Towards ultra-fast and high strength structural repair of damaged thermoplastic composites: Ultrasonic welding

Owing to its high weld strength, rapid processing cycles and absence of foreign materials at the weldline, ultrasonic welding is considered as a promising technique for joining thermoplastic composites, as an alternative to traditional mechanical fastening and adhesive bonding. More importantly, this technique provides a potential possibility for repairing damaged composite structures with an extremely short duration. This paper presents a preliminary study on the feasibility of repairing an open-hole thermoplastic composite structure by using an external patch ultrasonically welded with different time durations. Both tensile and flexural behaviors of the repaired composite specimens were investigated. The damage processes of different specimens were synchronously characterized by using acoustic emission and digital image correlation techniques. Both the experimental and numerical results demonstrated a significant improvement in the mechanical performance of the weld-repaired specimens compared to the unrepaired ones. Additionally, the weld-repair patch effectively reduced the stress concentration in the periphery of the damaged area.