Research on multi-load distributed strain monitoring for wind turbine blades based on weak fiber Bragg grating arrays

Abstract Wind turbine blades are frequently subjected to harsh environmental conditions, such as high altitudes and salt-laden atmospheres, leading to structural damage including cracks and delamination. To enable timely and effective monitoring of blade health and prevent progressive degradation, this study proposes a distributed strain detection method based on weak fiber Bragg grating arrays. This method effectively receives reflected echoes from multiple weak grating points by integrating optical frequency domain reflectometry, thereby enhancing strain measurement sensitivity. After calibration, the system exhibits a strain sensitivity of 0.821 41 μϵ pm −1 and a linear fitting coefficient of 0.994 86. Additionally, a temperature compensation decoupling strategy is introduced to improve strain measurement accuracy. A multi-load simulation experimental platform was developed to investigate blade strain characteristics under three typical operating conditions. The results confirm the method’s capability for reliable distributed strain sensing across various loading scenarios, identify the blade root and mid-span regions as high-risk zones, and reveal 0.4 Hz and 4.5 Hz as key diagnostic frequencies for dynamic blade behavior. This work presents a robust, long-range strain monitoring method with high reliability and strong interference resistance, supporting early damage detection and optimized maintenance of wind turbine blades.