Crumpling occurs when a thin deformable sheet is crushed under an external load or grows within a confining geometry. Crumpled sheets have large resistance to compression and their elastic energy is focused into a complex network of localized structures1. Different aspects of crumpling have been studied theoretically2,3, experimentally4,5 and numerically6,7. However, very little is known about the dynamic evolution of three-dimensional spatial configurations of crumpling sheets. Herewe present direct measurements of the configurations of a fully elastic sheet evolving during the dynamic process of crumpling under isotropic confinement.We observe the formation of a network of ridges and vertices into which the energy is localized. The network is dynamic. Its evolution involvesmovements of ridges and vertices. Although the characteristics of ridges agree with theoretical predictions, the measured accumulation of elastic energy within the entire sheet is considerably slower than predicted. This could be a result of the observed network rearrangement during crumpling.
Bibliographical noteFunding Information:
We thank G. Cohen for assisting in writing this paper. This work was supported by the United States–Israel Binational Foundation (grant 2004037) and the ERC SoftGrowth project.