Abstract Summary
The exploration of the wind energy available offshore is of vital importance to overcome the energy dependence on fossil fuels and, depending on the deepness of different locations, this task may only be feasible if based on floating solutions. For onshore wind turbines, the fatigue damage experienced by the structure towers is significantly impacted by the wind conditions and the implemented control algorithms. In the case of floating offshore wind turbines (FOWT), the platform pitch and roll motions, induced by both wind and waves action, introduce additional sources of time varying stresses through two distinct mechanisms: by inducing low frequency wind action as perceived by the wind turbine and through the time varying rotor mass eccentricity. In order to properly extrapolate the fatigue damage, these effects must be taken into consideration. In this work, we have characterized and correlated the fatigue damage with different environmental conditions and measurable variables (e.g. accelerations) and discuss different methodologies to extrapolate the results to non-monitoring periods based on these findings.
