Influence of cracks on the buckling of wind turbine towers

The collapse of a wind turbine can be caused by the buckling of the tower when it is subjected to a critical load. This load is related, for instance, to a strong storm or a blade impact on the tower. Buckling occurs when the elastic limit is reached in part of the tower. Plasticity leads to bending with large rotations and large displacements. Structures are designed to avoid this phenomenon. However, a wind turbine is subjected during its entire service life to operation loads which cause fatigue of the structure. This results in the initiation of cracks and their propagation in the tower. These cracks can reduce the tower strength and it is, thus, interesting to study how the presence of such damage can affect the resistance of a wind turbine tower to the buckling. The influence of different parameters, such as position and length of the crack, is analyzed. Finally, the critical buckling load is related to wind site condition by considering an aero-elastic modeling of the wind turbine.