This article has provided a mere snapshot of some of the current approaches to the use of AE in SHM applications, in particular as applied to aircraft structures. The examples chosen have highlighted some of the particular problems associated with the AE technique and moreover have illustrated the solutions being developed. A simple case study has been used to illustrate the importance of integrating novel signal processing approaches with conventional AE analysis. The investigation demonstrated the ability of the AE technique to identify fatigue fractures in a landing gear component. Eleven groups of signals were identified based on AE source location. The feature data of the signals were extracted and a PCA analysis was performed, the result of which separated the group associated with final rupture from the groups of high amplitude and another group possibly related to pin noise. An MPI investigation showed that all groups that could not be separated from the final rupture and fracture source were indeed from fractures. KPDF was also demonstrated as a useful technique to aid visualization of damage locations. During the past 20 years, AE has come of age, with modal (waveform) analysis replacing the old approach based on waveform parameters. The emphasis on developing an in-depth understanding of the factors affecting the signal fromits generating source, through its propagation and on to the effect of the sensor and system, has proved to be hugely beneficial. The recent advances in microprocessors, in particular speed and storage capacity, have enabled a new generation of signal processing strategies and these techniques are able to make full use of the extensive information available in AE signals to provide extremely powerful data analysis strategies. It is evident that there are significant technical challenges associated with the use ofAE; however, it is also strikingly clear that the technical difficulties are being overcome by researchers using a modern approach to the subject. This leads to the conclusion that AE is an extremely powerful technique with enormous potential for addressing a fundamental concern of the aerospace industry, which is the ability to provide robust SHM solutions, both during testing of components and also in flight. As the next generation of aircraft will demand increased weight saving and thus will involve taking the designs to lower factors of safety, one of the keys to survival for aircraft manufacturers will be to ensure increased performance with confidence, to reduce cost of ownership, and to maintain safety standards.
Acoustic emission for monitoring aircraft structures
Überwachung von Flugzeugstrukturen mittels Analyse der Schallabstrahlung
2009
8 Seiten, 7 Bilder, 21 Quellen
Article (Journal)
English
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