Incidence of spectrum estimation methods on the fatigue life assessment of mooring lines for floating offshore wind turbines

The paper focuses on the fatigue life assessment of mooring lines for floating offshore wind turbines, deployed on intermediate water depths. The nonlinear hydrodynamic model in the time-domain is preliminarily discussed. Subsequently, several spectrum estimation methods are outlined and embodied to carefully assess the low and high-frequency components of the stress process in the mooring lines and estimate the cumulative fatigue damage by the combined spectrum approach. The spectral reconstruction methods are applied to a reference case study, focusing on three different loading conditions. Current results are discussed and some suggestions are also provided to carefully assess the fatigue life of mooring lines for floating offshore wind turbines.