Abstract: This paper studies the calculation of bending and torsional stiffness of wind turbine composite blades, as well as the numerical calculation method of shear stress on the hollow thin-walled section when the blade is subjected to transverse shear force. Modern wind turbine blades are slender and twisted, with thin-walled airfoil sections and complex internal topological configurations, and the materials are anisotropic. When applying various beam models for mechanical analysis such as blade aeroelastic calculation and strength check, the stiffness coefficient of the blade section and the calculation results of the section shear stress distribution are required parameters. Based on the composite thin-walled structure lamination theory and weighted average method, combined with the Bredt-Batho shear theory, a numerical analysis algorithm for the equivalent elastic constant and section stiffness coefficient of the composite laminate was established, taking into account the shear web effect of the composite blade. and warping effects; based on the plate and shell theory of elastic mechanics and considering the influence of transverse shear and section warpage on section deformation, a numerical calculation method for shear flow caused by transverse shear was established; a Matlab program for related algorithms was developed. By analyzing the main stiffness coefficient and shear flow distribution of a 10 MW wind turbine blade and comparing the literature results, the correctness of the model and the effectiveness of the algorithm are verified.

Key words: wind turbine blade, composite, equivalent elastic constant, classical lamination theory (CLT), shear flow