Flexible pipes conveying fluid commonly exist in practical engineering. Its rich dynamic behaviors have attracted remarkable attention from researchers. The standing cantilevered pipe conveying fluid with the significant gravity effect is supposed to exhibit interesting dynamic behaviors. However, since the geometric nonlinearity was approached by the Taylor expansion in the traditional theoretical model, the pipe undergoing a relatively large deformation cannot be well solved. This work develops the absolute nodal coordinate formulation (ANCF) for the standing pipe system by considering the exact geometric nonlinearity. The energy-preserving algorithm is demonstrated to be necessary for solving such an extreme dynamics system. Three states of the standing pipe including the buckling, the re-stabilizing, and the flutter are detected. Four evolutionary paths of the standing pipe system that mainly depend on the mass ratio and the gravity parameter are shown in Gantt Charts. An experimental study on the large-deformation dynamics of the standing pipe is also carried out through the self-constructed device. The critical flow values for the occurrences of the re-stabilization and the flutter states are measured. The buckling/vibrating shapes and the displacement’s time traces are recorded. By comprehensively comparing the calculated ANCF results with the measured experimental data, we have verified the correctness of the developed theoretical model and the adopted Newmark algorithm. The developed ANCF model and the conducted experiment can guide the rational design of the fluid-conveying pipe system under large deformation.

中文翻译：

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直立悬臂管道输送流体大变形动力学理论与实验研究


实际工程中普遍存在输送流体的柔性管道。其丰富的动态行为引起了研究人员的广泛关注。具有显着重力效应的直立悬臂管道输送流体应该表现出有趣的动态行为。然而，由于传统理论模型中采用泰勒展开式来逼近几何非线性，无法很好地解决管道发生较大变形时的问题。这项工作通过考虑精确的几何非线性，开发了立管系统的绝对节点坐标公式（ANCF）。能量守恒算法被证明对于求解这种极端动力学系统是必要的。检测立管的三种状态，包括屈曲、重新稳定和颤振。甘特图中显示了主要取决于质量比和重力参数的立管系统的四种演化路径。还通过自建装置对立管大变形动力学进行了实验研究。测量发生再稳定和颤振状态的临界流量值。记录屈曲/振动形状和位移的时间轨迹。通过将ANCF计算结果与实测实验数据进行综合比较，验证了所建立的理论模型和所采用的Newmark算法的正确性。所建立的ANCF模型和进行的实验可以指导大变形下流体输送管道系统的合理设计。