【作者】 谢文会；

【导师】 唐友刚；

【作者基本信息】 天津大学 ， 船舶与海洋结构物设计制造， 2007， 博士

【摘要】 铰接塔平台为适应水深100m～500m的顺应式平台,可用于单点系泊、装载终端、控制塔、海底安装等生产环节。铰接塔平台承受非线性海洋载荷作用,其摇摆运动特性和运动稳定的研究对于确保平台的安全具有重要的意义。本文应用非线性动力学理论和方法,研究了铰接塔平台复杂海洋环境作用下的非线性运动特性和运动稳定性,以及单点系泊铰接塔的运动特性及系泊张力的冲击特性。本文的工作和主要结论如下:　(1)全面综述了铰接塔平台动力响应研究的进展和现状,确定了本文的研究方向和关键研究问题。　(2)建立了铰接塔塔柱刚性运动动力学模型,应用Morison公式计算水动力,依据拉格朗日原理建立了铰接塔平台强非线性运动方程。分别考虑波浪作用和波流联合作用,研究了铰接塔平台超谐共振、亚谐共振、组合共振、混沌运动。研究表明,波浪作用下平台系统将出现2、3、5…倍超谐共振,　2 vm +vn组合共振,波流联合作用下平台系统将出现2、3、4、5…倍超谐共振,v m + vn组合共振、2 vm + vn组合共振,在特定波浪载荷下平台系统会发生1/2亚谐共振,在高频率波浪激励下平台系统会出现混沌运动。　(3)考虑铰接塔塔柱弹性变形,应用Morison公式计算平台瞬时位置的水动力,建立了铰接塔平台摇摆运动的偏微分方程,采用伽辽金方法求解波流作用下非线性动力响应。研究表明,波浪激励下铰接塔二阶模态将发生2、3、4倍超谐共振,弹性铰接塔在波浪作用下振动是不对称的。使用有限元方法计算了不同环境载荷条件下铰接塔的动力学响应,验证了本文简化模型的合理性。　(4)提出用增量谐波平衡法,结合Floquet理论和增量弧长法研究铰接塔-油轮分段线性恢复刚度,平方阻尼系统的方法。研究了系统超谐、亚谐、谐波、组合谐波解,幅频特性和分岔、混沌特性。用最大Lyapunov　指数图验证了三种由倍周期分岔导致的混沌运动,用内插胞映射的方法验证了混沌运动和稳定周期解共存以及系统运动对初值极度敏感的非线性动力学现象。　(5)基于铰接塔-油轮系统运动响应,分析了该系统系泊力变化特性。研究表明,在相同状态参数条件下系泊力具有多种不同的响应,当系统受到扰动,系统运动的形式极易发生突变,系泊力响应在不同响应中跳跃,由此可以初步解释铰接塔-油轮系统系泊力的突变机理。更多还原

【Abstract】 The articulated tower platform(ATP) is the a kind of compliant platform designed for water depths of 100 to 500 m, it is used as single point mooring or as loading terminals, control towers, seabed installation facilities. The ATP suffers from nonlinear ocean environment loads, the study of swing motion and motion stability of ATP is very important for safety of the platform. In this paper, the theory and method of nonlinear dynamics are adopted to study the nonlinear dynamic behavior and motion stability of the ATP under complicated environment loads. In addition, the motion behavior of single point mooring articulated tower and the impact property of mooring force are studied. The main work and the conclusions obtained are as following:(1) The research development and current state of the nonlinear dynamics of ATP at abroad and home is summarized synthetically. The study direction and key problems of the thesis are presented.(2) The dynamics model of rigid body of ATP is put forward considering non-elastic tower, the hydrodynamic force is evaluated for the ATP by using Morison formula, the highly nonlinear motion equation is established according to Lagrange principle. Sup-harmonic resonance, sub-harmonic resonance, combination-harmonic resonance and chaos motion of ATP were investigated using numerical method with considering wave loads and combined wave-current loads respectively. The results show that the sup-harmonic resonance of orders 2,3,5…and 2 v m +vn combination-harmonic resonance will occur under wave loads; sup-harmonic resonance of orders 2,3,4,5…, v m + vn and 2 v m +vn combination-harmonic resonance will occur under combined wave-current loads; sub-harmonic resonance of order 1/2 was found in certain case under wave loads; Chaotic motion was found under high frequency wave excitation.(3) Considering elastic deformation of the tower, the hydrodynamic force is evaluated at the instantaneous position of ATP using Morison formula, the partial differential equation of swing motion is established. The nonlinear response of ATP is calculated by Galerkin’s method. The results show that the second mode of ATP arises sup-harmonic resonance of orders 2,3,4 , and the unsymmetry of the motion of ATP is found under wave excitation. The dynamical response of ATP and the moment variety of tower are analyzed under different environmental loads by the finite element method, and the simplified model is validated in this paper.(4) The calculation methods using incremental harmonic balance method, Floquet theory and incremental arc length method are presented for nonlinear dynamical response of ATP-Tanker considering piecewise linear restoring force and square damping. Sup-harmonic, sub-harmonic, harmonic, combination harmonic response, amplitude frequency characteristic and the behaviors of bifurcation and chaos are studied. Three kinds of chaotic motion caused by period doubling bifurcation in this system are verified by the max Lyapunov exponent diagram. The coexistence of chaos and stable period motion, and the sensibility of system motion depending on the initial value are explained by the interpolated cell mapping method.(5) Based on the response of ATP-Tanker system, the varying characteristic of mooring force is studied. It is found that there are many different mooring force responses for the same set of system parameters, the abrupt change occurs easily in the motion of the system when it is perturbed and the mooring force response jumps among the several different values. This can primarily explain the mechanism of the abrupt change of the mooring force for the ATP-Tanker system.更多还原