深水钢悬链线立管顺流向非线性动力分析

Nonlinear dynamic analysis of deepwater steel catenary riser in-line vibration

深水钢悬链线立管在外部流体作用下的动力响应在立管的性能优化设计中是非常重要的。文章考虑了深水钢悬链线立管轴向大应变的特性以及弯曲刚度和内流的影响,利用Hamilton原理和拉格朗日应变理论建立了立管的二维动力学模型。将外部流体的非线性作用力用Morison方程表示,通过Hermite插值函数对动力学方程进行离散,采用平均加速度法求解立管的动力响应。探讨了外部流体的非线性作用力对海洋立管顺流向动力响应的影响以及不同流速和拖曳力系数与海洋立管共振响应幅值的关系。

In order to carry out the performance-based design of the deepwater steel catenary risers,the evaluation of their dynamic responses to current drag force is imperative.In this study,the energy function of the risers conveying fluid is drived from variational principle.Nonlinear equations of motion influenced by the nonlinear Morison waveform are obtained through Hamilton＇s principle in combination with Lagrangian-strain definition.Investigation of the in-line dynamic responses of steel catenary risers is achieved using the finite element method and Newmark Average Acceleration Method.It is found that the current drag force and velocity play a major role in the responses,while the flow rate and drag force coefficients remarkably affect the displacement amplitudes of the marine risers＇ resonant responses.