UNS: Imaging inhomogeneous stress networks in colloidal glasses and gels to determine their role in the bulk response of disordered suspensions

UNS：对胶体玻璃和凝胶中的不均匀应力网络进行成像，以确定它们在无序悬浮液的整体响应中的作用

基本信息

批准号：
1509308
负责人：
Itai Cohen
金额：
$ 35.18万
依托单位：
Cornell University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2015
资助国家：
美国
起止时间：
2015-07-01 至 2019-12-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1509308&HistoricalAwards=false
关键词：
UNS Imaging inhomogeneous stress networks

项目摘要

CBET - 1509308 Cohen, Itai Through various processes a piece of glass can be designed to safely shatter, be bullet proof, or flexible and tough. The glass properties can be changed by manipulating the microscopic forces between the molecules that make up the glass. Learning how to better control the distribution of these microscopic forces and how they evolve under various loading conditions is an important technological challenge. This projects aims to visualize and determine the forces and construct models for the glass. The understanding gained through these studies will have very broad impact with the potential to change industrial manufacturing practices. Both graduate and undergraduate students will be involved in the research and outreach and conference programs will benefit student and postdoctoral researchers and industries in the up-state New York area.The deformation of disordered dense colloidal suspensions is governed by the nonlinear behavior of inhomogeneous stress networks that develop within the material in response to applied stresses. Determining how evolution of these local stress networks governs bulk rheological behaviors remains an outstanding scientific challenge. A key hurdle for developing this understanding is the lack of methods for experimentally measuring the local stresses within suspensions. In this project, a novel method - Stress Assessment from Local Structural Anisotropy (SALSA)- will enable groundbreaking capabilities for determining stresses associated with sample volumes that extend down to the single particle scale. In combination with a newly developed confocal rheometer device, pioneering experiments including, indentation, compression, shear, and biaxial shear are being conducted to quantifying how inhomogeneous stress networks collude to govern the bulk mechanical behavior of dense disordered colloidal suspensions. The application of SALSA is also being extended to more complicated interparticle potentials arising from depletion interactions. This extended capability is being used to study how crack propagation is altered as the gel that it is traveling through approaches a percolation threshold. In addition to being excellent model systems, colloids are an important technology in and of themselves. In particular, controlling the jamming of colloidal suspensions is important for processing products ranging from toothpastes to paints. As such, the findings made through this project will have very broad impact with the potential to change practices in both the scientific and industrial communities.

CBET -1509308 Cohen，ITAI通过各种过程，可以设计一块玻璃，以安全地粉碎，防弹或灵活而坚韧。可以通过操纵构成玻璃的分子之间的微观力来改变玻璃特性。学习如何更好地控制这些微观力量的分布以及它们在各种负载条件下如何发展是一个重要的技术挑战。该项目旨在可视化和确定玻璃的力和构造模型。通过这些研究获得的理解将产生非常广泛的影响，并有可能改变工业制造实践。研究生和本科生都将参与研究，外展和会议计划，将使纽约州纽约地区的学生和博士后研究人员和行业受益。无均衡压力网络的非线性行为构成了混乱的密集胶体悬架的变形。响应于应用应力而在材料中发展。确定这些局部压力网络的演变如何控制批量流变学行为仍然是一个杰出的科学挑战。建立这种理解的关键障碍是缺乏实验测量悬浮液中局部应力的方法。在这个项目中，一种新的方法 - 局部结构各向异性（SALSA）的应力评估 - 将使突破性能力确定与延伸至单个粒子尺度的样品体积相关的应力。结合新开发的共聚焦流变仪装置，正在进行开创性的实验，包括凹痕，压缩，剪切和双轴剪切，以量化如何核对不均匀的应力网络，以控制密集无序无序的胶体悬浮液的块状机械行为。莎莎的应用也扩展到耗尽相互作用引起的更复杂的颗粒域电位。这种扩展的能力被用来研究裂纹传播是如何改变的，因为它正在通过渗透阈值传播的凝胶。除了成为出色的模型系统外，胶体本身就是一项重要的技术。特别是，控制胶体悬浮液的干扰对于处理从牙膏到油漆的产品很重要。因此，通过该项目提出的发现将对科学和工业社区的改变实践产生非常广泛的影响。