Collaborative Research: Coupled Explicit Thermodynamics of Plasticity - An Innovative Model for Twinning Crystals

合作研究：耦合显式塑性热力学——孪生晶体的创新模型

• 批准号: 2051355
• 负责人: Curt Bronkhorst
• 金额: $ 31.91万
• 依托单位: University of Wisconsin-Madison
• 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 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2051355&HistoricalAwards=false
• 关键词: Collaborative; Research; Coupled; Explicit; Thermodynamics

Most metallic materials are polycrystalline in nature and behave as aggregate composites of single crystals as the basic building block. Metallic materials generally deform elastically by atomic bond distortion or plastically by atomic bond rearrangement. Plastic deformation takes place by the mechanisms of dislocation motion and deformation twinning. Dislocations are atom sized features which move by applied stress and have been relatively well studied and are described by many advanced theories. Deformation twins are single crystal sized features and are not well understood or represented by theories of deformation. This award supports fundamental study of deformation twinning and overcoming limitations to modeling of this plasticity mechanism. The new knowledge and computational capability will have a broad range of applications to advanced manufacturing, structure survivability, and transportation. In addition, the project will support the education of graduate and undergraduate students in the areas of computational micromechanics, materials science, and crystal plasticity. The collaborative nature of the award will also afford the students the opportunity to engage across the two campuses.Plasticity in metallic materials is mediated by both dislocation slip and deformation twinning. The disparity in characteristic length between the two mechanisms is a limitation to crystal plasticity finite element simulation of polycrystals as deformation twins cannot be represented by volume average. The objective of this project is to develop a computational framework for the explicit representation of deformation twins based upon an embedded weak discontinuity technique. The embedded weak discontinuity is driven by single crystal theory which accounts for twin nucleation, propagation, and growth within a consistent thermodynamic and physical basis. Dislocation slip will also be represented with a thermally activated based theory and will allow slip to occur in both twinned and untwinned regions. The interaction of dislocations with the twin boundaries will also be modelled during the twin growth phase. This project will focus upon the model material of high-purity titanium. Validation experiments will be conducted on large grain samples to allow for detailed characterization. These deformation experiments will be conducted at different initial temperatures and sample temperatures will be measured during deformation to evaluate the model prediction of the Taylor-Quinney factor.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.

大多数金属材料本质上是多晶的，并且表现为作为基本构建块的单晶的聚集复合物。金属材料通常通过原子键变形而弹性变形，或通过原子键重排而塑性变形。塑性变形是通过位错运动和形变孪晶机制发生的。位错是原子大小的特征，其通过施加的应力而移动，并且已经被相对较好地研究，并且由许多先进的理论描述。变形孪晶是单晶尺寸的特征，并且没有被变形理论很好地理解或表示。该奖项支持变形孪晶的基础研究，并克服这种塑性机制建模的局限性。新的知识和计算能力将在先进制造、结构生存性和运输方面有广泛的应用。此外，该项目将支持计算微观力学、材料科学和晶体塑性领域的研究生和本科生的教育。该奖项的合作性质也将为学生提供跨两个校区参与的机会。金属材料的塑性由位错滑移和变形孪晶介导。这两种机制之间的特征长度的差异是一个限制晶体塑性有限元模拟的多晶体变形孪晶不能表示的体积平均。这个项目的目标是开发一个计算框架的基础上嵌入弱不连续技术的变形孪晶的显式表示。嵌入的弱不连续性是由单晶理论驱动的，该理论在一致的热力学和物理基础上解释了孪晶成核、传播和生长。位错滑移也将表示与热激活的理论，并将允许滑移发生在孪晶和非孪晶区域。位错与孪晶界的相互作用也将在孪晶生长阶段建模。本项目将重点研究高纯钛的模型材料。将对大颗粒样品进行验证实验，以进行详细的表征。这些变形实验将在不同的初始温度下进行，并在变形过程中测量样品温度，以评估泰勒-昆尼因子的模型预测。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。