Folding flakes: the deformation of elastic sheets in a viscous flow

二维材料目前是广泛研究的对象，以利用其独特的机械和电学特性用于技术应用。尽管它们的大部分加工是在液体环境中进行的，例如，在通过离心法选择分散的石墨烯薄片的尺寸或通过喷墨打印沉积它们的过程中，它们与周围流体的相互作用--这可能导致折叠、皱缩甚至断裂，从而不可救药地改变其物理性质--尚未得到表征。事实上，石墨烯薄片的大纵横比意味着，尽管它们具有令人印象深刻的面内硬度，但它们的弯曲刚度非常小，因此很容易被周围流体施加在它们上面的牵引力变形。本项目的目的是表征这些大长宽比材料的流固耦合效应。通过定量实验，我们将研究变形如何影响弹性薄板的沉降--一种与离心过程密切相关的简单流体-结构结构。我们将评估流动引起的变形如何影响这些薄片的沉积速率；我们将探索薄片的纵横比的影响(长和窄的薄片很可能表现得类似于棒状颗粒，其行为要简单得多，并被合理地很好地理解)；并确定在初步实验中观察到的受挫图案如何出现小幅度的初始变形。

Two-dimensional materials are currently the subject of extensive research to harness their unique mechanical andelectrical properties for technological applications. Although much of their processing is performed in a liquid environment, e.g., during the size selection of dispersed graphene flakes by centrifugation or their deposition by ink-jet printing, their interaction with the surrounding fluid - which may result in folding, crumpling or even fracture and thus irremediably alter their physical properties - has not been characterised. Indeed, the large aspect ratio of graphene flakes implies that despite their impressive in-plane stiffness they have a very small bending stiffness and are therefore easily deformed by the traction that the surrounding fluid exerts on them. The aim of this project is to characterise the effect of fluid-structure interaction of these large aspect-ratio materials. Using quantitative experiments, we will study how deformation affects the sedimentation of thin elastic sheets - a simple fluid-structure configuration closely linked to centrifugation processes. We will assess how the flow-induced deformation affects the rate at which such sheets sediment; we will explore the effect of the sheets' aspect ratio (long and narrow sheets are likely to behave similarly to rod-like particles whose behaviour is much simpler and reasonably well understood); and determine how frustrated patterns observed in preliminary experiments emerge small-amplitude initial deformations.