These slides were presented at the NAFEMS World Congress 2025, held in Salzburg, Austria from May 19–22, 2025.

Abstract

Floating offshore wind platforms are subjected to complex cyclic loading caused by waves, wind, and currents, creating significant fatigue risks in critical welded joints. These joints are primary stress concentrators and require precise evaluation to ensure structural integrity and compliance with offshore standards such as DNV RP-C203. This study focuses on the fatigue performance of these structures, providing a detailed approach to fatigue life assessment and structural optimization under harsh marine conditions. The analysis begins with environmental load modeling, incorporating parameters such as wave heights, wind speeds, and current forces. These factors are used to simulate the six-degree-of-freedom motion of the platform, including surge, sway, heave, roll, pitch, and yaw, which induce complex multi-axial stress states. Welded joints, representing high-risk failure points, are analyzed using S-N curves and hot-spot stress methodologies to evaluate cumulative fatigue damage over time. Managing the extensive datasets generated by offshore loading scenarios is a critical challenge. This study employs advanced filtering techniques and rainflow cycle counting to identify significant stress cycles while minimizing computational effort. These methods enable the isolation of high-impact stress ranges, focusing analytical resources on areas where fatigue damage is most likely to occur. Based on the results, structural refinements are proposed, including adjustments to weld throat thickness, material properties, and joint configurations. These changes aim to improve fatigue resistance and ensure a service life of 25 years under demanding operational conditions. The findings demonstrate that these refinements not only meet DNV RP-C203 compliance requirements but also extend the lifespan of critical components by addressing localized stress concentrations. This paper provides a robust methodology for fatigue analysis and structural optimization, offering practical insights for improving the reliability and safety of floating offshore wind platforms. The approach highlights the importance of data-driven engineering decisions in the development of durable and efficient renewable energy systems.