Nat Mater. 2010 Dec;9(12):993-7. doi: 10.1038/nmat2893. Epub 2010 Nov 14.
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 structures. Different aspects of crumpling have been studied theoretically, experimentally and numerically. However, very little is known about the dynamic evolution of three-dimensional spatial configurations of crumpling sheets. Here we 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 involves movements 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.
当薄的可变形片材在外部负载下被压碎或在约束几何形状内生长时，就会发生起皱。起皱的薄片具有很大的抗压能力，其弹性能集中在复杂的局部结构网络中。起皱的不同方面已经在理论、实验和数值上进行了研究。然而，对于起皱薄片的三维空间构型的动态演化，人们知之甚少。在这里，我们展示了在各向同性约束下起皱的动态过程中，完全弹性片的构型的直接测量结果。我们观察到一个由脊和顶点组成的网络的形成，能量被局部化在其中。该网络是动态的，其演化涉及脊和顶点的运动。尽管脊的特征与理论预测相符，但整个片材内弹性能量的测量积累速度明显慢于预测。这可能是由于在起皱过程中观察到的网络重排所致。
