MULTIAXIAL AND UNIAXIAL FATIGUE ANALYSIS OF A MOORING CHAINS FOR AN OFFSHORE FLOATING WIND TURBINE

This paper presents the fatigue study (uniaxial fatigue and multiaxial fatigue) of mooring chains for a floating wind turbine (FWT). The operating principle of a floating offshore wind turbine (FOWT) and general information on uniaxial and multiaxial fatigue are presented, together with a reminder of the standards governing fatigue in the offshore sector. Uniaxial fatigue damage and service life calculations are carried out for various loading conditions and sea states. The finite element method is carried out using ANSYS software in order to estimate the best mapping of stresses and strains on the structure of the mooring chain. Finally, a simulation was also carried out using usingMatlab software to calculate the damage and multiaxial fatigue life. Comparison of the two analyses shows that uniaxial fatigue analysis minimises long-term damage and that multiaxial fatigue should be preferred for estimating the durability of offshore structures under extreme loading.