaces. We compare our results to commonly used rate and state phenomenological models, and propose a new interpretation of the state variable.