Application of ultrasonic technology in sheet joining: review article.

Ultrasonic joining plays an important role in low-damage and high-efficiency manufacturing of sheets, owing to its advantages such as concentrated energy, small heat-affected zone, and no need for filler materials. This paper provides a summary from three aspects: ultrasonic joining processes, ultrasonic non-destructive testing (NDT), and the application of data-driven methods. In terms of ultrasonic joining, the main forms of ultrasonic application in sheet joining are reviewed according to the differences in ultrasonic mechanisms, among which the ultrasonic vibration effect has become an important performance enhancement means in various hybrid joining processes. With regard to ultrasonic NDT, in-situ, non-contact, and intelligent approaches represent the current major development directions. Concerning data-driven methods, this paper summarizes the current status of their applications in process optimization and process monitoring, and points out that weak cross-scenario transferability and insufficient generalization performance of existing models remain key bottlenecks. Finally, this paper outlines future development directions, including multi-energy field hybridization, machine learning-assisted process control, and high-power equipment development.