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

金属在使用中暴露在无数种情况下，在这些情况下，韧性断裂会导致早期失效。该奖项支持基础研究，以了解工程金属中这种失效类型的根源。利用实验、计算模拟和数据科学方法，这项研究旨在确定金属微观结构的关键特征与它们在广泛的真实世界加载条件下的失效倾向之间的联系。研究结果将使现有材料得到更有效的利用，并设计具有定制微结构的新材料，以实现卓越的损伤容限、能量吸收或断裂性能。这些功能是提高组件安全性、节约成本和减少环境影响的关键。该奖项将通过学生研究提供本科生和研究生水平的教育和培训，并将通过教职员工/学生交流计划和动手工作室建立与克拉克亚特兰大大学的现有合作伙伴关系。这项研究的主要目标是定量确定由局部微结构(颗粒取向偏差和邻域)修正的多轴应力状态如何促进位错结构的发展，这些结构导致直接导致金属中空洞形核的条件。虽然已知破坏应变的工程测量随应力状态而变化，但局部微结构特征如何改变应力状态从而导致断裂还不是很清楚。研究人员将使用实验测量(原位扫描电子显微镜和同步辐射X射线衍射)和通过高级回归方法分析的计算模拟(晶体塑性和位错动力学)来确定材料、微观结构和应力状态特征对金属延性耗尽的相对重要性和/或耦合。通过解开这些影响的相互交织的作用，这项研究将使新的断裂标准的未来发展成为可能，其中包括明确的微观结构描述，促进现有合金的充分使用和优质材料的开发。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.