西非海域FPSO多点系泊系统的疲劳寿命分析

文章首先采用三维频域理论分析西非海域FPSO的水动力性能,得到船体各自由度的运动响应,慢漂载荷,附加质量和势流阻尼等;随后,利用分块法将波浪散点图离散为若干个海况,基于准动态方法对多点系泊系统进行分析,得到各海况下船体的漂移和各系泊缆的张力;最后,结合前两步的计算结果,采用T-N曲线,雨流计数和Miner线性累计损伤理论对系泊缆的疲劳寿命进行预报。研究结果表明,各系泊缆的疲劳寿命沿长度方向的分布趋势基本一致,锚链顶端和触底部分的疲劳寿命较短。此外,西非海域的涌浪对系泊缆的疲劳损伤较大,系泊设计时应予以重点关注。

Fatigue life analysis of FPSO multi-point mooring system in west africa sea

Firstly, the hydrodynamic performance of Floating Production Storage and Offloading (FPSO) in West Africa Sea is analyzed by the three dimensional frequency domain theory, in order to get the motion response, slow drift loading, added mass and potential damping for each degree of freedom. Secondly, wave scatter diagram is discretized into several sea states by block method. It analyzes the multi-point mooring system based on the quasi-dynamic method to obtain hull offset and tension of each mooring line. Finally, the fatigue life of mooring lines is predicted by T-N curve, Rainflow counting algorithm and Miner linear cumulative fatigue damage theory, together with the above results. The results show that the longitudinal distribution of the fatigue life of each mooring line is almost consistent with each other, whereas, the fatigue life is relatively short on top and touch-down point. In addition, the fatigue damage of mooring line is affected largely by the swell in West Africa, which should be paid more attention in the design of the mooring system.