Multi-Scale Modeling and Multi-Objective Design Framework for Location-Specific Material Behavior in Additively Manufactured Components

金属材料的增材制造（AM）工艺，即粉末床融合，以及各种粉末进给和钢丝进给系统，正在给制造业带来巨大的变化。通过逐层添加材料实现前所未有的敏捷性，使复杂部件的生产接近净形状。尽管有这样的前景和进步，但由于材料性能和寿命限制性能缺乏一致性，例如，不良的延展性和疲劳性能，增材制造零件的资格和验收受到了影响。这些不一致通常归因于微观结构（形态和缺陷结构）的细微变化，可能是增材制造工艺参数微小扰动的结果。通过实施多管齐下的方法，结合集成计算材料工程（ICME）的创新方法，如基于物理的多尺度建模、多目标设计、材料表征和测试，本研究将通过开发一个强大的框架来解决这一缺点，该框架用于AM工艺制造的结构中特定位置的材料特性和行为。最终，它将为工艺参数与产品性能和寿命之间的联系提供指导，为在关键应用中接受增材制造零件铺平道路。这项研究将促进与ICME相关的科学；通过确定增材制造的来源，促进国家的健康、繁荣和福利；并通过实现战区关键部件的近按需、净形状生产来确保国防安全。与桑迪亚国家实验室和JHU/应用物理实验室的合作伙伴关系将是这项研究的优势。该项目的研究生将接受多学科的培训，学习多尺度建模、设计优化、材料表征和现代制造工艺方面的最新技术。与桑迪亚和JHU/APL的合作也将使他们接触到最先进的技术进步，这将有助于他们的职业发展。两个特定的开发模块将实现增材制造加工金属和合金的多晶-多相微结构。它们是：(i)开发和实现参数化均质本构/损伤模型（phcm），以具有代表性的聚集体微观结构参数或（RAMPs）的形式明确表示微观结构描述符，以及(2)开发基于phcm的稳健设计方法，用于设计结构中特定位置的材料设计，例如通过拓扑优化。此外，基于phcm的模拟很容易估计微观结构变化对结构尺度变量的影响，如应力、应变、强度，甚至延性或疲劳寿命。这将有助于通过拓扑优化等设计方法概念化增材制造加工结构中特定位置材料设计的灵敏度分析。一个多目标函数框架将被纳入识别帕累托前沿，定义可实现的跨属性空间。详细的材料设计工作的结果将是微观结构的结构尺度布局（就坡道而言），以实现强大的、依赖于场地的宏观尺度特性分布。这将指导增材制造工艺参数和路线的选择，以提高结构材料的性能和寿命。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。

Additive manufacturing (AM) processes for metallic materials, namely powder-bed fusion, and various powder-feed and wire-feed systems, are bringing dramatic changes to the manufacturing industry. The unprecedented agility achieved through layer-by-layer material addition is enabling near net-shape production of complex components. Despite this promise and progress, the qualification and acceptance of AM parts have been compromised by the lack of consistency in material behavior and life-limiting properties, e.g., undesirable ductility and fatigue behavior. These inconsistencies are often attributed to subtle, yet characteristic variations in the microstructure (morphology and defect structure), possibly a consequence of small perturbations in the AM process parameters. By implementing a multi-pronged approach incorporating innovative methods of integrated computational materials engineering (ICME), such as physics-based multi-scale modeling, multi-objective design, and materials characterization and testing, this research will address this shortcoming by developing a robust framework for location specific material properties and behavior in structures fabricated by AM processes. Ultimately, it will provide guidance on the links between process parameters and product performance and life, paving the acceptance of AM parts in critical applications. The research will promote the sciences associated with ICME; advance the national health, prosperity, and welfare by establishing the provenance of AM manufacturing; and secure the national defense by enabling near on-demand, net-shape production of critical parts in theaters. Collaborative partnerships with Sandia National Laboratories and JHU/Applied Physics Laboratory will be a strength of this research. Graduate students on this project will undergo multi-disciplinary training in state-of-the-art techniques in multi-scale modeling, design optimization, materials characterization and modern manufacturing processes. The collaboration with Sandia and JHU/APL will also provide them exposure to the most advance technological advancements that will help their professional career development. Two specific developmental modules will be realized for AM processed metals and alloys with polycrystalline-polyphase microstructures. They are: (i) development and implementation of parametrically homogenized constitutive/damage models (PHCMs) with explicit representation of microstructural descriptors in the form of representative aggregate microstructural parameters or (RAMPs), and (2) development of PHCM-based robust design methods for location-specific material design in structures designed, e.g., by topology optimization. Furthermore, PHCM-based simulations readily estimate the effect of variations in the microstructure on structure-scale variables like stresses, strains, strength, and even ductility or fatigue life. This will facilitate sensitivity analysis in location-specific material design in AM processed structures that have been conceptualized by design methods like topology optimization. A multi-objective function framework will be incorporated for identifying a Pareto front, defining the achievable cross-property space. The outcome of the detailed material design undertaking will be a structural-scale layout of the microstructure (in terms of RAMPs) for a robust, site-dependent distribution of macro-scale properties. This will guide the selection of AM processes parameters and routes to improve structure-material performance and life.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.