High Accuracy Non-Contact Monitoring for Hole-Edge Crack of Aircraft Attachment Lug Based on Guided Wave Network

Abstract

The attachment structure is the key component to ensure the structural integrity and bearing capacity in aircraft structure, and its service environment is often complex and harsh. As the main attachment structure between fuselage and wing, the aircraft attachment lug is much possible to initiates hole-edge crack at any direction and propagates, which leads to a decrease in structural integrity and then fracture failure. Owing to the advantages of non-contact monitoring, the hole-edge crack monitoring based on guided wave-structural health monitoring (GW-SHM) method has always been a topic of concern in recent years. However, research on aircraft attachment lugs still needs to be further developed. Due to the existence of large bolt hole and complex propagation characteristics of GW in aircraft attachment lug, it is difficult to accurately monitor hole-edge crack damage, especially small cracks. Aiming at this problem, a high accuracy monitoring method based on guided wave network is proposed in this paper. The damage features in GW network are quantified accurately by damage index (DI) method, and a reliable alarm mechanism is constructed. The crack localization imaging method is optimized for the bolt hole form to enhance the monitoring accuracy. The proposed method is verified by a monitoring experiment of small hole-edge crack in aircraft attachment lug. The results demonstrate that this method can achieve correct damage alarm and accurate damage location, which provides a research idea for the accurate monitoring of hole-edge crack damage.