The Prince’s Dilemma: How Local Heterogeneities Affect the Onset of Frictional Slip

Peas in eider-down beds and asperities at frictional interfaces trouble fairy-tale princesses and nucleate slip events, respectively. We study the onset of such slip events at a two-dimensional frictional interface using soft, transparent elastomer slabs separated by a layer of sand. This system slows rupture propagation to time scales easy to capture experimentally and allows us to directly visualize the full displacement field at the interface. As the top plate is sheared across the interface, stress aggregation forces contact points at the frictional interface to slide and initiates slip events. We systematically introduce localized pockets of stress (peas) to the interface geometry and characterize the effects of these peas on the dynamics of slip nucleation and growth. By tracking the displacement field near the interface, we observe a plethora of these nucleation behaviors, including partial ruptures and local and traveling nucleation.