Structural Analysis of a Large Composite Wind Turbine Blade under Extreme Loading

This paper describes structural analysis of a large composite wind turbine blade under extreme loading. These extreme loading can cause damage and significant drop in the load-carrying ability of large composite wind turbine blades. Therefore, it is vital to investigate the structural strength of the blades for their safe operation during its life time. In this study first, a three-dimensional (3D) surface model of the blade is generated using NuMAD (Numerical Manufacturing and Design), which greatly simplifies the 3D model generation of a wind turbine blade, and effectively handles all information of blade airfoils, material properties and their geometrical configuration. The blade model is then evaluated for its ability to withstand the extreme loading conditions as specified in the relevant standards using finite element analysis (FEA) software ANSYS. Results show that the stresses and deformation in all parts except shear webs are within the design limits specified by standards. The higher stress level in shear web can be minimized by increasing the number of number of biaxial plies. Further, the structural weight of the blade is comparable to other blades of similar rated powers. Furthermore, optimizing the blade geometry and airfoil as well as ply layup especially in spar caps, and changing position of shear webs can have a profound effect on the overall performance and structural integrity of the blade.