Open Conference Systems, StatPhys 27 Main Conference

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Stick-slip dynamics of an intruder in a pack of disks: Effect of the substrate friction and packing fraction.
Ryan Kozlowski, Manuel Carlevaro, Hu Zheng, Lou Kondic, Luis A. Pugnaloni, Karen Daniels, Joshua E. S. Socolar

##manager.scheduler.building##: Edificio Santa Maria
##manager.scheduler.room##: Auditorio San Agustin
Date: 2019-07-08 11:45 AM – 03:30 PM
Last modified: 2019-06-15

Abstract


Stick-slip dynamics is a characteristic feature observed when an elastic component is coupled to a system that exhibits a sharp transition in its force-displacement response. A simple example is the motion of an object, in frictional contact with a base, pulled by a spring (where there is a sharp transition between static and dynamic solid friction forces). Stick-slip behavior is also observed in dense granular materials due to the sharp jamming transition separating elastic deformation from flow. We study the force, velocity and displacement of an intruder disk driven by an elastic pushing arm through a pack of bidisperse disks in an annular cell. Stick-slip is observed due to the interlocking of the grains (stick) and the sudden release of pressure (slip) after a large rearrangement. In one set of experiments, the disks are in frictional contact with the supporting table. In a separate set, the disks float on the surface of a liquid to eliminate the friction with the substrate. For a given packing fraction, stick events occur much less frequently and last shorter in the frictionless case than for the frictional substrate. We identify a peculiar dynamics at low packing fraction where stick-slip gives way to an intermittent flow regime akin to clogging. For both substrates, we study the effect of packing fraction on the distributions of intruder velocity, size of slip events, and waiting times between stick events.