How collective asperity detachments nucleate slip at frictional interfaces

• Published in: Proceedings of the National Academy of Sciences - PNAS 2019-11, Vol.116 (48), p.23977-23983
• Main Authors: de Geus, Tom W. J., Popović, Marko, Rosso, Alberto, Wyart, Matthieu
• Format: Article
• Language: English
• Subjects: Amorphous materials; Asperity; Avalanches; Decay rate; Friction; Interfaces; Landslides; Nucleation; Physical Sciences; Physics; PNAS Plus; Size effects; Slip
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1906551116

Sliding at a quasi-statically loaded frictional interface can occur via macroscopic slip events, which nucleate locally before propagating as rupture fronts very similar to fracture. We introduce a microscopic model of a frictional interface that includes asperity-level disorder, elastic interaction between local slip events, and inertia. For a perfectly flat and homogeneously loaded interface, we find that slip is nucleated by avalanches of asperity detachments of extension larger than a critical radius Ac governed by a Griffith criterion. We find that after slip, the density of asperities at a local distance to yielding x σ presents a pseudogap P(x σ)∼(x σ)θ, where θ is a nonuniversal exponent that depends on the statistics of the disorder. This result makes a link between friction and the plasticity of amorphous materials where a pseudogap is also present. For friction, we find that a consequence is that stick–slip is an extremely slowly decaying finite-size effect, while the slip nucleation radius Ac diverges as a θ-dependent power law of the system size. We discuss how these predictions can be tested experimentally.