基于BCALoD的FPSO软刚臂系泊系统疲劳分析

Fatigue Analysis of FPSO Soft Yoke Mooring System Based on BCALoD

针对软刚臂系泊系统铰节点在服役过程中出现的疲劳损伤问题,提出一种基于原型监测和局部密度双向聚类算法(Bidirectional Clustering Algorithm based on Local Density,BCALoD)的疲劳寿命计算方法。采用BCALoD算法对获得的船体六自由度进行工况分类,运用多体动力学将运动数据转算为受力时程,将其作为铰节点疲劳寿命分析的载荷谱。采用Abaqus软件建立各铰节点有限元模型以计算热点应力,结合Miner线性疲劳累积损伤理论和雨流计数方法计算疲劳寿命。进一步分析评估基于实测数据的铰节点疲劳设计指标,指出该FPSO软刚臂上铰节点的疲劳寿命不足以支持其完成服役,且各铰节点难以统一维护和更换。本研究可为在役软刚臂系泊系统的疲劳寿命计算提供一种新的载荷处理方法,为未来海洋平台的设计提供参考。

A fatigue life calculation method based on prototype monitoring and Bidirectional Clustering Algorithm based on Local Density(BCALoD)is proposed for the fatigue damage problem of the hinge joints of soft yoke mooring system during service.The obtained six degrees of freedom of the hull are classified by the BCALoD algorithm in terms of working conditions.The motion data are converted into force time history using multi-body dynamics,which are used as the load spectrum for fatigue life analysis of the hinge joints.The hot spot stresses are calculated by establishing the finite element model of each hinge joint through Abaqus software,and the fatigue life is calculated by combining the Miner linear fatigue cumulative damage theory and the rainflow counting method.The fatigue design indexes of the hinge joints based on the measured data are further analyzed and evaluated,and it is pointed out that the fatigue life of the hinge joints on the Floating Production Storage and Offloading(FPSO)soft yoke mooring system is not sufficient to support its completion of service,and it is difficult to maintain and replace each hinge joint uniformly.The study can provide a new load treatment method for fatigue life calculation of in-service soft yoke mooring system,which provides reference for future design of offshore platforms.