Evaluation of mooring line degradation in floating offshore wind turbines: a comprehensive analysis of corrosion and fatigue under environmental impacts

As the demand for renewable energy grows, floating offshore wind turbines have become crucial, especially in deep water areas where traditional structures are impractical. These turbines need station keeping systems, which often consist in catenary mooring lines, making their durability vital against extreme weather conditions. While direct monitoring of these lines would be preferable, it is often unpractical due to high costs and maintenance. This research presents a new method to evaluate the degradation of mooring lines. The study investigates fatigue and corrosion behavior along the mooring lines by simulating environmental impacts, considering varied forces and weather patterns. Considering seawater’s oxygen and temperature, a distinct corrosion model is merged with fatigue performance predictions based on DNV standards. Mooring line loading conditions derived from environmental factors are then incorporated into a finite element model, assessing various load cases and corrosion’s role in line degradation. This comprehensive model examines the combined effects of corrosion (in particular, pitting corrosion) and fatigue, including hydrostatic pressure and out-of-plane bending on the performance of the mooring line chain in the offshore environment. The methodology’s validation relies on previous research and mooring line operational data.