An Identification Method of Appearances and Expansion of Fatigue Crack in the Wind Turbine Blade Based on Fractal Feature

In this work an efficient and simplified method for crack identification in wind turbine blade has been developed based on fractal dimension. Firstly, the algorithm is studied on the calculation of the correlation dimension of acoustic emission signals, and an analysis of these equations makes it possible to identify cracks. Then it turns out that the complexity could vary with different crack expansion conditions, i.e. reduction and augmentation of the correlation dimension due to the occurrence of a crack by the fatigue experiment. Finally, the proposed detection methodology is compared to wavelet analysis. It is testified that the method exploits both the typical steady expansion of the crack and the appearance phenomenon due to the presence of crack.