Acoustic emission source location in complex aircraft structures using three closely spaced sensors

The use of three piezoelectric sensors in a small array has previously been investigated to assess its ability to locate Acoustic Emission (AE) sources in simple aluminium and composite structures. It has been theorised that this approach could be used within wireless systems to monitor AE in aircraft, as the close spacing of the sensors removes the need for power-intensive time synchronisation between nodes and reduces excessive cabling. There are, however, two major limitations to this, primarily that the localisation techniques used are only viable within simple structures and additionally that the high computational requirements of the continuous wavelet transform which the technique utilises is infeasible for a low power system. This paper presents modifications to this approach, including the novel second differential method for single sensor modal analysis, which enables the technique to locate AE events within complex structures. A mapping technique is also presented, which accounts for complexity and varying wave velocity in composite structures. Testing is presented which uses artificial sources on a range of structures, from simple plates to an Airbus A350 aircraft wing, with a high level of accuracy and repeatability shown.