Department of Physics, Clark University, Worcester, Massachusetts 01610, USA.
Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Phys Rev Lett. 2018 Jun 15;120(24):248002. doi: 10.1103/PhysRevLett.120.248002.
It is generally understood that geometric frustration prevents maximal hexagonal packings in uniform filament bundles upon twist. We demonstrate that a hexagonal packed elastic filament bundle can preserve its order over a wide range of twist due to a subtle counteraction of geometric expansion with elastic contraction. Using x-ray scanning and by locating each filament in the bundle, we show the remarkable persistence of order even as the twist is increased well above 360°, by measuring the spatial correlation function across the bundle cross section. We introduce a model which analyzes the combined effects of elasticity including filament stretching and radial and hoop compression necessary to explain this generic preservation of order observed with Hookean filaments.
人们普遍认为，在扭转过程中，几何上的失配会阻止均匀细丝束达到最大的六边形堆积。我们证明，由于几何膨胀与弹性收缩的微妙反作用，一个六边形堆积的弹性细丝束可以在很大的扭转范围内保持其有序性。通过在束截面中定位每个细丝，我们使用 X 射线扫描显示，即使扭转超过 360°，通过测量束截面的空间相关函数，有序性也能显著保持。我们引入了一个模型，该模型分析了包括细丝拉伸和径向及环向压缩在内的弹性的综合效应，这些效应对于解释我们用胡克弹性丝观察到的这种普遍有序性是必需的。
