Shearing Rheology and Glassy Behavior in Athermal and Thermalized Models of Granular Materials, Simple Liquids, and Amorphous Solids

颗粒材料、简单液体和非晶固体的非热和热化模型中的剪切流变性和玻璃态行为

• 批准号: 1205800
• 负责人: Stephen Teitel
• 金额: $ 29.67万
• 依托单位: University of Rochester
• 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: 2012-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1205800&HistoricalAwards=false
• 关键词: Shearing; Rheology; Glassy; Behavior; Athermal

TECHNICAL SUMMARYThis award supports theoretical research and education on the nature of equilibrium and driven nonequilibrium critical phenomena in granular materials, glassy forming simple liquids, and related soft matter systems such as foams, emulsions and colloids. Using extensive numerical simulations, the PI will investigate new regions of the jamming phase diagram that characterize a diverse array of physical systems that undergo transitions from flowing liquid-like states to rigid but structurally disordered states. The research will focus on the following activities: (i) The PI will study the rheology of athermal amorphous solids above jamming, characterizing the singular behavior as one approaches the yield stress, and exploring the relation to dynamic heterogeneity. (ii) The PI will investigate the relationship between thermal glassy behavior and the athermal jamming transition. Shear driven steady states at low temperature and low shear strain rate will be used as a new probe to demonstrate whether a true singular thermal glass transition exists. (iii) The PI will explore the effect of different dynamics on the critical behaviors of interest, in particular the difference between mean-field and non-mean-field models of viscous dissipation, and the crossover from inertial to overdamped dynamics. (iv) The PI will study the effect of frictional forces on shear driven athermal jamming. The experimental observation of novel shear jammed states will be explored in simulations. The PI will examine the effect differing models for friction, sliding contacts as opposed to geometric asperities, have on simulation phenomena. These investigations will also address the applicability of concepts and methods from equilibrium statistical mechanics to fundamentally nonequilibrium systems and driven steady states.Undergraduate students will participate in the research, gaining experience, skill, and insight into modern scientific research and methods of numerical simulation. The University of Rochester has several site REU programs that greatly assist in attracting high quality undergraduate students to work on summer research projects. Many of these continue with senior projects or theses during the following year. This project involves international collaboration with Ume¢ªa University in Sweden, as well as other research groups at Duke, Yale, and Rochester. These interactions will provide students with the opportunity to directly confront theory with experiment, to use state of the art high performance computing platforms.NON-TECHNICAL SUMMARYThis award supports theoretical research and education on granular and glassy materials with an emphasis to investigate the nature of the apparent transitions from a flowing liquid-like state to a rigid state with an amorphous structure that occur in granular materials, foams, colloids, emulsions, and liquids cooled to become a glass. The understanding of granular and glassy materials is not only of intrinsic scientific interest, but is important for a wide variety of industrial processes, from the processing of pharmaceuticals, to transportation of seeds and grains, to materials fabrication. This research will contribute to the knowledge base on granular and glassy materials and may lead to advances and improvements in efficiency in many important areas of modern industry and technology. Using extensive numerical simulations, the PI will explore uncharted regions of the jamming phase diagram, a diagram that charts the conditions under which materials undergo transitions from flowing liquid-like states to rigid but structurally disordered states. The jamming transition occurs far from the steady state of equilibrium. While the theory of nonequilibrium statistical mechanics is not well developed, an important research direction is to investigate the extent to which the concepts and methods of equilibrium statistical mechanics can be applied or adapted to the realm of nonequilibrium systems and driven steady states. The PI will contribute to this effort. The PI will explore the relationship between the jamming transition and the transition where a cooling liquid becomes a glass. Because the energy scales in granular systems are usually very high compared to the temperature, temperature does not normally play a role in the jamming transition. The PI will use a novel strategy and innovative techniques to study the nature of the jamming transition at sufficiently high temperatures and compare the signatures of the jamming transition at temperature to the glass transition. Studies of granular systems often neglect friction between particles, but nonetheless are able to observe the jamming transition. The PI plans to study the effect of frictional forces that occur in real granular materials on jamming. The PI will investigate different models through simulation to illuminate experimental observations of novel jammed states that occur under the application of shear strain. Undergraduate students will participate in the research, gaining experience, skill, and insight into modern scientific research and methods of numerical simulation. The University of Rochester has several site REU programs that greatly assist in attracting high quality undergraduate students to work on summer research projects. Many of these continue with senior projects or theses during the following year. This project involves international collaboration with Ume¢ªa University in Sweden, as well as other research groups at Duke, Yale, and Rochester. These interactions will provide students with the opportunity to directly confront theory with experiment, to use state of the art high performance computing platforms.

该奖项支持理论研究和教育的性质平衡和驱动非平衡临界现象的颗粒材料，玻璃形成简单的液体，以及相关的软物质系统，如泡沫，乳液和胶体。利用广泛的数值模拟，PI将研究干扰相图的新区域，这些区域表征了从流动的液体状态到刚性但结构无序状态的各种物理系统。该研究将集中于以下活动：（一）PI将研究非热无定形固体以上堵塞的流变学，表征的奇异行为接近屈服应力，并探讨与动态不均匀性的关系。(ii)PI将研究热玻璃化行为和非热干扰转变之间的关系。在低温和低剪切应变速率下的剪切驱动稳态将作为一个新的探针来证明是否存在真正的奇异热玻璃化转变。(iii)PI将探索不同动力学对感兴趣的关键行为的影响，特别是粘性耗散的平均场和非平均场模型之间的差异，以及从惯性到过阻尼动力学的交叉。(iv)PI将研究摩擦力对剪切驱动的非热堵塞的影响。将在模拟中探索新的剪切堵塞状态的实验观察。PI将检查摩擦、滑动接触与几何粗糙度的不同模型对模拟现象的影响。这些研究还将解决从平衡统计力学的概念和方法的适用性，从根本上非平衡系统和驱动稳态。本科生将参与研究，获得经验，技能和洞察现代科学研究和数值模拟方法。罗切斯特大学有几个网站REU计划，大大有助于吸引高素质的本科生从事暑期研究项目。其中许多人继续在第二年的高级项目或论文。这个项目包括与瑞典的Ume a大学以及杜克大学、耶鲁大学和罗切斯特大学的其他研究小组的国际合作。这些互动将为学生提供直接面对理论与实验的机会，使用最先进的高性能计算平台。非技术总结该奖项支持颗粒和玻璃状材料的理论研究和教育，重点是研究发生在颗粒材料，泡沫，胶体、乳剂和液体冷却后变成玻璃。对颗粒状和玻璃状材料的理解不仅具有内在的科学兴趣，而且对于各种工业过程都很重要，从药物加工到种子和谷物的运输，再到材料制造。这项研究将有助于颗粒和玻璃材料的知识基础，并可能导致现代工业和技术的许多重要领域的效率的进步和提高。利用广泛的数值模拟，PI将探索干扰相图的未知区域，该图描绘了材料从流动的液体状态转变为刚性但结构无序状态的条件。 干扰转变发生在远离平衡的稳定状态。虽然非平衡统计力学理论还不成熟，但一个重要的研究方向是探讨平衡统计力学的概念和方法在多大程度上可以应用或适应于非平衡系统和驱动稳态领域。PI将为此做出贡献。PI将探索堵塞过渡和冷却液变成玻璃的过渡之间的关系。由于颗粒系统中的能量尺度通常比温度高得多，因此温度通常不会在堵塞转变中起作用。PI将使用一种新的策略和创新技术来研究在足够高的温度下干扰转变的性质，并将温度下干扰转变的特征与玻璃化转变进行比较。颗粒系统的研究往往忽略了颗粒之间的摩擦，但仍然能够观察到堵塞过渡。PI计划研究发生在真实的颗粒材料中的摩擦力对堵塞的影响。PI将通过仿真研究不同的模型，以阐明在剪切应变的应用下发生的新堵塞状态的实验观察。 本科生将参与研究，获得经验，技能和洞察现代科学研究和数值模拟方法。罗切斯特大学有几个网站REU计划，大大有助于吸引高素质的本科生从事暑期研究项目。其中许多人继续在第二年的高级项目或论文。这个项目包括与瑞典的Ume a大学以及杜克大学、耶鲁大学和罗切斯特大学的其他研究小组的国际合作。这些互动将为学生提供直接面对理论与实验的机会，使用最先进的高性能计算平台。