CAREER: Vibration-Assisted Laser Keyhole Welding to Improve Joint Properties

焊接关键行业约占美国国内生产总值（GDP）的三分之一，因此这个关于振动辅助激光锁眼焊接的项目促进了国家的繁荣和福利；它也有许多国防应用，使该项目保障国防。焊接生产率和性能的任何改进都可能为国家节省数十亿美元。激光焊接是一种很有前途的焊接工艺，与电弧焊、电阻焊等传统焊接工艺相比，可将焊接速度提高数十倍甚至数百倍。然而，激光焊接会遇到一些问题，包括高孔隙率、粗颗粒和脆性金属间化合物的接头，所有这些都会降低性能。这个教师早期职业发展计划（Career）项目聚焦于一种称为振动辅助激光锁眼焊接（V-LKW）的新工艺，旨在研究激光振动如何帮助解决激光焊接中的上述问题。实验和数值模拟将同时用于研究V-LKW的基本物理特性。这项研究如果成功，将极大地促进对V-LKW复杂现象的科学理解，并促进这种新工艺在制造业（特别是汽车和航空航天领域）的应用，以提高焊接生产率和性能。该项目的教育目标是让学生为现代制造技术中的智力挑战做好准备。为培养高中生对制造技术的兴趣，鼓励他们探索工程作为未来的职业，将开展外展活动。该CAREER项目将重点研究一种新型振动辅助激光锁眼焊接（V-LKW）工艺。本研究的目的是验证以下假设：通过减少孔隙率、细化晶粒、减少金属间化合物等机制，可以显著改善V-LKW接头的性能，这些机制都是激光振动方向、振幅和频率的函数。过程中时间分辨观测技术、过程后微观结构/力学表征方法和多物理场数值模型将用于识别V-LKW的过程-结构-性能关系，并了解V-LKW的基本物理特性。如果成功，该项目将推进我们对激光-物质相互作用、钥匙孔动力学行为、振动产生/传递、多相热流体流动和V-LKW凝固现象的理解。这项研究将有助于提高许多产品的焊接生产率和接头性能，包括但不限于汽车、热管理设备、电子设备和医疗设备。推广和教育活动将改善犹他大学的制造科学和工程教育，吸引更多的高中、大学和少数民族学生选择工程和制造业的职业，并加强大学与当地社区的联系。研究成果将通过期刊/会议出版物和与工业界的互动及时传播。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。

Welding-critical industries represent about one-third of the Gross Domestic Product (GDP) of the United States, and as such this project on vibration-assisted laser keyhole welding advances the national prosperity and welfare; it also has numerous defense applications so that this project secures the national defense. Any improvements in welding productivity and performance can potentially save billions of dollars for the country. Laser welding is a promising process that can improve the welding speed by tens and even hundreds of times compared with conventional welding processes such as arc welding and electric resistance welding. However, laser welding can suffer from several problems, including high porosity, coarse grains, and brittle intermetallic compounds in the joints, all of which can reduce performance. This Faculty Early Career Development Program (CAREER) project is focused on a novel process called Vibration-assisted Laser Keyhole Welding (V-LKW) and aims to study how the laser vibration will help to solve the aforementioned problems in laser welding. Experimentation and numerical modeling will be used simultaneously to investigate the fundamental physics in V-LKW. The research, if successful, will significantly advance scientific understanding of the complex phenomena in V-LKW, and promote the applications of this novel process in the manufacturing industry (especially the automotive and aerospace sectors) for the improvement of welding productivity and performance. The educational objective of this project is to engage and prepare students for the intellectual challenges in modern manufacturing technologies. Outreach activities to high school students will be conducted to cultivate their interests in manufacturing technology and encourage them to explore engineering as their future careers.This CAREER project will focus on a novel Vibration-assisted Laser Keyhole Welding (V-LKW) process. The research objective is to test the hypothesis that the properties of V-LKW joints can be significantly improved through the mechanisms of porosity reduction, grain refinement, and intermetallic reduction, all of which are functions of the vibration direction, amplitude, and frequency of the laser. In-process time-resolved observation techniques, post-process microstructural/mechanical characterization methods, and a multi-physics numerical model will be used to identify the process-structure-property relationship of V-LKW and understand the fundamental physics in V-LKW. If successful, this project will advance our understanding of laser-matter interaction, keyhole dynamic behavior, vibration generation/transmission, multi-phase thermo-fluid flow, and solidification phenomena in V-LKW. The research will enable the improvement of welding productivity and joint properties in the manufacturing of many products, including but not limited to automobiles, thermal management devices, electronic devices, and medical devices. The outreach and education activities will improve the education of manufacturing science and engineering at the University of Utah, attract more high school, college, and minority students to choose careers in engineering and manufacturing, and strength the university's connection to local communities. Research results will be disseminated in a timely manner through journal/conference publications and interactions with industries.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.