On the Development of a Damage Detection System using Macro-fibre Composite Sensors

Macro-fibre composite (MFC) sensors, originally developed as actuators by NASA, have been investigated for three components of a damage detection system for composite structures; actuation, sensing and energy harvesting. MFC sensors are constructed from piezoelectric fibres embedded in an epoxy matrix and offer greater flexibility than traditional sensors for embedding due to their low profile and low weight. It is proposed that embedded MFCs could be used to act as damage detectors, whilst energy either transmitted ultrasonically or harvested ambiently could be used to power the system. To assess the applicability of the MFCs a scale A320 composite wing was manufactured. Ten MFC sensors were embedded within the wing structure. Through a series of investigations on the wing the use of MFCs as part of an acousto-ultrasonic (AU) and Acoustic Emission (AE) damage detection system were investigated. Utilising AE source location and an AU cross-correlation techniques damage induced by impact was identified. In a further experiment the capability of transmitting and harvesting energy with the same embedded MFC actuators was completed. By impedance matching it was possible to improve the transmitted power. Furthermore an analysis of the MFCs ability to capture ambient vibrations, associated with aircraft structures, was completed. The completed experimental work demonstrated that it would be possible to embed sensors, energise them through active or passive vibration, and detect damage