Application of a Fibre-Optic Acoustic Emission Sensor to the Fatigue Testing of Wind Turbine Blades


Journal of Smart Materials and Structures (submitted)

C. Doyle, C. Tuck, R. Chen, G. F. Fernando, G. Zheng, T. Liu, P Joosse, D R V van Delft, A G Dutton, M Blanch, P Vionis, V. Kolovos, A Anastassopoulos, D Kouroussis, T Kossivas, J. ter Laak, T. P. Philippidis, Y. G. Kolaxis, A. Proust


The detection of acoustic emission from composites can help to diagnose the condition of a structure made from such materials.  Conventionally, monitoring is performed by surface-mounted piezoelectric transducers.  These transducers are relatively bulky and can be susceptible to electrical interference, drawbacks which could be overcome by using fibre-optic sensors if they had adequate sensitivity.

This paper presents a new type of acoustic emission sensor, based on a fused tapered 2 x 2 coupler.  Sensors were mounted on the surface of a glass-epoxy panel, excited with simulated AE signals and their output was compared to that of a commercial piezoelectric transducer.  The amplitude of the fibre-optic sensor response was only 20 dB less and a signal-to-noise ratio of 45 dB was achieved.  Devices have been integrated into a commercial AE instrumentation system and used for acoustic emission monitoring of a glass-polyester composite coupon during a tensile test. Data generated by a fibre-optic sensor during a fatigue test on a small wind turbine blade, made of the same material, are also presented.