Damage identification of wind turbine blades based on acoustic emission

Abstract

Wind turbine blades are subjected to alternating fatigue load caused by wind and, as a result, are prone to damage. It is hard to investigate the damage mechanism of the blades due to their complex structure and large size. In this paper, damage to wind turbine blade composites is identified based on acoustic emission (AE). Samples of singlecomponent glass fibre/epoxy resin composite laminate [90°] and [45°] were prepared and put through a tensile process and the acoustic emission signals during this process were analysed using cluster methodology and wavelet packet transformation. The results show that there are four damage modes: matrix damage, fibre break, interface damage and delamination, with the characteristic frequency bands of 0-0.06 MHz, 0.06-0.12 MHz, 0.25-0.32 MHz and 0.37-0.45 MHz, respectively. The damage process of laminate [45°] is analysed using the damage evolution diagram. The tensile process can be divided into four stages: matrix damage and interface damage appear first, then the fibre starts to break, after which follows the stationary expansion stage, resulting in interlaminar damage until fracture.