Design of bend-twist coupled rectangular composite beams based on extension-twist multicoupled laminates

Wind turbine blades are easily damaged and fractured and power output is unstable under strong wind conditions, which are urgent problems to be solved. In this paper, the box structure of wind turbine blade is designed based on the extension-twist multicoupled laminates, which has the self-adaptive characteristics of bend-twist coupled deformation. The stiffness equation of the box structure is obtained by decoupling the deformation caused by the bending moment and torsion moment of the box structure, and the accuracy deviation of the torsional coupled stiffness is solved. The AOC 15/50 wind turbine blade is taken as an example, the paving optimization design is realized for the 80-ply hygrothermal stable extension-twist multicoupled laminates and their bend-twist coupled box structures. The results show that compared with the single-coupled laminates, the multicoupled laminates can not only increase the extension-twist coupling of the laminate (reaching more than 25%), but also greatly increase the bend-twist coupling of the box structure (reaching more than 40%). Finally, the robustness analysis is realized for the extension-twist coupling of laminates and the bend-twist coupling of blade, and the hygrothermal effect and coupling of the blade box structure are verified by numerical simulation.