CAREER: Bridging Research & Education in Delineating Fatigue Performance & Damage Mechanisms in Metal Fused Filament Fabricated Inconel 718

目前用于快速制造结构部件的金属增材制造/3D打印技术（即激光粉末床熔融、粘合剂喷射和直接能量沉积）非常昂贵，限制了它们在更大范围内的使用。另外，金属熔丝制造增材制造技术，将金属粉末熔化并挤压在塑料丝中，为快速零件生产提供了一种低成本的方法，并具有安全性和易于操作的额外好处。这个学院早期职业发展（Career）奖将支持通过描述金属熔丝制造的镍基高温合金的整体疲劳性能和控制失效机制来推进力学领域的研究，这些金属熔丝制造的镍基高温合金用于航空、航天、能源、推进和汽车行业的结构部件。与该技术相关的限制（即收缩、孔隙、微观结构缺陷等）的缓解将通过后处理技术进行评估，包括它们对影响疲劳性能的作用。将研究成果与加强教育相结合，为中学生开展金属熔丝制造增材制造技术的教育推广活动，并将基于项目的学习活动纳入学术课程。研究机会和对代表性不足的少数民族的专业培训将是研究的一部分，包括通过加速学士学位到硕士学位（4+1）计划推动本科到研究生教育的过渡，以及建立一个研究研讨会，以提高公众的科学素养。CAREER奖支持基础研究，以提高对低成本金属熔丝制造的Inconel 718所表现出的力学的理解，这些材料经受了各种疲劳测试（即轴向、旋转梁和扭转疲劳），反映了结构部件所经历的真实机械负载环境。研究了疲劳载荷条件和微观组织缺陷分布对疲劳失效的影响。将探讨构建取向和后处理技术在缓解这些缺陷以增强疲劳性能方面的作用。疲劳断口表面分析、微观结构演变和通过该技术引入的微观结构缺陷评估将使用材料表征技术/显微镜相结合的方式进行。预计这项研究可以为低成本增材制造的下一个前沿领域铺平道路，以设计具有满足基本机械性能功能要求的结构部件。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。

Current metal additive manufacturing/3D printing technologies (i.e., laser powder bed fusion, binder jetting, and direct energy deposition) for rapid manufacturing of structural components are extremely expensive, limiting their use on a broader scale. Alternatively, metal fused filament fabrication additive manufacturing technology, which melts and extrudes metal powder bound in a plastic filament, provides a low-cost approach for rapid part production, with the added benefits of safety and ease of operation. This Faculty Early Career Development (CAREER) award will support research that advances the field of mechanics by delineating the overall fatigue performance and governing failure mechanisms exhibited by metal fused filament fabricated nickel-based superalloy, used in structural components within the aviation, space, energy, propulsion, and automotive industries. Mitigation of limitations (i.e., shrinkage, porosity, microstructural defects etc.) associated with this technology will be assessed through post-processing techniques, including their role on impacting fatigue performance. Integration of research findings with educational enhancement will be used to develop educational outreach activities for middle and high school students on metal fused filament fabrication additive manufacturing technology, along with incorporation of project-based learning activities within the academic curriculum. Research opportunities and professional training of under-represented minorities will be part of the study, including propelling undergraduate to graduate educational transition through an Accelerated B.S. to M.S. (4+1) program along with establishment of a research symposium to enhance public scientific literacy. This CAREER award supports fundamental research to enhance understanding of the mechanics exhibited by low-cost metal fused filament fabricated Inconel 718, subject to a variety of fatigue tests (i.e., axial, rotating beam, and torsional fatigue), reflective of the realistic mechanical loading environments experienced by structural components. The study intends to investigate the interaction of fatigue loading condition and microstructural defect distribution on fatigue failure. The role of build orientation and post-processing techniques on mitigation of these defects for enhanced fatigue performance will be explored. Fatigue fracture surface analysis, microstructural evolution, and assessment of microstructural defects introduced through this technology will be performed using a combination of material characterization techniques/microscopy. It is anticipated that this study could pave the next frontier in low-cost additive manufacturing to design structural components with the potential to meet basic mechanical performance functional requirements.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.