Connecting Glassy Dynamics to Micro-Scale Elasticity

将玻璃动力学与微尺度弹性联系起来

• 批准号: 1236378
• 负责人: David Pine
• 金额: $ 33万
• 依托单位: New York University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-15 至 2016-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1236378&HistoricalAwards=false
• 关键词: Connecting; Glassy; Dynamics; Micro; Scale

1236378PI: WyartParticulate materials, such as suspensions or granular matter, are the most commonly used materials in industry after water. However, explaining their rheological properties remains a challenge. These systems are complicated by the presence of disorder as well as by structural and dynamical heterogeneities, often on multiple length scales. At high densities, such a granular fluid undergoes a jamming or glass transition where the dynamics stop. In recent years there has been a considerable effort to characterize this transition, and it has been realized that dynamical heterogeneities play a key role. However, there is no consensus concerning what causes such heterogeneities. This project will develop a novel method to measure the micro-scale elasticity of amorphous materials. This approach will be used both experimentally and numerically to characterize the disorder and heterogeneities of amorphous solids, and to investigate the jamming transition by which they are formed. The method consists of introducing probe particles of controlled shapes and sizes. Thermal noise causes the probe particles to rotate on a time scale governed by the elasticity of their local environment, and by their shape and size. Measuring the rotational dynamics of the probe by means of confocal microscopy, light scattering, or numerically in simulations will give access to local elastic properties. The range of time scales and length scales can be tuned by controlling the shape and size of the probes. This method will be employed in colloidal suspensions, both experimentally and numerically, to measure the evolution of elasticity and its spatial heterogeneities as the concentration of colloids is increased, and to test fundamental theories of the glass transition.This project will create an experimental method to probe the microscopic properties of disordered granular materials, the most commonly used materials in industry after water. This method will address questions of fundamental and practical importance in the fields of particle flow, biophysics, soil mechanics, and material science. Insights gained from this study will help improve the design of glassy materials and advance our understanding of clogging or jamming, which are of important for multi-phase flows relevant to the oil industry and potentially for the lethal vaso-occlusive eventt?clogging?occurring in sickle cell disease. In addition to these applications, the subject matter of this project lends itself to educational and community outreach activities.

1236378PI：Wya颗粒材料，如悬浮液或颗粒物，是仅次于水的工业中最常用的材料。然而，解释它们的流变性仍然是一个挑战。这些系统由于无序的存在以及结构和动力学的异质性而变得复杂，通常是在多个长度尺度上。在高密度下，这样的颗粒流体会经历堵塞或玻璃化转变，在那里动力学停止。近年来，人们花了相当大的努力来描述这种转变，人们已经意识到动力非均质性起着关键作用。然而，对于是什么导致了这种异质性，还没有达成共识。该项目将开发一种新的方法来测量非晶态材料的微尺度弹性。这种方法将用实验和数值方法来表征无定形固体的无序性和非均质性，并研究形成它们的阻塞转变。该方法包括引入形状和大小可控的探针颗粒。热噪声导致探测器粒子在由其局部环境的弹性以及它们的形状和大小控制的时间尺度上旋转。通过共焦显微镜、光散射或数值模拟来测量探头的旋转动力学，可以获得局部弹性特性。时间尺度和长度尺度的范围可以通过控制探头的形状和大小来调节。这一方法将用于胶体悬浮液的实验和数值计算，以测量随着胶体浓度的增加弹性的演化及其空间非均质性，并测试玻璃化转变的基本理论。本项目将创建一种实验方法来探索无序颗粒材料的微观性质，无序颗粒材料是继水之后工业中最常用的材料。这种方法将解决颗粒流、生物物理学、土力学和材料科学领域中的基本和实际重要问题。从这项研究中获得的见解将有助于改进玻璃材料的设计，并增进我们对堵塞或堵塞的理解，这对与石油工业相关的多相流以及可能发生在镰状细胞疾病中的致命血管堵塞事件具有重要意义。除了这些应用外，该项目的主题还适用于教育和社区外联活动。