Advanced fatigue assessment - the future of wind turbine towers

Abstract

One of the sustainable development goals of the Green Deal established by the European Union is the demand of affordable and clean energy. Among the renewable energies, the wind energy is already crucial in reaching the ambitious goals and will become even more important in the future. Since economic aspects will gain more importance, an efficient use of materials and resources is essential, especially those related to the fatigue design and service life prediction of wind turbine towers made of steel.This paper introduces an advanced fatigue assessment method, using the strain-life approach and the crack propagation method, named Two Stage Model. This model combines the two phenomenological aspects of crack initiation and propagation for a more reliable fatigue service life prognosis compared to commonly applied and simplified methods. By investigating both parts of the Two Stage Model separately, the paper shows the effect of selected input parameters on the service life for constant stress amplitudes. A Monte-Carlo Simulation is applied to validate the Two Stage Model as a vulnerable and reliable fatigue assessment concept.