Non-destructive evaluation (NDE) of aerospace composites: structural health monitoring of aerospace structures using guided wave ultrasonics

Monitoring safety-critical structures over their lifetime in order to improve reliability and availability and reduce life-cycle costs is of vital importance in many technical fields. Aerospace, with zero catastrophic failure tolerance, is the leader in the development of structural health monitoring (SHM) systems and considering the constantly increasing use of composite materials in aerospace applications, the development of SHM systems for aerospace composite materials and structures is of particular interest. This chapter outlines the present progress of health monitoring of aerospace composite structures by compiling the technologies used and summarising significant contributions made. First the three major transducer systems used are briefly reviewed. This is followed by a detailed discussion of the current status in four main areas of guided waves ultrasonic SHM systems development, namely transducer integration, simulation techniques, transducer network optimisation and signal processing. The results show that SHM will be one of the key technologies to ensure the structural integrity of ageing and future composite aircraft structures. At the same time it is recognised that a step-by-step implementation strategy is required to ensure direct technological and economical benefits, in which SHM systems with increasing complexities are taking over more and more responsibility