This paper investigates the aeroelastic characteristics of wind turbine blades under rated condition, with a focus on analyzing the impact of strength degradation on the structural safety of the blades. The NREL 5 MW wind turbine blade is selected for the case study. The fluid-structure interaction (FSI) simulation is conducted under rated conditions within STAR-CCM+ and ABAQUS. The strength degradation is implemented by decreasing the strength of layup materials in the cap and leading edge regions. The tip-displacement and stress distribution of the blade with different strength degradations are compared for the analysis of the impact of local strength reduction on aeroelasticity. The results show that the aeroelastic responses of the blade are influenced by material strength and degradation position. The impact of local strength degradation at the blade root is more significant than that at the tip. In most cases, blades with decreased strength exhibit larger tip displacement and lower natural frequencies. Structural analysis indicates that the stress in the strength degraded areas is lower and the neighboring regions are bearing the load, which may cause the material to reach the yield limit earlier, affecting the safety of the blade. In addition, when local strength degradation occurs at the cap, it primarily affects the flap displacement of the blade, while the edgewise responses are more sensitive to the strength degradation at the leading edge.
Lai et al. (Mon,) studied this question.