Research on structural optimization methods for ultra-long flexible blades considering the multi-scale characteristics of composite materials

With the trend toward larger wind turbines, the increasing length of blades affects both power generation and safety. This study employs the MCT multi-scale failure criterion to investigate the multi-scale characteristics of woven composite materials. The performance parameters are predicted using a meso-scale model, and the results are applied to the structural analysis and optimization of blades. The results show that the material properties predicted by the multiscale method exhibit less than 10% error compared with experimental data. The optimized structure demonstrates significant improvement in axial stiffness with less than 3% mass variation. Reducing the layup mass at the blade tip while increasing mass in the mid-section effectively enhances structural performance. These findings provide valuable guidance for the structural design of ultra-long flexible blades in large wind turbines.