Methods for Atomistic Input into Initial Yield and Plastic Flow Criteria for Nanocrystalline Materials

纳米晶材料初始屈服强度和塑性流动准则的原子输入方法

• 批准号: 1030103
• 负责人: David McDowell
• 金额: $ 27.58万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1030103&HistoricalAwards=false
• 关键词: Methods; Atomistic; Input; into; Initial

The objective of this research is to employ molecular dynamics simulations to shed light on the proper forms for the constitutive description of stress-state dependent inelastic deformation modes for some nanocrystalline metals, including grain boundary shuffling/sliding, grain boundary dislocation nucleation, absorption and desorption, and free volume exchange of grain boundaries with triple junctions. The research approach will emphasize methods to simulate and quantitatively characterize distinct contributions of competing deformation mechanisms of grain boundary sliding, grain boundary dislocation nucleation, absorption and desorption, and grain core dislocation activity in three-dimensional nanocrystalline ensembles. To accomplish the above goals, the research integrates concepts and methods that bridge between materials science/physics and the engineering sciences, in particular mechanics of materials.The broader outcomes of this project will be used to gain fundamental new understanding of behavior of nanocrystalline materials, which can be used to inform improved continuum models of nanocrystalline materials with competing modes of deformation; to motivate proper, atomistically-consistent forms of yield surfaces in which to embed continuum models, including tension-compression asymmetry and general stress state effects; and to estimate the spectra of activation energy and volumes for both bulk- and grain boundary-mediated inelastic deformation modes, useful for modeling kinetics at long time scales. The research will provide advanced training for both graduate and undergraduate students. Moreover, outreach activities will be conducted to motivate high-school students to pursue careers in engineering research and education.

这项研究的目的是利用分子动力学模拟来阐明适当的形式，以构成某些纳米晶金属的应力依赖性依赖性的非弹性变形模式，包括晶粒边界避免/滑动，晶粒边界脱位成核，吸收和吸收，吸收和脱水，以及与晶粒边界的自由交换，并与三合一结合。该研究方法将强调模拟和定量表征晶界滑动，晶界边界脱位核，吸收和解吸的竞争变形机制的不同贡献以及三维纳米晶体集合中的晶核位错活性。为了实现上述目标，该研究整合了材料科学/物理学与工程科学之间桥接的概念和方法，特别是材料的机制。该项目的更广泛的结果将用于对纳米晶体材料的行为进行基本的新理解，这些材料可用于纳米晶体材料的改进材料的改进材料，以竞争竞争力的模式为竞争力的材料提供依据，以供竞争性模态。激励适当的，原子矛盾的屈服表面形式，其中嵌入连续模型，包括张力压缩不对称和一般应力状态效应；并估算大量和晶界介导的非弹性变形模式的激活能和体积的光谱，可用于长时间尺度建模动力学。该研究将为研究生和本科生提供高级培训。此外，将进行外展活动，以激发高中生从事工程研究和教育的职业。