Probing locally the onset of slippage at a model multi-contact interface

Abstract

We report on the multi-contact frictional dynamics of model elastomer surfaces rubbed against bare glass slides. The surfaces consist of layers patterned with thousands spherical caps (radius of curvature 100 $\mu$m) distributed both spatially and in height, regularly or randomly. Use of spherical asperities yields circular micro-contacts whose radius is a direct measure of the contact pressure distribution. In addition, optical tracking of individual contacts provides the in-plane deformations of the tangentially loaded interface, yielding the shear force distribution. We then investigate the stick-slip frictional dynamics of a regular hexagonal array. For all stick phases including the initial one, slip precursors are evidenced. They are found to propagate quasi-statically, normally to the iso- pressure contours. A simple quasi-static model relying on the existence of interfacial stress gradients is derived and predicts qualitatively the position of slip precursors.

5 pages, 5 figures

References in corpus (3)

• The dependence of the dry friction threshold on rupture dynamics
• Instabilities at Frictional Interfaces: Creep Patches, Nucleation and Rupture Fronts
• Role of friction-induced torque in stick-slip motion

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