DMREF: Designing Microstructure for Engineering Toughness

该项目汇集了一个跨学科的团队，他们的愿景是利用数字制造方法，包括3D打印和喷墨打印，来合成具有特殊机械性能的结构材料。人们早就知道，材料的精细结构——微观结构——会影响机械性能，这在材料加工和制造复合材料中都得到了利用。然而，这种努力在历史上一直局限于可以探索的微观结构范围。这里的愿景是通过采用数字和增材制造方法来克服这一限制，这些方法已经出现并在很大程度上被用作原型制作工具，以制造具有卓越机械性能的结构材料。研究人员特别关注断裂，因为它在工程上的重要性，也因为它提出了深刻的科学问题。该项目将在跨学科环境中为博士生和本科生研究人员的研究参与提供培训，并为K-12学生提供新的机会，并在代表性不足的群体中促进STEM教育。断裂是一个自由不连续问题，此类问题的均质化和优化设计是一个长期存在的智力挑战。在这个项目中，将寻求新的理论和计算方法来应对这一挑战。自由边界问题将采用变分断裂场方法进行正则化，并在新的冲浪边界条件下研究裂纹扩展。通过对轨迹进行参数优化和拓扑优化，实现微结构的优化设计。创新的方法将被探索，以适应原型方法的结构材料的合成与设计的微结构。虽然塑料的3D打印和相关方法已经获得了相当大的关注，但这里将采用这些策略来合成适当尺寸的结构陶瓷。最后，新兴的实验方法，包括数字图像相关、x射线计算机断层扫描和共聚焦显微镜，将被用于对非均质材料复杂断裂过程的理论研究提供见解和验证。

This project brings together an interdisciplinary team with the vision of exploiting digital manufacturing methods, including 3D printing and ink-jet printing, to synthesize structural materials with exceptional mechanical properties. It has long been understood that the fine-scale structure of materials -- the microstructure -- can affect mechanical properties, and this has been exploited in both materials processing and in creating composite materials. However, such effort has historically been limited in the range of microstructures that could be explored. The vision here is to overcome this limitation by adapting methods of digital and additive manufacturing -- which emerged and have largely been used as tools for prototyping -- to make structural materials with superior mechanical performance. The investigators specifically focus on fracture because of its existential engineering importance and because it raises deep scientific questions. This project will provide for the training through research involvement of doctoral students as well as undergraduate researchers in an interdisciplinary setting, and a new opportunity for engaging K-12 students and for promoting STEM education amongst underrepresented groups.Fracture is a free discontinuity problem, and homogenization and optimal design of such problems is a long-standing intellectual challenge. In this project, new theoretical and computational approaches addressing this challenge will be pursued. The free boundary problem will be regularized using a variational fracture field approach, and crack propagation will be studied subject to a new surfing boundary condition. Optimal design of the microstructure will be pursued through parametric optimization and topology optimization applied to trajectories. Innovative approaches will be explored to adapt prototyping methods to the synthesis of structural materials with designed microstructures. While 3D printing and related methods for plastics have gained considerable attention, these strategies will be pursued here to synthesize structural ceramics at the appropriate size scales. Finally, emerging experimental methods, including digital image correlation, X-ray computed tomography, and confocal microscopy, will be employed to provide both insight into and validation of the theoretical studies of the complex process of fracture in heterogeneous materials.