INVERSE CALCULATION OF EQUIVALENT ELASTIC CONSTANTS OF FIBER REINFORCED COMPOSITE WIND GENERATOR BLADES FROM DISPLACEMENT AND NATURAL FREQUENCY MEASUREMENTS

An inverse calculation method is proposed in this study to determine the equivalent elastic constants of a wind generator blade. In this method, a deviation function is constructed using elastic displacements and natural frequencies of the blade. The function is thereafter optimized to determine the equivalent elastic constants. The static displacements and shock responses of the wind turbine blade are determined by the digital image correlation method and the deviation function is optimized by the genetic algorithm with the flexible allowance technique. Inversely calculated equivalent orthotropic elastic constants are verified by more static experiments on the blade. The elastic constants are also used to calculate the mode shapes of a three-blade rotor, which agrees with the mode shapes of a single blade.