Superelement-based acceleration of finite-element simulations of wind turbine rotors

Large numbers of wind turbine rotor finite-element simulations are required for blade bearing raceway and ring fatigue calculations. Finite-element rotor models come along with a complex nonlinear model behaviour and a high number of degrees of freedom due to the necessity of considering the blade bearing's surrounding structures. For that reason, accelerating such simulations is of particular interest for the iterative design process. This study focuses on different superelement configurations for the rotor model of the IWT 7.5-164 reference turbine. The blade bearing's resulting contact forces and contact angles are analysed for 18 load steps throughout an exemplary rotor rotation and the respective model results are compared to each other. The results show that implementing superelements in the rotor model significantly increases the computational efficiency with an acceptable loss of accuracy in terms of the blade bearing's internal loads. Furthermore, it is shown that such models outperform the acceleration and especially accuracy achieved by the usage of a one-third rotor model.