Hohlfeld Evan, Davidovitch Benny
Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Jan;91(1):012407. doi: 10.1103/PhysRevE.91.012407. Epub 2015 Jan 20.
The adhesion of a stiff film onto a curved substrate often generates elastic stresses in the film that eventually give rise to its delamination. Here we predict that delamination of very thin films can be dramatically suppressed through tiny, smooth deformations of the substrate, dubbed here "wrinklogami," that barely affect the macro-scale topography. This "prolamination" effect reflects a surprising capability of smooth wrinkles to suppress compression in elastic films even when spherical or other doubly curved topography is imposed, in a similar fashion to origami folds that enable construction of curved structures from an unstretchable paper. We show that the emergence of a wrinklogami pattern signals a nontrivial isometry of the sheet to its planar, undeformed state, in the doubly asymptotic limit of small thickness and weak tensile load exerted by the adhesive substrate. We explain how such an "asymptotic isometry" concept broadens the standard usage of isometries for describing the response of elastic sheets to geometric constraints and mechanical loads.
刚性薄膜附着在弯曲基底上时,薄膜中常常会产生弹性应力,最终导致薄膜分层。在此,我们预测,通过基底的微小、平滑变形(在此称为“皱纹折纸”),几乎不会影响宏观尺度的形貌,却能显著抑制极薄薄膜的分层。这种“预分层”效应反映出一种惊人的能力:即使施加球形或其他双曲面形貌,平滑皱纹也能抑制弹性薄膜中的压缩,这类似于折纸褶皱能够用不可拉伸的纸张构建弯曲结构。我们表明,在由粘性基底施加的小厚度和弱拉伸载荷的双渐近极限下,皱纹折纸图案的出现标志着薄膜与其平面未变形状态之间存在非平凡等距性。我们解释了这种“渐近等距性”概念如何拓宽了等距性在描述弹性薄板对几何约束和机械载荷响应方面的标准用法。