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Deformation and flow of highly polydisperse amorphous solids

高度多分散非晶固体的变形和流动

基本信息

批准号：
1804186
负责人：
Eric Weeks
金额：
$ 30.64万
依托单位：
Emory University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-07-15 至 2022-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1804186&HistoricalAwards=false
关键词：
Deformation flow highly polydisperse amorphous

项目摘要

This is an experimental study of how disordered materials flow. The flow of materials like mud, cement, foam, and dirt in landslides is quite different from the flow of liquids. These materials have been studied before but their complexity makes it difficult to determine general principles about how these interesting substances flow. Some past studies used simple systems to try to mimic these complicated materials: a standard simple system is a liquid full of round particles with a specific size. It is clear that these simple systems fail to reproduce many of the interesting flow behaviors of the real materials. This work studies the flow of materials with intermediate complexity: liquids with particles with a wide variety of sizes in the same sample. Optical microscopy is used to examine the motion of the particles and see how they rearrange, for example, how small particles are forced to move around large particles. These observations will be used to develop basic ideas about the flow of other disordered materials, which will lead to better understanding of how to move, mix, and process complex materials of industrial relevance. Undergraduate and graduate students will be engaged in conducting the research. Additionally, the researchers regularly host field trips of visiting students (first grade through high school) to teach them about soft squishy materials and how scientists study these materials.The objective of this project is to understand how amorphous solids flow, in particular to connect particle-scale rearrangements to macroscopic flow profiles and rheological behavior. The samples are highly polydisperse emulsions, where the largest droplets are ten times the radius of the smallest droplets (or more). Flowing and sheared samples are studied with video and confocal microscopy. This enables the motion of individual droplets to be measured. When a large strain is applied, droplets rearrange irreversibly. These rearrangements can be quantified in terms of topological changes, magnitudes of displacements, and how non-affine the flow is locally. The project connects these details of droplet rearrangements to the size of individual droplets. More broadly, these details likely depend on the overall droplet size distribution. Additionally, the microscopic details must connect with macroscopic rheological properties. Complementary experiments can be done with solid particles, and simulations provide a third route to explore these questions. The overall motivation is to bridge the gap between prior model systems that studied mixtures of particles of fairly similar sizes, and complex real-world materials such as mud and cement. This will lead to new microscopic understanding of the shear of amorphous materials with large size polydispersity. At least one undergraduate and one graduate student will be involved with the research. The research team will also host field trips each year to demonstrate to visiting students that cutting edge science can be done with simple materials which they can literally get their hands on.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这是一个关于无序物质如何流动的实验研究。在山体滑坡中，泥浆、水泥、泡沫和泥土等物质的流动与液体的流动大不相同。这些物质以前曾被研究过，但它们的复杂性使得很难确定这些有趣物质流动的一般原理。过去的一些研究使用简单的系统来试图模拟这些复杂的材料：一个标准的简单系统是一个充满特定大小的圆形颗粒的液体。很明显，这些简单的系统不能再现真实材料的许多有趣的流动行为。这项工作研究了具有中等复杂性的材料流动：在同一样品中具有各种尺寸的颗粒的液体。光学显微镜被用来检查粒子的运动，看看它们是如何重新排列的，例如，小粒子是如何被迫在大粒子周围移动的。这些观察结果将用于发展关于其他无序材料流动的基本思想，这将有助于更好地理解如何移动、混合和处理与工业相关的复杂材料。本科生和研究生将参与研究。此外，研究人员还定期组织访问学生（从一年级到高中）进行实地考察，教他们关于软黏糊糊的材料以及科学家如何研究这些材料。该项目的目的是了解无定形固体是如何流动的，特别是将颗粒尺度的重排与宏观流动曲线和流变行为联系起来。样品是高度多分散的乳液，其中最大的液滴是最小液滴半径的十倍（或更多）。用视频和共聚焦显微镜研究了流动和剪切样品。这样就可以测量单个液滴的运动。当施加较大的应变时，液滴会不可逆地重新排列。这些重排可以根据拓扑变化、位移大小以及流动在局部的非仿射程度来量化。该项目将液滴重新排列的这些细节与单个液滴的大小联系起来。更广泛地说，这些细节可能取决于液滴的总体尺寸分布。此外，微观细节必须与宏观流变特性相联系。补充实验可以用固体颗粒进行，模拟为探索这些问题提供了第三条途径。总的动机是为了弥合先前模型系统之间的差距，这些模型系统研究的是相当相似大小的颗粒混合物，以及复杂的现实世界材料，如泥浆和水泥。这将对具有大尺寸多分散性的非晶态材料的剪切产生新的微观认识。至少有一名本科生和一名研究生将参与这项研究。研究小组每年还将组织实地考察，向来访的学生展示，他们可以用简单的材料来完成尖端科学，而且他们真的可以得到这些材料。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Rearrangement of two dimensional aggregates of droplets under compression: Signatures of the energy landscape from crystal to glass

压缩下二维液滴聚集体的重新排列：从晶体到玻璃的能量景观特征

DOI：
10.1103/physrevresearch.2.023070
发表时间：
2020
期刊：
Physical Review Research
影响因子：
4.2
作者：
Ono-dit-Biot, Jean-Christophe;Soulard, Pierre;Barkley, Solomon;Weeks, Eric R.;Salez, Thomas;Raphaël, Elie;Dalnoki-Veress, Kari
通讯作者：
Dalnoki-Veress, Kari

Isomorph invariance of dynamics of sheared glassy systems

剪切玻璃体系动力学的同构不变性