The Wrinkle-to-Crumple Transition in Thin Elastic Solids
The last decade has seen a renaissance in the buckling of thin elastic solids, in part because of its impact on the mechanics of synthetic skins, biological tissues, textiles, and 2D materials like graphene. Significant effort has been devoted to understanding and exploiting buckled morphologies that decorate otherwise planar surfaces. Yet, we show that one of the most-studied morphologies—sinusoidal wrinkling—does not persist in a variety of curved geometries. Instead, smooth wrinkles generically give way to sharp “crumples”. We characterize this transition in a suite of experiments across geometries and scales, using ultrathin polymer films on liquid droplets and macroscopic membranes that we inflate with gas. These setups reveal robust morphological features of the crumpled phase, and they allow us to disentangle the effects of curvature and compression. Our work highlights the need for a theoretical understanding of this ubiquitous elastic building block, and we lay out concrete directions for such studies.