Elastogranular Buckling of a Slender Ring

Thin flexible-walled structures provide utilitarian geometries in a variety of biological and engineering contexts. Whether describing the origins of certain vascular disorders, the mechanics of thin membranes, or in constructing domed architectures, understanding how these thin objects respond due to external forcing is crucial. Previous work has focused on thin structures deforming within media that, in general, have both compositional and mechanical homogeneity. In comparison, much less is known about the behavior of slender structures embedded in active or driven matter, such as a vibrating granular monolayer. By placing a thin elastic ring within a horizontally driven 2D granular bed, we investigate the phase space of buckling morphologies that arises under gradual compression of this coupled system. Varying the compression rate U, we see a crossover between two distinct regimes, with ring buckling geometries reflecting the degree of granular force homogeneity. These results will bring new insight into how flexible structures deform & pack within complex media, and will be relevant for geometric approaches to cell mechanics, the design of soft robots, the modeling of animal movements, and developing responsive, directable medical devices.