Aeroelastic study of large offshore wind turbines under blade failure and detachment events

Blade breakage incidents have become increasingly frequent in the wind energy industry. When a blade fractures and detaches during operation, the inertia and aerodynamic load distribution become highly unbalanced, leading to severe transient loads on the remaining structure. The rotating blades generate significant unbalanced centrifugal forces, while gravity-induced torques vary with rotor azimuth, resulting in complex dynamic responses. Using the IEA 15 MW and 22 MW reference offshore wind turbines, this study investigates post-fracture load mechanisms through aeroelastic simulations under turbulent wind conditions with an active emergency shutdown control strategy. Results indicate that unbalanced centrifugal forces are the dominant contributor to the large bending moments in the tower and monopile. Peak bending loads strongly depend on the rotor azimuth at the instant of blade detachment; they reach up to two times those of the intact turbine under turbulent conditions and occur near 210°. In addition, the main shaft bending moment also increases significantly after blade detachment. These findings highlight the necessity of verifying structural integrity under blade fracture and detachment conditions.