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

University Of Utah, Salt Lake City UT

Investigators

Abstract

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.