The slippery slope of frictional layered structures

Two sliding frictional surfaces can display a strong intermittent response known as stick-slip, characterized by a succession of loading phases, interrupted by sudden macroscopic slip events. The static friction coefficient describes the onset of these events; however, it is now known not to be a well-defined material constant [1]. A stochastic nature of this friction coefficient has recently been suggested, with macroscopic slips triggered by microscopic avalanches. Such small-scale events act as scars where inertia leads to local weakening; when a critical size is reached, a slip-event propagates along the interface [2]. We use experiments and simulations to investigate the role of inertial interactions through bulk elasticity of a frictional layered system. Specifically, we investigate a system of stacked plates with frictional interfaces forced to slide simultaneously. We observe that the statistical properties of the stick-slip events in the multilayered set-up deviate from that of a single layer, suggesting a nontrivial coupling across the stack. This work may bring a better understanding of the seismic behavior of layered geological formations.

[1] Ben-David, O., & Fineberg, J. (2011). PRL, 106(25), 254301.
[2] de Geus, T. W. J, et al. (2019). PNAS, 116(48), 23977-23983.