Health monitoring of aerospace structures with acoustic emission and acousto-ultrasonics

In today's economy, structures must remain in operation for much longer per iods of time than originaly anticipated. Thr ageing effects on these struct ures are becoming significant and must be accounted for in the decisions ma de regarding usage, maintenance, and retirement of these structures. The development of non-destructive testing techniques to monitor the condit ion of these structures is very active and these developments are focused o n extending the remaining lives and/or reducing the costs of maintenance of existing structures. A fast, accurate anti cost-effective Method of struct ural monitoring that has shown to be very reliable, and can inspect both 'l ocally' and 'globally', is acoustic emission (AE) and acousto-ultrasonics ( AU). AE/AU technology can detect structural defects long before possible ca tastrophic failures. Complementing other NDT testing methods, AE/AU has pro ven To be a reliable and 'sound' technology for structural health monitorin g within a predictive maintenance programme. This is possible because disco ntinuities will produce detectable emissions, long before structural integr ity is compromised and structural failure occurs. Acoustic emission and acousto-ultrsonics technology can be applied to many of today's ageing structure problems, ranging from structural health monito ring in the aerospace industry to locating discontinuities in hybrid compos ite structures for active flaws. This paper will examine this technology an d discuss several applications and monitoring scenarios.