Physicists Discover Mechanisms of Wrinkle and Crumple Formation
Smooth wrinkles and sharply crumpled regions are familiar motifs in biological and synthetic sheets, such as plant leaves and crushed foils, say physicists Benny Davidovitch, Narayanan Menon and colleagues at the University of Massachusetts Amherst, but how a featureless sheet develops a complex shape has long remained elusive. Now, in a cover story of the journal, Proceedings of the National Academy of Sciences, the physicists report that they have identified a fundamental mechanism by which such complex patterns emerge spontaneously.
Davidovitch says they were inspired and moved toward a solution by thinking about how a familiar birthday balloon, made of two circular mylar foils, wrinkles and crumples (two separate processes). The two foils start flat, but when glued together around their edges and injected with helium gas to create higher-than-atmospheric pressure inside, they spontaneously changes shape to accommodate the gas