An Analytical Model to Extract Wind Turbine Blade Structural Properties for Optimization and Up-scaling Studies

A wind turbine blade has a complex shape and consists of different elements with dissimilar material properties. To do any aeroelastic simulation, the structural properties of the blade such as stiffnesses and mass per unit length should be known in advance, and extracting these properties is a difficult task. This paper presents an analytical model to extract these structural properties in a simple way. It starts with calculating an equivalent material property of the cross section using weighting method. Then the centroid of each section is obtained. Next the second moment of inertia of each element relevant to its local coordinates system is calculated and transferred to the centroid of the section using parallel axis theorem. A coordinate transformation is employed to rotate these second moment of inertias around any arbitrary axis. Finally, flapwise and edgewise stiffnesses are found by multiplying the equivalent modulus of elasticity to the second area moment of inertia in each section. Mass per unit length is calculated by multiplying the equivalent density to the real area of each section. The method is verified with the structural properties of a commercial 660 kW wind turbine blade. Despite the simplicity of the method the results show a good agreement.