Multi-Scale Experimental and Computational Investigation of Microscale Origins of Ductile Failure

在使用中，金属暴露在无数的情况下，韧性断裂导致早期失效。该奖项支持基础研究，以了解工程金属中这种失效类型的起源。通过实验、计算模拟和数据科学方法，该研究旨在确定金属微观结构的关键特征与它们在广泛的现实载荷条件下的失效倾向之间的联系。该研究成果将使现有材料的更有效利用和新材料的定制微结构设计成为可能，从而实现卓越的损伤容忍度、能量吸收或断裂性能。这些特性是提高组件安全性、节约成本和减少环境足迹的关键。该奖项将通过学生研究为本科生和研究生提供教育和培训，并将通过教师/学生交流计划和实践研讨会，建立与克拉克亚特兰大大学现有的合作伙伴关系。本研究的主要目标是定量确定多轴应力状态如何被局部微观结构（晶粒取向错误和邻域）改变，促进位错结构的发展，从而直接导致金属中空洞成核的条件。虽然已知破坏应变的工程测量随应力状态而变化，但局部微观结构特征如何改变应力状态从而导致破裂起裂尚不清楚。研究人员将使用实验测量（原位扫描电子显微镜和同步加速器x射线衍射）和计算模拟（晶体塑性和位错动力学），通过先进的回归方法进行分析，以确定材料、微观结构和应力状态特征对金属延性衰竭的相对重要性和/或耦合。通过揭示这些影响相互交织的作用，这项研究将使未来发展新的断裂标准，包括明确的微观结构描述，促进当前合金的充分利用和优质材料的开发。该奖项反映了美国国家科学基金会的法定使命，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。

Metals are exposed to countless scenarios in service in which ductile fracture leads to early failure. This award supports fundamental research to understand the origins of this failure type in engineering metals. Using experiments, computational simulations, and data science approaches, the research aims to identify links between key features in the microstructure of metals and their propensity for failure under a wide range of real-world loading conditions. The research findings will enable the more efficient use of existing materials and the design of new materials with tailored microstructures for superior damage tolerance, energy absorption, or fracture performance. These features are key to enabling increased component safety, cost savings, and reduced environmental footprint. The award will provide education and training at undergraduate and graduate levels through student research and will build on an existing partnership with Clark Atlanta University through a faculty/student exchange program and hands-on workshops.The primary goal of this research is to quantitatively determine how multiaxial stress states, modified by local microstructure (grain misorientation and neighborhoods), promotes the development of dislocation structures that result in conditions directly preceding void nucleation in metals. While it is known that engineering measures of failure strain vary with stress state, how local microstructural features alter stress states resulting in fracture initiation is not well understood. The researchers will use experimental measurements (in situ scanning electron microscopy and synchrotron X-ray diffraction) and computational simulations (crystal plasticity and dislocation dynamics) analyzed through advanced regression methods to determine the relative importance and/or coupling of material, microstructural, and stress state features on ductility exhaustion of metals. By unraveling the intertwined roles of these effects, this research will enable the future development of novel fracture criteria that include explicit microstructural descriptions, facilitating the full use of current alloys and the development of superior materials.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.