Multiscale Structure-Mechanical Property Investigation of Additive Manufactured Components for Development of a Reliable Qualification Method

增材制造（也称为3D打印）现在能够生产/建造足够坚固的复杂形状金属部件，用于结构应用。 然而，传统制造的标准鉴定方法不适用于增材制造零件，因为这些零件的机械行为与传统方法制造的零件有根本的不同。因此，本研究的目标是基于经验证的计算机模拟和非破坏性评估技术的组合方法，为增材制造组件开发一种高度可靠，低成本和高效的鉴定方法。这种鉴定方法将可能导致增材制造的更广泛采用，并将影响需要复杂，高价值，时间敏感和定制产品和原型的应用，如汽车和航空航天零件（即，复杂的设计），损坏的部件更换（即，时间敏感的），和医疗植入物（即，高度定制化）。 学生在这个项目中获得的技能和知识将为他们在确保美国在未来几代人制造工程领域的领导地位方面发挥积极作用做好准备。 为了实现其目标，该项目有以下目标：1）表征多个长度尺度上的关键微观结构特征和机械性能; 2）开发概率本构模型以捕获亚微米机械行为; 3）基于各种无损评估技术的微观结构数据开发宏观模型;以及4）在复杂部件上测试鉴定方法。这项研究解决了增材制造结构部件的可靠鉴定中的一个具有挑战性的问题，这些部件的局部微观结构和机械行为在同一部件的不同构造之间可能会有很大差异。 X射线微计算机断层扫描的使用保证了被扫描材料中的任何微尺度缺陷都可以被检测到，从而可以直接模拟设计部件中的机械行为。通过多尺度的调查，本构模型将开发捕捉缺陷，晶粒尺寸和残余应力的机械效果。因此，将各种无损评估技术与基于物理的建模相结合，将为增材制造组件提供快速，可靠和低成本的鉴定方法。

Additive manufacturing (also called 3D printing) is now capable of producing/building complex-shaped metal components strong enough for structural applications. However, standard qualification methods for traditional manufacturing are not suitable for additive manufactured parts because the mechanical behavior of these parts is fundamentally different from those made by traditional means. Hence, the goal of this research is to develop a highly reliable, low-cost, and efficient qualification method for additive manufactured components based on a combined approach of validated computer simulations and non-destructive evaluation techniques. This qualification method will potentially lead to much wider adoption of additive manufacturing and will impact applications requiring complex, high value, time-sensitive, and customized products and prototypes such as automobile and aerospace parts (i.e., complex designs), broken part replacement (i.e. time-sensitive), and medical implants (i.e., highly customized). The skills and knowledge the students gain in this project will prepare them for active roles in securing the the United States' leadership in manufacturing engineering for future generations. To achieve its goal, this project has the following objectives: 1) Characterize key microstructure features and mechanical properties across multiple length scales; 2) Develop a probabilistic constitutive model to capture sub-micron mechanical behavior; 3) Develop a macroscopic model based on microstructure data from various non-destructive evaluation techniques; and 4) Test the qualification method on a complex part. This research tackles a challenging problem in the reliable qualification of additive manufactured structural components whose local microstructure and mechanical behavior may vary widely among different builds of the same component. The utilization of X-ray micro computed tomography guarantees that any microscale flaws in the materials being scanned can be detected so that direct simulation of their mechanical behavior in the design component is possible. Through the multiscale investigation, a constitutive model will be developed to capture the mechanical effects of flaws, grain size, and residual stress. The integration of various nondestructive evaluation techniques with physics-based modeling will thus enable a rapid, reliable, and low-cost qualification method for additive manufactured components.