Crumple dynamics of localized elastic excitations: interactions, patterns, and mediation of global deformation

We report a variety of elastic localization phenomena in experiments on bent sheets, with aspect ratio ranging from narrow strips to long plates, subject to lateral displacements that induce hysteretic and multi-stable buckling.  Snap-through is mediated by the appearance and propagation of "d-cone"-esque localized regions of high elastic energy; one might be tempted to call these "defects" by analogy with dislocations in crystals, or perhaps "crumplons" ("crumples" and "wrinklons" have been proposed by others).  We document internal and boundary nucleation and escape, pairwise and boundary interactions, something suggestive of curvature screening, and pattern formation both in the form of rapid transient deformation as well as sustained stable organization.  The complex behaviors observed when probing this simple system are representative of those found in plate and shell structures under generic loading.