Numerical analysis of fatigue strength for ultra-large ships considering springing

Abstract

Due to the low stiffness of ultra-large ships, the effect of springing becomes more obvious. The traditional quasi-static spectral method (QSM) ignores the coupling effect of hydrodynamic load and hull elastic characteristics, so it is unable to solve the problem of fatigue strength considering springing. To solve the problem and investigate the impact of springing response on fatigue, the stress mode superposition spectral method (SSM) suitable for ultra-large ships is proposed. The numerical analysis is performed on a real ship as an example. The results show that: Fatigue stress response generates new peaks at the high-frequency regions when considering the effect of springing, and fatigue damage is greatly increased. The degree of influence of springing response on fatigue strength is related to wave incident angles and sea conditions. This method has reference significance for the evaluation of fatigue strength of ultra-large ships considering springing effects.