A critical review on the structural health monitoring methods of the composite wind turbine blades
With increasing turbine size, monitoring of blades becomes increasingly important, in order to prevent catastrophic damages and unnecessary maintenance, minimize the downtime and labor cost and improving the safety issues and reliability. The present work provides a review and classification of various structural health monitoring (SHM) methods as strain measurement utilizing optical fiber sensors and Fiber Bragg Gratings (FBG's), active/passive acoustic emission method, vibration-based method, thermal imaging method and ultrasonic methods, based on the recent investigations and promising novel techniques. Since accuracy, comprehensiveness and cost-effectiveness are the fundamental parameters in selecting the SHM method, a systematically summarized investigation encompassing methods capabilities/limitations and sensors types, is needed. Furthermore, the damages which are included in the present work are fiber breakage, matrix cracking, delamination, fiber debonding, crack opening at leading/trailing edge and ice accretion. Taking into account the types of the sensors relevant to different SHM methods, the advantages/capabilities and disadvantages/limitations of represented methods are nominated and analyzed.