Experiments on Granular Materials and Crumpled Sheets

非技术性这个项目旨在扩展我们对远离平衡的系统的理解。实验集中在两个普遍存在的例子，这样的系统：粒状介质和褶皱的弹性片。颗粒状介质，如沙子或粉末，由大量的单个颗粒组成。同样地，一张起皱的纸（例如纸）是由折痕界定的平面组成的。我们试图了解每个组成颗粒的性质，以及如何确定大量颗粒（颗粒，纸张中的脊）的性质。例如，我们将研究起皱的薄片中的脊网络如何赋予柔软系统刚性。我们将研究大量的沙粒如何在某些条件下聚集成固体，而在其他条件下像液体一样流动。来自马萨诸塞州大学、阿默斯特大学和该地区其他学院的本科生将在新项目的探索工作中发挥关键作用。研究生将接触到各种各样的实验技术。此外，该主题材料在工业上也很重要，将使学生接触到重要的应用问题。技术：该项目涉及两个原型非平衡系统的实验研究-颗粒介质和褶皱弹性片。颗粒介质由通过耗散接触相互作用相互作用的颗粒组成。褶皱板由折痕限定的小平面组成，这两者都是非线性的局部弹性元件。在这两个系统中，组成元素都是宏观的，因此不会受到热波动的影响。该研究旨在确定这种远离平衡系统的相行为，波动，批量响应和结构的一般原则。为此，波动的实验探测，相关的测量线性响应，有序和无序的粒子排列的特点。来自马萨诸塞州大学、阿默斯特大学和该地区其他学院的本科生将在新项目的探索工作中发挥关键作用。研究生将获得接触到许多技术-包括高速视频成像，共焦显微镜，漫射光散射，声学和机械响应技术，以及表面散斑干涉。要研究的材料在工业上也很重要，并将使学生获得重要的应用问题。

Non-technicalThis project seeks to extend our understanding of systems that are far from being in equilibrium. The experiments focus on two ubiquitous examples of such systems: granular media and crumpled elastic sheets. Granular media, such as sand or powders, are made up of a large number of individual grains. Likewise, a crumpled sheet (of paper, for example) is made up of flat facets delimited by creases. We seek to understand the properties of each of the constituent grains and how the properties of a large collection of them (grains, ridges in paper) are determined. For example, we will study how the network of ridges in a crumpled sheet confers rigidity on an otherwise floppy system. We will study how a large collection of sand grains can, under some conditions, pack into a solid form and flow like a liquid under other conditions. Undergraduate students from Univ. of Massachusetts, Amherst and other colleges in the area, will play a crucial role in exploratory work on new projects. Graduate students will gain exposure to a wide variety of experimental techniques. Furthermore, the subject materials are also industrially important and will give the students access to important applied problems.Technical:This project involves experimental studies of two archetypal non-equilibrium systems - granular media and crumpled elastic sheets. Granular media are made up of grains that interact by dissipative contact interactions. A crumpled sheet is made up of facets delimited by creases, both of which are nonlinear, localized elastic elements. In both systems the constituent elements are macroscopic, and therefore are not subject to thermal fluctuations. The research seeks to identify general principles governing phase behavior, fluctuations, bulk response and structure of such far-from-equilibrium systems. To this end, fluctuations are experimentally probed, related to measured linear response, and ordered and disordered arrangements of particles are characterized. Undergraduate students from the Univ. of Massachusetts, Amherst and other colleges in the area will play a crucial role in the exploratory work on new projects. Graduate students will gain exposure to many techniques - including high-speed video imaging, confocal microscopy, diffusive light scattering, acoustic and mechanical response techniques, and surface speckle interferometry. The materials to be studied are also industrially important and will give the students access to important applied problems.