Title: Elastogranular Mechanics

Author (Poster): David Schunter, Boston University

Abstract:

A deforming elastic structure embedded in a discrete granular array arises in the locomotion of certain burrowing animals, the drilling of deep hydrocarbon wells, and in the removal of sediment from the interior walls of piped networks. Within these diverse elastogranular systems, a geometric hierarchy emerges between a dissipative granular medium and a compliant slender structure. By increasing granular density or shrinking the area of confinement, initially disordered states of 2D granular media will jam, the underlying lattice structure becoming progressively more crystalline. We find that an intruding elastica can produce the same response, observing a characteristic arc-length of injection necessary for jamming to occur and a characteristic half-wavelength of deformation that defines the length of the region into which the elastica will localize. In post-jamming configurations, we offer insight into stress relaxation in granular systems, looking at the vertical dislocation of grains in critically jammed 2D arrays. These elastogranular systems provide simple mechanical models of physical behavior abundant in both nature and industry.