Fatigue of GFRP in Wind Turbine Rotor Blades

Abstract

In the 20-years' life time of wind turbines, the rotor blades achieve more than 10 exponent 8 load cycles. However, for a reliable life time prediction high-cycle fatigue data were missed up to now. Within a CEC programme, therefore relevant investigations on both GI-Ep specimens and spar beams including the load attachment to the hub were carried out. The experiments enclosed sinusoidal one-step tests and the wind energy-specific load sequence WISPER. For the GI-Ep specimens a life time prediction was performed with the linear Miner rule on the basis of a constant amplitude life diagram designed by the fatigue data. Concerning the spar beams it was shown that they safely can withstand maximum strains of more than -0.6 per cent. Frequency response and damping measurements were carried out at certain stages during service life but could not discover an impending failure.