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，这个振动辅助激光小孔焊接项目促进了国家的繁荣和福利；它也有许多国防应用，以确保该项目的国防安全。焊接生产率和性能的任何改善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，与弧焊、电阻焊等传统焊接工艺相比，可以将焊接速度提高数十倍甚至数百倍。然而，激光焊接会遇到几个问题，包括接头中的高气孔率、粗大的颗粒和脆性的金属间化合物，所有这些都会降低性能。该学院早期职业发展计划(CALEAR)项目专注于一种名为振动辅助激光小孔焊接(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。如果研究成功，将大大促进对V-LKW复杂现象的科学理解，并促进这一新工艺在制造业(特别是汽车和航空航天部门)的应用，以提高焊接生产率和性能。这个项目的教育目标是让学生参与并为现代制造技术中的智力挑战做好准备。面向高中生的外展活动将培养他们对制造技术的兴趣，并鼓励他们将工程学作为未来的职业。这个职业项目将专注于一种新的振动辅助激光小孔焊接(V-Lkw)工艺。研究的目的是验证这样一种假设，即通过减少气孔、细化晶粒和金属间化合物还原的机制可以显著改善V-Lkw接头的性能，所有这些机制都是激光振动方向、幅度和频率的函数。将使用过程中时间分辨观察技术、后处理组织/力学表征方法和多物理数值模型来确定V-LKW的过程-结构-性能关系，并了解V-LKW的基本物理。如果成功，该项目将促进我们对激光-物质相互作用、小孔动力学行为、振动产生/传输、多相热流体流动以及V-LKW中的凝固现象的理解。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。外展和教育活动将改善犹他大学的制造业科学和工程教育，吸引更多的高中生、大学生和少数族裔学生选择工程和制造业职业，并加强该大学与当地社区的联系。研究成果将通过期刊/会议出版物和与行业的互动及时传播。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.