Plasticity and Avalanches: Connections Between Systems Ranging from Metals to Granular Materials

塑性和雪崩：从金属到颗粒材料的系统之间的连接

• 批准号: 1005209
• 负责人: Karin Dahmen
• 金额: $ 29万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2015-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1005209&HistoricalAwards=false
• 关键词: Plasticity; Avalanches; Connections; Between; Systems

TECHNICAL SUMMARYThis award supports theoretical research and education to combine concepts from statistical physics, materials science, solid mechanics, engineering, granular mechanics, and metallurgy to advance and unify understanding of the response of materials to external stresses. Recent experiments on the shear response of small metal or ice crystals reveal that the deformation is not smooth, but rather jerky, through a sequence of dislocation-slip events that span a broad range of sizes. Similarly, densely packed granular materials respond to shear with a sequence of slip avalanches. In both cases, the distribution of slip event sizes is described by a power law over several decades. The associated power law exponents are the same for a large class of different materials; they are "universal". Simulations of these systems are useful, but connections between different systems can often more easily be recognized using analytic approaches. Building on recent analyses, the size of the class of systems having avalanches and showing the same behavior on long length scales, can be assessed. In this project, the PI will analytically compute predictions for the dependence of the slip-avalanche statistics on a series of important experimental tuning parameters, such as strain rate, stress rate, disorder, and temperature. The approach will also be used to investigate the connection between driven dynamics at low temperature and relaxation dynamics at higher temperature in the absence of driving. A main goal is to expand and test recent analytical approaches in order to unify the understanding of non-equilibrium phenomena that were previously thought to be unrelated. The methods include techniques from the theory of phase transitions, the renormalization group, disordered-systems theory, Monte Carlo simulations and molecular dynamics simulations. Predictions from these studies are compared with experiments on plastic deformation, granular materials, magnets, and results from large-scale simulations. The highly interdisciplinary nature of this research promotes an ideal learning environment for the diverse group of graduate and undergraduate students working on this project. Collaborations with a network of national and international theorists, experimentalists, materials scientists, engineers, and seismologists will be fostered. Simulation codes will be shared with the research community. Potential applications of this work include: materials-failure prediction and control on a broad range of scales, from nanodevices to bulk materials, nondestructive materials testing, improved understanding of the often undesirable Portevin-Le Chatelier effect in metallurgy, increased materials stability during processing, improved understanding of jamming and avalanches of granular materials such as powders and grains in silos, and long-term security of magnetic information storage.NONTECHNICAL SUMMARYThis award supports theoretical research and education to combine concepts from statistical physics, materials science, solid mechanics, engineering, granular mechanics, and metallurgy to advance and unify understanding of how materials respond to external stresses. Many systems crackle when they are pushed slowly: Wood can crackle when it is slowly bent. Similarly, small metal or ice crystals deform in a rather jerky way, through a sequence of local slip events that span a broad range of size. In these slip events, weak spots fail in response to the slowly increasing applied shear stress. On a much larger scale roughly the same phenomenon gives rise to earthquakes, when the slow tectonic motion triggers slips of weak spots in the earth's crust. Many other systems exhibit similar failure avalanches, ranging from granular materials to magnets. This project develops a quantitative understanding of the similarities of the avalanche statistics of these systems, many of which were previously studied separately. The goal is to predict to what extent the results and understanding can be transferred from one system to another. Recently, powerful mathematical tools have been developed to answer these questions. These methods will be coupled with computational simulations and comparisons with experiments on plastic deformation of metals, alloys, granular materials, and magnets. The results are relevant for a number of applications, including: materials failure predictions and control from nanodevices to bulk materials, nondestructive materials testing, increased materials stability during processing, improved understanding of jamming and avalanches of granular materials, and long-term security of magnetic information storage. The diverse group of graduate and undergraduate students involved in this project will receive broad interdisciplinary training, and will learn to use modern tools from statistical physics, materials science, mechanical engineering, and mathematics. Collaborations with a network of national and international theorists, experimentalists, materials scientists, engineers, and seismologists will be fostered. Simulation codes will be shared with the broader research community.

技术总结该奖项支持理论研究和教育，将统计物理、材料科学、固体力学、工程学、颗粒力学和冶金学的概念结合起来，以促进和统一对材料对外部应力的响应的理解。最近对小金属或冰晶的剪切响应的实验表明，通过一系列跨越大小范围的位错滑移事件，变形不是平滑的，而是陡然的。同样，密实堆积的颗粒状物质以一系列滑移雪崩响应剪切。在这两种情况下，滑动事件大小的分布在几十年内都是按幂规律描述的。对于一大类不同的材料，相关的幂指数是相同的；它们是“通用的”。这些系统的模拟是有用的，但不同系统之间的联系通常可以更容易地使用分析方法来识别。根据最近的分析，可以评估发生雪崩并在长尺度上表现出相同行为的系统类别的大小。在这个项目中，PI将解析地计算滑移-雪崩统计量与一系列重要的实验调整参数的相关性的预测，例如应变率、应力率、无序度和温度。该方法还将被用来研究在没有驾驶的情况下，低温驱动动力学和高温松弛动力学之间的联系。一个主要目标是扩大和测试最近的分析方法，以便统一对以前被认为无关的非平衡现象的理解。这些方法包括来自相变理论、重整化群、无序系统理论、蒙特卡罗模拟和分子动力学模拟的技术。将这些研究的预测与塑性变形、颗粒材料、磁体的实验以及大规模模拟的结果进行了比较。这项研究的高度跨学科性质为从事这一项目的不同研究生和本科生群体提供了一个理想的学习环境。将促进与国内和国际理论家、实验学家、材料科学家、工程师和地震学家网络的合作。模拟代码将与研究社区共享。这项工作的潜在应用包括：从纳米设备到大宗材料的广泛范围的材料失效预测和控制，无损材料测试，提高对冶金中经常不受欢迎的Portevin-Le Chatelier效应的理解，提高加工过程中的材料稳定性，改善对颗粒材料(如筒仓中的粉末和颗粒)的堵塞和雪崩的理解，以及磁信息存储的长期安全。非技术总结该奖项支持理论研究和教育，以结合统计物理、材料科学、固体力学、工程学、颗粒力学和冶金学的概念，促进和统一对材料如何响应外部应力的理解。许多系统在缓慢推进时会破裂：木材在缓慢弯曲时可能会破裂。同样，小的金属或冰晶通过一系列跨越大小范围的局部滑动事件以相当陡峭的方式变形。在这些滑移事件中，薄弱部位对缓慢增加的外加剪应力作出响应。在更大的范围内，当缓慢的构造运动触发地壳薄弱点的滑动时，大致相同的现象会引发地震。从颗粒材料到磁铁，许多其他系统都出现了类似的失效雪崩。这个项目对这些系统的雪崩统计数据的相似性进行了定量的理解，其中许多系统以前是单独研究的。目标是预测结果和理解可以在多大程度上从一个系统转移到另一个系统。最近，已经开发出强大的数学工具来回答这些问题。这些方法将与计算模拟相结合，并与金属、合金、颗粒材料和磁体的塑性变形实验进行比较。这些结果与许多应用相关，包括：从纳米器件到块状材料的材料失效预测和控制、非破坏性材料测试、提高加工过程中的材料稳定性、改善对颗粒材料堵塞和雪崩的理解，以及磁信息存储的长期安全。参与这个项目的不同的研究生和本科生群体将接受广泛的跨学科培训，并将学习使用统计物理、材料科学、机械工程和数学的现代工具。将促进与国内和国际理论家、实验学家、材料科学家、工程师和地震学家网络的合作。模拟代码将与更广泛的研究社区共享。