海洋柔性管道骨架层压溃的有限元分析

Finite element analysis for collapse of flexible pipes carcass

针对海洋柔性管道互锁型骨架层由于外部静水压力可能引起压溃失效问题,文中基于有限元分析方法,采用实体单元,建立骨架层结构三维有限元模型,研究静水外压作用下骨架层的压溃行为.分析结果显示,当不考虑几何缺陷及材料非线性时,计算得到的压溃特征值与解析方法得到结果吻合良好;当模型考虑初始椭圆度缺陷时,压力位移曲线经过一段线性变化过程后快速趋近于临界压溃值,且随着初始椭圆度的增大,临界压溃值逐渐减小;当模型进一步引入材料非线性时,骨架层的抗压溃能力显著下降,临界压溃值比理想状态下减小近一半.数值模型与结果为柔性管道抗压溃分析设计提供了有效的技术手段.

To effectively investigate the collapsing failure for the interlocked carcass layer of an un-bonded flexible pipe caused by a high value of external hydrostatic pressure, a three dimensional finite element model was devel-oped based on the finite element analysis method. The model was developed to simulate the collapse behavior of car-cass under hydrostatic external pressure, in which solid elements are used. Analysis results indicate that a good cor-relation between analytical and numerical calculation models was achieved for critical pressure, without considering geometrical imperfections and material nonlinearity. The pressure-displacement curve with considering initial ellipti- cal defect approaches the critical pressure rapidly after a linear developing process, and the critical pressure value goes down as the initial ovality increases. When material nonlinearity is introduced to the model, the critical pres-sure of the carcass reduces significantly and is nearly half of the original perfect one. The numerical model and re-suits provide an efficient method and basis for design and analysis of the un-onded flexible pipe collapse resistance in industry.