Dynamics and Fatigue Damage of Wind Turbine Rotors during Steady Operation

A number of sub-models for use in the evaluation of the load-carrying capacity of a wind turbine rotor with respect to short-term strength and material fatigue are presented. The models constitute the theoretical basis of a computer code ROTORDYN which, in conjunction with an initial finite-element analysis and eigenvalue extraction, performs a dynamic analysis of a wind turbine rotor for lifetime prediction. The models comprise a structural model which is essentially linear and solves for periodic and stochastic loading in the frequency domain. The model includes the centrifugal stiffening of the blades and a linearization of the aero-elastic effects as well as power regulation by pitch control* The aerodynamic model is based on blade element theory. (continued on next page) July 1984 Riso National Laboratory, DK-4000 Roskilde, Denmark

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