Abstract: The Rules for the Classification of Trimarans by Lloyd's Register of Shipping are mainly for steel trimarans and are not applicable to aluminum-alloy trimarans. The fatigue life of a 120m aluminum-alloy trimaran is calculated by using the direct calculation method (spectral analysis method) based on the Miner linear cumulative damage theory. At the same time, the fatigue assessment results are corrected by the rain flow correction with consideration of the difference between treating the alternating stress process as a narrow band and the actual sea state. The results show that fatigue damage is easy to occur at the bridge of the aluminum-alloy trimaran, and hot spots have the different contributions to the fatigue damage under the different wave angle. The results of the fatigue life calculation are conservative if the alternating stress process is regarded as a narrow-band model. The conclusions can provide reference for the fatigue assessment of the aluminum-alloy trimaran.

Key words: aluminum-alloy trimaran, spectral analysis method, fatigue life, rain flow correction

摘要： 劳氏三体船规范主要针对钢制三体船,对铝合金三体船并不适用。该文以某120 m铝合金三体船为例,基于Miner线性累积损伤理论,运用直接计算法——谱分析法进行三体船疲劳寿命计算;同时考虑到将交变应力过程当成窄带处理与实际海况不符,对疲劳评估结果进行雨流修正。结果表明：铝合金三体船连接桥部位容易产生疲劳破坏,热点在不同浪向角下疲劳损伤贡献度不同;若将交变应力过程视为窄带模型,三体船疲劳计算结果偏保守。所得结论对铝合金三体船疲劳评估具有参考意义。

关键词: 铝合金三体船, 谱分析法, 疲劳寿命, 雨流修正