Pipe bend is a common junction in pipeline system. In this study, the post-buckling behavior of deep-sea thick-walled pipe bend under external pressure is studied by numerical simulation. A 4-node tetrahedron solid element based on vector form intrinsic finite element method (VFIFE) is introduced to simulate the whole buckling process. First, the VFIFE models of the thick-walled pipes are built and the results of the VFIFE method, traditional finite element method, and the experiments from other publications are compared to verify the proposed method. Then, collapse modes and collapse mechanism of the pipe bend when buckling propagates to the elbow under dynamic and quasi-static conditions are analyzed. Finally, the influence of different geometric parameters on the crossover pressure of the pipe bend is studied. These results can be used to support the buckling arrest design of pipe bends.

弯管是管道系统中常见的连接点。本研究通过数值模拟研究深海厚壁弯管在外压作用下的后屈曲行为。引入基于矢量形式固有有限元法（VFIFE）的四节点四面体实体单元来模拟整个屈曲过程。首先，建立了厚壁管道的 VFIFE 模型，并将 VFIFE 方法、传统有限元方法和其他出版物的实验结果进行了比较，以验证所提出的方法。然后，分析了弯管在动态和准静态条件下屈曲传播到弯头时的坍塌模式和坍塌机制。最后研究了不同几何参数对弯管交叉压力的影响。