Structural–functional components via ultrasonic additive manufacturing: a review of fabrication and functionality

With the increasing demand for structural health monitoring and high-performance materials in the aerospace industry, traditional manufacturing processes are no longer capable of meeting the requirements of complex structures and multifunctional materials. Ultrasonic Additive Manufacturing (UAM), as an emerging additive manufacturing technology, combines the advantages of low-temperature processing and efficient material handling to provide a novel solution for embedding sensors and manufacturing functional structural parts. This paper comprehensively investigates the impact of multiple factors, including the type of metal matrix, coating treatment, optical fiber channel, and process parameters, on the interfacial bonding strength between optical fibers and metal matrices when different types of sensors, such as multimode fibers, single—mode fibers, and special fibers, are embedded in the metal matrix via UAM. Survey results indicate that aluminum is currently the most commonly used matrix material due to its softness. Moreover, appropriate coatings, fiber channels, as well as optimized process parameters can significantly enhance embedding effects while reducing fiber damage during embedding. Additionally, sensing characteristics of UAM-embedded fiber-optic sensors are reviewed, including temperature sensing properties, strain sensing properties, bending sensing properties and torsion sensing properties along with their applications in complex structures. Furthermore, this paper also describes technical methods for embedding other sensors (e.g., PVDF fibers electronic components) into a metal matrix. By utilizing UAM, it is also feasible to fabricate complex structural components with multiple functions which demonstrates vast potential for application especially within the aerospace field. Finally, the development and application prospects of UAM are envisioned.