张紧式系泊系统刚度特性及对Spar平台运动影响的研究

发布时间：2018-03-17 17:20

本文选题：材料非线性　切入点：张紧式系泊回复刚度　出处：《天津大学》2014年硕士论文　论文类型：学位论文

【摘要】：由于具有稳定良好的作业性能，深海桁架式Spar平台得到广泛应用，对于桁架式Spar平台大水深的工作环境，现今其多采用张紧式系泊系统进行定位。研究张紧式系泊系统非线性回复特性，以及在系泊作用下的平台固有运动特性和在规则波中的耦合动力响应，对平台的设计具有重要的意义。本文针对深海桁架式Spar平台，考虑了三点九根缆索张紧式系泊定位形式，研究其在六个自由度方向上的固有运动特性以及在规则波中的动力响应特性。以线性材料缆索经典悬链线理论为基础，同时考虑聚酯纤维缆索的材料非线性特性与几何非线性特性，对缆索微段静力平衡方程进行重新推导，建立了单根聚酯纤维缆索静力平衡方程。在单根缆索求解的基础上采用准静态方法计算三点系泊系统的位移-回复力变化曲线，并研究有关系泊因素对系泊系统回复刚度的影响。建立系泊平台耦合运动方程，运用数值方法求解平台各自由度固有运动特性，并讨论不同系泊条件对平台自振特性的影响。同时，建立水动力模型计算平台在规则波中的波浪载荷，计算当波浪圆频率与垂荡固有频率相接近时，平台发生垂荡主共振时的运动响应。研究表明，张紧式系泊系统在平台小幅运动下平台回复力与位移基本成线性关系，随着平台位移的增大，，系泊回复力开始表现出非线性变化；系泊条件的改变将会改变平台水平运动的固有频率。系泊系统回复刚度对于不同方向上的运动的影响程度不同。适当的系泊系统使平台在波浪中的运动响应幅值降低，但并不能阻止平台发生垂荡主共振时平台摇动幅值在某一波高下发生突变现象。三点系泊形式导致平台纵荡运动与横荡运动的固有周期不一致，从而导致在不同浪向角下平台运动幅值的不对称。
[Abstract]:Because of its stable and good working performance, deep-sea truss Spar platform is widely used. For the working environment of truss Spar platform with large water depth, Nowadays, most of the mooring systems are located by tensed-tight mooring system. The nonlinear recovery characteristics of the tensed-mooring system, the inherent motion characteristics of the platform under mooring and the coupled dynamic response in regular waves are studied. It is of great significance to the design of platform. In this paper, 3.9 cable tensioning mooring modes are considered for deep-sea truss Spar platform. Based on the classical catenary theory of linear materials, the inherent motion characteristics in six degrees of freedom and the dynamic response in regular waves are studied. At the same time, considering the material nonlinear and geometric nonlinear characteristics of polyester fiber cable, the static equilibrium equation of micro-segment of cable is rededuced. The static equilibrium equation of a single polyester fiber cable is established. Based on the solution of a single cable, a quasi-static method is used to calculate the displacement-recovery force curve of a three-point mooring system. The effect of mooring factors on the stiffness of mooring system is studied. The coupled motion equation of mooring platform is established, and the inherent motion characteristics of each degree of freedom of the platform are solved by numerical method. The influence of different mooring conditions on the natural vibration characteristics of the platform is discussed. At the same time, the hydrodynamic model is established to calculate the wave loads in regular waves, and the wave circle frequency is calculated when the wave circle frequency is close to the natural frequency of the heave. The motion response of the platform when the main pendulum resonance occurs. The results show that the recovery force and displacement of the tensioned mooring system are linear under the small motion of the platform. With the increase of the displacement of the platform, the mooring force begins to show nonlinear changes. The change of mooring condition will change the natural frequency of the horizontal motion of the platform. The effect of the mooring system recovery stiffness on the motion in different directions will be different. The appropriate mooring system will reduce the amplitude of the platform motion response in the wave. But it can not prevent the platform rocking amplitude from abrupt change at a certain wave height when the platform is swinging main resonance. The three-point mooring mode leads to the inconsistency of the inherent period between the longitudinal motion of the platform and the motion of the swinging motion. This results in the asymmetry of the amplitude of platform motion at different wave angles.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U674.381

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