Bi-axial fatigue test method for ultra-large wind turbine blade based on Tug Fatigue Testing system

To enable the large-scale wind turbine blades to endure loads that are closer to actual operating conditions during fatigue testing and to shorten the testing period, a bi-axial fatigue testing method for blades based on Tug Fatigue Testing method is introduced. Firstly, a bi-axial dynamic model for the blade testing system is established, which examines the coupling relationship between the exciting forces and the blade responses in flap-wise and edge-wise directions. Based on the analysis of the coupling relationship, the blade coupling signal is analyzed to obtain the resonance frequency of each main vibration direction of the blade and the best excitation moment of the exciting force, and the corresponding bi-axial control strategy is designed. The simulation results of a certain type of 90-meter blade have verified the applicability and accuracy of the bi-axial dynamic model. Additionally, the blade actual test was conducted based on the control strategy, successfully verifying the validity of the control strategy of Tug Fatigue Testing method. This paper provides a practical reference for the bi-axial fatigue testing of wind turbine blades, further advancing the development of wind turbine blade testing technology.