Abstract: To solve damage identification problem of wind turbine blade structure in different cases, a stepwise method based on unit mode strain energy change rate and BP neural network is used. Change of mode strain energy per unit is compared to judge damage preliminarily. A mapping model is built for reflecting the relationship between the characteristic parameter and damage state to indentify the location and degree of damage, and the mode strain energy change rate is treated as characteristic parameter characterized structure damage. The results show that unit mode strain energy can judge possible damage unit effectively, and BP neural network can indentify structural damage location and degree more accurately. The method has good recognition effect for many damage cases.

Key words: wind turbine blade structure, damage identification, mode strain energy, BP neural network