顶张力立管的两向涡激振动疲劳寿命时域分析

Time Domain Analysis of TTR's Fatigue Life under Two-degrees-of-Freedom Vortex-induced Vibration

针对波浪、剪切流和平台随机激励等多因素共同作用下顶张力立管的顺流向和横向涡激振动疲劳问题,采用文圣常谱模拟随机波浪载荷、采用Ahmad多自由度动态运动方程分析平台动态响应、采用考虑流体阻尼力和附加质量影响后改进的Facchinetti尾流振子模型模拟立管激振力,建立了综合考虑波浪、海流和平台随机激励多因素影响的顶张力立管涡激振动有限元数值模拟模型,获得不同海况等级和平台作用下立管顺流向和横向涡激振动结构响应;根据Miner准则估算立管各节点累积疲劳损伤,提出了基于时域法的立管两向涡激振动疲劳寿命数值计算方法,并用该方法对我国典型海域顶张力立管进行了分析应用。此研究旨在为立管设计和在役安全评估提供技术支持。

In view of the in-line （IL） and cross-flow （CF） vortex-induced vibration of the top tensioned riser under the combined action of wave, shear flow and platform random excitation, the load of random wave was simulated using Wen Shengchang spectrum, and the dynamic response of the platform was ana- lyzed using Ahmad＇s multi-degree-of-freedom dynamic equations. In order to simulate the riser excitation force with the improved Facchinetti wake oscillator model considering the influence of fluid damping force and additional mass, a finite element numerical model of the vortex-induced vibration of the top tensioned riser considering the multi-factor effects of wave, current and platform random excitation was established. The structural responses of IL and CF vortex-induced vibration of the riser under the actions of differentsea conditions and platforms were obtained. The cumulative fatigue damage of each node of the riser was estimated according to Miner＇s rule. A numerical method for calculating the riser＇s fatigue life in two de- grees of freedom under vortex-induced vibration based on time domain was proposed, and was used in the analysis and application of the top tension riser in typical coastal waters of China. The present research is intended to provide technical support for riser design and in-service safety assessment.