Abstract: the composite ply with the internal structure of the complex configuration for a new 2MW wind turbine blade is designed initially based on such generation design method. The finite element parametric model for the blade is established in detail. Based on the modified blade element momentum (BEM) theory, a new fluid-structure interaction method that is suitable for the design and optimization is presented. The mathematical optimal model is development. In the optimization model, the objective is the minimum blade mass and the design variables are lamina thickness, beam thickness and so on. The optimal method for the composite blade is combined PSO algorithm with the finite element method. The results are showed that, compared to the initial blade, the mass of the optimized blades is reduced largely, and especially for the results of scheme two (the location of blade beam is seen as one of the variables) is better. The study has important guiding significance for the structural optimization design of wind turbine blades. Moreover, this will make the integrated design of the wind turbine airfoils, blades and structure came true.

Key words: wind turbine blade;ply design;finite element method;blade element momentum theory;PSO algorithm