Multiaxial fatigue analyses of stress joints for deepwater steel catenary risers
Multiaxial fatigue analyses of stress joints for deepwater steel catenary risers
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DOI：
10.1007/s13344-012-0053-x
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发表时间：
2012-12
影响因子：
1.6
通讯作者：
Wen Zheng;Heuiweon Yang;Qing-quan Li
中科院分区：
文献类型：
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作者：
Wen Zheng;Heuiweon Yang;Qing-quan Li
本文研究了海洋环境条件下两种应力节点的动态和疲劳特性。深水钢质悬链线立管(SCR)连接立管和平台，船舶悬挂处的应力连接应是主要的关键设计挑战之一。当立管处于高压和深水工作状态时，接头的应力状态较为复杂，在此位置容易发生疲劳损伤。本文讨论的应力节点包括锥形应力节点(TSJ)和套筒应力节点(SSJ)两种类型，并给出了多轴疲劳分析结果以供比较。首先对SCR进行整体动力学分析，然后将分析得到的局部边界条件应用于应力节点有限元模型，以进行后续的动态和多轴疲劳分析。结果表明，应力水平远低于材料的屈服极限，疲劳损伤值得关注。此外，两种应力接头的损伤特征不同：对于TSJ，应力接头与立管的连接处最容易发生疲劳损伤；对于SSJ，最有可能的位置是内套管端与立管主体接触的位置。与SSJ相比，TSJ的应力水平较高，但疲劳性能较好，材料成本较高。设计人员应综合考虑各种因素，选择最合适的型式和几何参数。
In the present study, the dynamic and fatigue characteristics of two types of stress joints are investigated under ocean environmental condition. Connected with the riser and the platform, stress joint at the vessel hang-off position should be one of the main critical design challenges for a steel catenary riser (SCR) in deepwater. When the riser is under a high pressure and deepwater working condition, the stress state for the joint is more complex, and the fatigue damage is easy to occur at this position. Stress joint discussed in this paper includes two types: Tapered Stress Joint (TSJ) and Sleeved Stress Joint (SSJ), and multiaxial fatigue analysis results are given for comparison. Global dynamic analysis for an SCR is performed first, and then the local boundary conditions obtained from the previous analysis are applied to the stress joint FE model for the later dynamic and multiaxial fatigue analysis. Results indicate that the stress level is far lower than the yield limit of material and the damage induced by fatigue needs more attention. Besides, the damage character of the two types of stress joints differs: for TSJ, the place where the stress joint connects with the riser is easy to occur fatigue damage; for SSJ, the most probable position is at the place where the end of the inner sleeve pipe contacts with the riser body. Compared with SSJ, TSJ shows a higher stress level but better fatigue performance, and it will have a higher material cost. In consideration of various factors, designers should choose the most suitable type and also geometric parameters.