A Comparative Study on the Fatigue Life of Mooring Lines under Combined Stresses
Palavras-chave:
mooring lines, fatigue analysis, out-of-plane bending, in-plane bending, combined tensionResumo
Mooring lines are essential for offshore floating platforms, but accurately assessing their integrity and
fatigue poses a challenge. Traditionally, fatigue calculations only considered tension loads, neglecting out-of-plane
bending (OPB) stresses caused by plastic strains during the proof loading process in chain links. This oversight
may lead to early failures. Bureau Veritas guidelines BV NI604 propose a fatigue analysis method that considers
combined stresses for fatigue crack initiation. This study presents a comparative analysis of mooring line fatigue
life, comparing traditional methods with BV NI604's approach. Two case studies are examined: one focuses on an
FPSO vessel with a turret mooring system, experiencing significant out-of-plane bending due to turret rotation,
while the other explores an FPSO vessel with a spread mooring system. The analysis highlights the importance of
considering combined stresses and bending effects to ensure the safety of offshore installations.
