Towards a New Framework for the Mechanics of Nonequilibrium Continua

走向非平衡连续体力学的新框架

• 批准号: 2054607
• 负责人: Youping Chen
• 金额: $ 42.03万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2054607&HistoricalAwards=false
• 关键词: Towards; New; Framework; Mechanics; Nonequilibrium

Continuum mechanics has been the major theoretical tool for the description and understanding of the mechanics of materials. As science and engineering advance, however, classical continuum mechanics has been shown to be insufficient, e.g., for physical processes involving multiple length/time scales or for dynamic phenomena with unknown thermal transport mechanisms. This research aims to overcome these limitations by developing a new formalism that will enhance the applicability of continuum mechanics to describe multiscale mechanical deformation and thermal transport processes from the atomic to the macroscopic. A simulation tool will be developed based on the formulation and will be freely and broadly disseminated to benefit mechanics and materials communities. In addition, the project will be designed to serve as a scientific training ground for graduate and undergraduate students. The PI will also reach out to students from underrepresented groups as well as students with physical disabilities to provide them with hands-on research experiences from which they may launch their careers. Different from the top-down formulation of classical continuum mechanics, this research will employ a bottom-up formalism to rederive the field representation of balance laws. The formulation will build on a concurrent atomistic and continuum description of materials by including the atomic degrees of freedom embedded within each material point; this will allow atomic-scale discontinuities and thermal fluctuations to be explicitly included in the formulation. The Theory of Distributions will be used as the mathematical tool for the formulation, which will provide a rigorous solution to the mathematical difficulties in linking particle and field descriptions of physical behavior involving discontinuous or singular functions. The research will also redefine temperature as a derived quantity, thus enabling the descriptions of all the field quantities in continuum mechanics to be fully consistent with those measured in experiments or calculated from atomistic simulations. In addition, a simulation tool will be developed, demonstrated, and validated by reproducing two highly nonequilibrium processes that are both temperature- and size-dependent: heteroepitaxial growth and thermally activated dislocation motion. It is expected that this research will lead to a new framework for the mechanics of continua that can predict highly non-equilibrium deformation processes and phenomena, as well as reveal the underlying mechanisms, with no empirical rules or parameters other than an interatomic potential. This project is co-funded by the Mechanics of Materials and Structures (MOMS) program in the Division of Civil, Mechanical and Industrial Innovation (CMMI) and the Thermal Transport Processes (TTP) program in the Division of Chemical, Bioengineering, Environmental and Transport Systems (CBET).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.

连续介质力学是描述和理解材料力学的主要理论工具。然而，随着科学和工程的进步，经典连续介质力学已被证明是不够的，例如，用于涉及多个长度/时间尺度的物理过程或用于具有未知热传输机制的动态现象。本研究的目的是克服这些局限性，通过开发一种新的形式主义，将提高连续介质力学的适用性，以描述从原子到宏观的多尺度机械变形和热输运过程。 将根据该公式开发一个模拟工具，并将免费广泛传播，以造福力学和材料界。此外，该项目将被设计为研究生和本科生的科学培训基地。PI还将接触来自代表性不足群体的学生以及身体残疾的学生，为他们提供实践研究经验，以便他们可以从中开始自己的职业生涯。 与经典连续介质力学自上而下的表述方式不同，本研究将采用自下而上的形式主义来重新推导平衡定律的场表示。该配方将建立在一个并发的原子和连续描述的材料，包括原子的自由度嵌入在每个材料点，这将允许原子尺度的不连续性和热波动被明确地包括在配方中。 分布理论将被用来作为数学工具的制定，这将提供一个严格的解决方案的数学困难，在连接粒子和场描述的物理行为，涉及不连续或奇异函数。这项研究还将重新定义温度作为一个派生量，从而使连续介质力学中所有场量的描述与实验测量或原子模拟计算的结果完全一致。此外，模拟工具将被开发，演示和验证，通过复制两个高度非平衡的过程，都是温度和尺寸依赖：异质外延生长和热激活位错运动。预计这项研究将导致一个新的框架，可以预测高度非平衡变形过程和现象，以及揭示潜在的机制，没有经验规则或参数以外的原子间的潜力。该项目由土木，机械和工业创新（CMMI）部门的材料和结构力学（MOMS）计划以及化学，生物工程，环境和运输系统（CBET）该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的评估被认为值得支持。影响审查标准。

项目成果

Resonant interaction between phonons and PbTe/PbSe (001) misfit dislocation networks

声子与 PbTe/PbSe (001) 失配位错网络之间的共振相互作用

• DOI: 10.1016/j.actamat.2022.118143
• 发表时间: 2022
• 期刊: Acta Materialia
• 影响因子: 9.4
• 作者: Li, Yang;Zheng, Zexi;Diaz, Adrian;Phillpot, Simon R.;McDowell, David L.;Chen, Youping
• 通讯作者: Chen, Youping

A parallel algorithm for the concurrent atomistic-continuum methodology

并发原子连续体方法的并行算法

• DOI: 10.1016/j.jcp.2022.111140
• 发表时间: 2022
• 期刊: Journal of Computational Physics
• 影响因子: 4.1
• 作者: Diaz, Adrian;Gu, Boyang;Li, Yang;Plimpton, Steven J.;McDowell, David L.;Chen, Youping
• 通讯作者: Chen, Youping