Micro-slip field at a rough contact driven towards macroscopic sliding

Julien Scheibert (1) , Georges Debregeas (1) , Alexis Prevost (1)

1 LPS - Laboratoire de Physique Statistique de l'ENS

The incipient sliding of a multicontact interface between a smooth glass sphere and a rough elastomer block is studied using an image correlation velocimetry technique. The displacement field of the elastomer's surface is measured both inside and outside the apparent contact region with a submicrometer displacement resolution. For a given shear load, a coexistence between an inner stick region surrounded by an outer slip annulus is observed. The stick region extension decreases with increasing load and eventually vanishes at the sliding threshold. These measurements allow for the first quantitative test of Cattaneo and Mindlin (CM) classical model of the incipient sliding of a smooth interface. Small deviations are observed and interpreted as a result of the finite compliance of the rough interface, a behavior which contrasts with Amontons' law of friction assumed to be valid locally in CM's model. We illustrate how these measurements actually provide a method for probing the rheology of the rough interface, which we find to be of the elasto-plastic type.

Keywords: Contact mechanics; friction law; incipient sliding; micro-slip; image correlation velocimetry technique; multicontact; interfacial rheology

Domains: Soft Condensed Matter [cond-mat.soft]

Julien Scheibert, Georges Debregeas, Alexis Prevost. Micro-slip field at a rough contact driven towards macroscopic sliding. 2008. ⟨hal-00322643v1⟩