Assessment of the impact of typhoons on crack propagation and fatigue life of OWT tower

Accurately predicting the effects of extreme weather on offshore wind turbines (OWT) is crucial for ensuring their safety and normal operation. This study combines fluid-structure interaction (FSI) and linear elastic fracture mechanics (LEFM) to simulate the crack propagation behavior of a 2.1 MW OWT tower in the offshore environment. First, ANSYS finite element software is used to simulate the OWT under normal operating conditions to determine the hot spot stress locations and introduce initial cracks at these locations. Then, the crack propagation process of the tower is simulated using FRANC3D software, and the fatigue crack propagation life (FCPL) is assessed using the Forman-Newman-de Koning (FNK) model. The study concludes that the middle and upper parts of the OWT tower are the most dangerous locations, influenced by aerodynamic and inertial loads, with initial cracks tending to extend linearly to both sides after penetrating the tower wall thickness. The occurrence of typhoons significantly reduces the FCPL and critical crack length of the tower, with the FCPL numerically decreasing from 4.75 years to 2.46 years, and the critical crack length decreasing from 1079.67 mm to 608.49 mm. The results of this study can provide a reference for maintenance and reinforcement work by technical maintenance personnel.