参数激励下深海立管多模态耦合振动特性分析  

Multi-mode coupled vibration behavior of a deep-water riser under parametric excitations

作　　者：张杰[1] 唐友刚[1] 黄磊[1] 李伟[1] 

机构地区：[1]天津大学水利工程仿真与安全国家重点实验室,天津300072

出　　处：《振动与冲击》2013年第19期51-56,共6页Journal of Vibration and Shock

基　　金：国家自然科学基金资助项目(51079097);国家自然科学基金创新研究群体科学基金(51021004)

摘　　要：由于浮体升沉运动影响,引起立管在水平方向上发生参数激励振动。参激振动可以引起平衡位置的不稳定性,如果系统参数组合落在不稳定区域,将加剧立管振动破坏。针对简谐参数激励,建立立管横向振动方程,考虑立管内部张力沿轴线变化,立管固有频率和振型发生变化,参激振动出现模态耦合效应。采用Floquet理论分析了立管无阻尼和有阻尼时的参激稳定性,计算了临界参数激励下的动力响应。与单模态参激振动对比表明,同等阻尼下,模态耦合参激振动不稳定区域显著增大,更易发生参激共振。多模态耦合参激振动发生时,小激励也能激起大响应,特别是弯曲应力将显著增大。The heave of a floating platform induces a fluctuation of axial tension of a riser. This fluctuation as an excitation may cause a transverse parametric vibration of the riser. Parametric vibration may destabilize the equilibrium of the riser and cause it to vibrate at a dangerously high level. Tension in the riser is typically assumed to be constant over the length, but the tension actually varies linearly from the top to the bottom due to the effect of gravity, it leads to coupling among the modes of the riser. Here, firstly the governing motion equation of a deep-water riser under harmonic parametric excitations was formulated. Then, considering the coupling among the modes of the riser, the stability behavior of the riser with and without damping was investigated by using Floquet theory, and the dynamic response of the riser under critical parameters was obtained. The results showed that the unstable zone for the multi-mode coupled system significantly grows, and a small excitation can excite large responses, especially, the bending stress increases significantly.

关 键 词：深海立管 参数激励 模态耦合 动力响应 

分 类 号：TE58[石油与天然气工程—油气田开发工程] O323[理学—一般力学与力学基础]