GOALI/Collaborative Research: Understanding Multiscale Mechanics of Cyclic Bending under Tension to Improve Elongation-to-Fracture of Hexagonal Metals

GOALI/合作研究：了解张力下循环弯曲的多尺度力学，以提高六方金属的断裂伸长率

• 批准号: 2147126
• 负责人: David Fullwood
• 金额: $ 31.47万
• 依托单位: Brigham Young University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2147126&HistoricalAwards=false
• 关键词: GOALI; Collaborative; Research; Understanding; Multiscale

At the core of various strategies to reduce consumption of fossil fuels in the transportation industry is the goal to reduce structural weight, generally termed ‘lightweighting’. Certain metals, such as titanium and magnesium, have crystal structures known as hexagonal closed-packed (HCP), which contribute to superior strength-to-weight ratios. However, HCP metals often do not have the required ductility to form them into the desired shapes at room temperature. Instead of heating the material, with the accompanying expense, this Grant Opportunities for Academic Liaison with Industry (GOALI) research project will implement, characterize, and model a novel incremental forming process called ‘continuous bending under tension’ (CBT). The goal of the project is to double the formability of HCP metals at room temperature. By working with GOALI partner Boeing, the team will solve forming problems that are of immediate value to industry while enabling the lightweighting of aerospace structures. Furthermore, the modeling and materials characterization tools will be encapsulated in open-source software for free access to the entire scientific community. The students involved in the research will gain knowledge and understanding of industrial challenges through internship opportunities. An essential part of the project will be the instigation of an outreach program called Capstone Connect. An online forum will be created specifically for senior high-school students to connect with academic and industrial specialists as they tackle their final year Capstone projects. Not only will students gain deeper insights into engineering design projects, but the interactions will enlighten them concerning future STEM careers. While the ability to increase elongation-to-failure (ETF) in steels, for example, via CBT has been demonstrated, application to HCP metals has been limited. Furthermore, a deeper understanding of the mechanics behind the improved ductility is required to both optimize CBT process conditions and to transfer the underlying ideas into practical forming operations. This project will utilize high resolution digital image correlation (HRDIC) and high-resolution electron backscatter diffraction (HREBSD) to observe local slip activity, strain gradients, dislocation rearrangement, substructure development and associated back stresses that play a role in the remarkable increase in ETF during CBT. The experimental campaign will serve to inform and validate a novel non-local crystal plasticity finite element (CPFE) model at the critical mechanism length-scale, enabling understanding of mechanics in CBT to improve ETF of HCP metals. This combined experimental and modeling effort will provide unprecedented insights into CBT, and the practical success of the project will be demonstrated via the forming of a leading-edge titanium component with Boeing.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.

减少运输行业化石燃料消费的各种策略的核心是减少结构重量的目标，通常称为“轻量级”。某些金属（例如钛和镁）具有称为六角形封闭式包装（HCP）的晶体结构，这有助于优势强度与重量比。但是，HCP金属通常没有所需的延展性将它们在室温下形成所需的形状。该学术联络人与行业联络（Goali）研究项目的赠款机会无需加热材料，而不是加热材料，将实施，表征和建模一种新型的增量成型过程，称为“张力下连续弯曲”（CBT）。该项目的目的是使HCP金属在室温下的形成性加倍。通过与Goali合作伙伴波音公司合作，该团队将解决对行业具有直接价值的问题，同时实现航空航天结构的轻巧。此外，建模和材料表征工具将封装在开源软件中，以免费访问整个科学界。参与研究的学生将通过实习机会获得对工业挑战的知识和理解。该项目的重要组成部分将是一个名为Capstone Connect的外展计划的煽动。在线论坛将专门为高中生的高中生与学术和工业专家建立联系，以解决他们的最后一年的顶峰项目。学生不仅会对工程设计项目获得更深入的见解，而且互动会启发他们与未来的STEM职业有关。例如，尽管已经证明了通过CBT增加钢中伸长到失败（ETF）的能力，但在HCP金属上的应用仍受到限制。此外，需要对改进的延展性背后的机制有更深入的了解，以优化CBT过程条件并将基础思想转移到实际的形成操作中。该项目将利用高分辨率的数字图像相关性（HRDIC）和高分辨率电子反向散射衍射（HREBSD）来观察局部滑动活性，应变梯度，脱位重排，子结构的发展以及相关的背应力，在CBT期间ETF的显着增加中起着显着增加的作用。实验运动将有助于在关键机理长度尺度上为新型的非本地晶体可塑性有限元（CPFE）模型提供信息，从而使对CBT机制的理解能够改善HCP金属的ETF。这项结合的实验和建模工作将为CBT提供前所未有的见解，该项目的实际成功将通过与波音公司形成领先的钛合金组成。这一奖项反映了NSF的法定任务，并通过使用该基金会的知识分子优点和广泛影响来评估NSF的法定任务，并被认为是诚实的支持。