极端海况下海洋立管的动态可靠性分析

Study of Marine Riser Dynamic Reliability under Extreme Sea Conditions

运用ANSYS有限元模拟软件,以一海洋立管为模型,采用Morison方程结合Stokes五阶波理论计算波浪力。研究了海洋立管在波浪、海流载荷同时作用下的动力可靠性。利用格拉马-沙尔勒叶级数拟合法分别对海洋立管在三种极端海况下最大米塞斯等效应力响应的分布密度函数进行求解,获得其概率密度分布模型。利用数值积分,采用应力-强度模型计算海洋立管的动态可靠度。分析结果表明:当海况严峻程度增大时,结构的最大米塞斯等效应力随之增大,海洋立管的动态可靠度随之减小,失效概率随之增大。研究结果可以为极端海况下海洋立管的可靠性评估和安全开发提供了一定的理论依据和重要的参考价值。

ANSYS finite element simulation software is used to a marine riser model. Meanwhile, wave force is calculated by using Morison equation combined with the fifth-order Stokes wave theory. Then marine riser dynamic reliability under the action of wave and ocean current load is studied. By Gram-Charlier series fitting on the marine riser maximum Von-Mises equivalent stress response to obtain density function probabilistic model. Using numerical integration and stress-intensity model to compute the dynamics reliability of the marine riser, the result shows that when the sea conditions severity increases, the maximum Von-Mises equivalent stress of structure increases, marine risers dynamic reliability decreases, the probability of failure increases. Results of this study can provide a theoretical basis and an important reference value for the marine riser reliability assessment and safety develop under the extreme sea conditions.