Spinning finite element analysis of longitudinally stiffened horizontal axis wind turbine blade for fatigue life enhancement. (November 2020) - Sajeer, Mohamed
Highlights: The spinning finite element analysis of stiffened wind turbine blade is the theme of this work. The impact of longitudinal stiffening is demonstrated using Campbell diagram. The stress time histories at different locations of the blade are investigated for uncontrolled and controlled cases. The fatigue life of the blade is estimated for uncontrolled and controlled cases. Sensitivity analysis is carried out with different tendon diameter. Abstract: In this study, a proof-of-concept is presented for extending the fatigue life of modern multi-megawatt wind turbine blades. For this purpose, spinning finite element model of the blade is investigated which has longitudinal stiffener (i.e. a tendon along its length) made of shape memory alloy. The material behaviour of the tendon is characterized by Liang and Rogers constitutive model in combination with thermodynamic principles. Modal analysis of the stiffened blade shows significant improvement of bending stiffness. The response of the blade with and without the stiffener are simulated using aerodynamic loads, which are evaluated following modified blade element momentum theory from the wind field generated by TurbSim. The impact of the proposed longitudinal stiffener on the stress profile and fatigue life of the blade are presented to show its performance. A sensitivity analysis on the reduction of peak stress and fatigue life for different diameters of the tendon are also presented.