SGER: Synergistic and Inherently Stable Laser/Plasma-Jet Welding Processes: Proof of Concept

这笔SGER赠款旨在开发一种试验系统，通过结合光纤激光器和等离子射流来实现协同和稳定的深熔焊接。这一试验系统的成功在很大程度上依赖于实时等离子体传感器以及光纤激光器和等离子体射流的集成。为了开发这种实时等离子体传感器，高速摄影系统将与用于图像处理的高性能计算系统集成在一起，帧速率高达20万fps。这一高速摄影系统允许PI观察小孔和等离子体喷射的振荡，以验证和改进新的等离子体传感器阵列的设计。该观测还允许对目前正在开发的激光/等离子体喷射过程的严格数学模型进行验证。其关键技术在于中等功率的激光光束和具有特殊喷嘴设计的等离子体炬的协同能量沉积。激光的功率密度要高得多，它将产生小孔，而等离子体炬产生的聚焦精细的等离子体射流将提供额外的能量沉积。通过对等离子体射流和激光诱导等离子体的主动调节来稳定小孔。闭环式激光深熔焊接工艺的成功开发将是这一领域的突破。申请SGER赠款将使PI能够证明协同能量沉积概念以及工艺的固有稳定性，从而为闭环系统奠定基础。由于缺乏实时反馈传感器，这样的闭环系统还没有被尝试过。这项技术将使激光焊接在更大范围的行业中经济上可行。美国工业需要这种先进技术来提高竞争力，以扭转许多大公司将工作外包出去的趋势。此外，美国激光工作商店(超过10,000家)将看到他们的服务能力大大提高，因为这种技术的可用性。在计算上，该项目使用了新的数值策略组合。这项工作是在一个跨学科的小组环境中进行的，通过课程和项目将研究与本科生和研究生结合起来。

This SGER grant aims at developing a pilot system to achieve synergistic and stable deep penetration welding by combining a fiber laser and a plasma jet. The success of this pilot system heavily relies on a real-time plasma sensor and the integration of the fiber laser and the plasma jet. To develop this real-time plasma sensor, a high speed photography system will be integrated with a high performance computing system for image processing at a frame rate up to 200,000 fps. This high speed photography system allows the PIs to observe the oscillation of keyhole and plasma ejection in order to validate and refine the design of the new plasma sensor array. The observation also allows the validation of rigorous mathematical modeling of the laser/plasma-jet process currently under development. The key technology resides in synergistic energy deposition of a laser beam with moderate power and a plasma torch with a special nozzle design. The laser, with its much higher power density, will create the keyhole while a finely focused plasma jet from the plasma torch will provide additional energy deposition. The keyhole will be stabilized through active regulation of the plasma jet and the laser-induced plasma. The successful development of closed-loop deep penetration laser welding processes will be a breakthrough in this area. The request SGER grant will allow the PIs to prove the synergistic energy deposition concept as well as the inherent stability of the process, thus, establishing the foundation for a closed-loop welding system. Such a closed-loop system has not been attempted because the lack of real-time feedback sensors.The technology will render laser welding economically viable for a much larger range of industries. The US industry is in need of this kind of advanced technology to boost competitiveness in order to turn back the tide of off-shoring jobs by many major corporations. Further, US laser job shops (over 10,000) will see their service capability significantly increased by the availability of such a technology. Computationally, the project uses novel combination of numerical strategies. The work is being performed in an interdisciplinary group environment that integrates research with undergraduate and graduate students through both courses and projects.