Lifetime Prediction for GFRP Fabrics Comparing the WISPERX Standard and a Measured Spectrum

More than 10 years ago, the WISPER/WISPERX standard was introduced specifically for wind energy application by an IEA study group. It represents a world-wide available, non-changeable load sequence composed by measurements on various Horizontal Axis Wind Turbines (HAWT) of sizes between 10 kW and 3 MW. It was intended to use it for purpose like e.g. material comparison and methodology of lifetime prediction. Today, the development of wind turbines is focussed more on large machines, beyond about 0.3 MW. Therefore, the question may be raised whether the WISPER-standard as a mixture of fatigue loads of all possible rotor sizes reflects the damage on rotor blades of modern machines in the right way and/or whether it could be used even for HAWT certification.