Alternating strain response of fibre Bragg grating sensors embedded into carbon fibre composites for wind blade health monitoring

In this paper, we propose the use of a series of fibre Bragg grating (FBG) sensors encapsulated in dedicated packaging made of carbon fibre reinforced polymers (CFRP) for monitoring the structural health of wind turbine blades. The manufactured CFRP packages are experimentally tested in a real-field fatigue test carried out on a 56.85 m-long composite wind blade over 16 days, in which alternating loads (i.e. tensile and compressive strain) are applied to the entire wind blade. Experimental results indicate the CFRP-packaged FBG sensors provide dynamic strain measurements with high precision and with no degradation over time, as shown to happen with conventional strain gauges.