规则波下张力腿平台时域响应分析

讨论规则波下某张力腿平台的动力响应时域运动特性。着重分析入射波角度(15°,22.5°和45°),波高(6m,8m和10m)及波周期(10s,12s和14s)对张力腿平台各自由度运动、顶端张力的影响。探讨吃水高度、工作水深、不同张力腿数目对张力腿平台运动特性的影响。计算结果表明:由于张力腿平台各自由度对入射波角度、波高和波周期敏感度不同,张力腿平台在不同波浪参数下的运动特性(如位移幅值、平衡位置等)及顶端张力表现各异;不同吃水下的张力腿平台位移大小、平衡位置和运动方向等均不同。工作水深越大,各自由度运动越剧烈,这体现了工作环境对张力腿平台运动具有较大影响。张力腿数目越多,张力腿平台运动的位移、幅度等越小,随时间变化也越稳定。     

Dynamic response analysis of a small-scale model tension leg platform

Experimental tests performed on a hydroelastic small-scale model of a tension leg platform for deep water are reported. Comparison between the processed experimental dynamic signals and theoretical responses obtained with a simplified six degrees of freedom model are made. Moreover, some effects of fluid-structure interaction are briefly discussed in the light of results from both impact and wave loading tests.     

Frequency domain analysis of a tension leg platform with statistical linearization of the tendon restoring forces

The dynamics of a tension leg platform have important nonlinearities which must be approximated in some manner in a frequency domain analysis. For irregular waves, the well-documented method of statistical linearization is commonly employed for the drag forces, but it is seldom applied to the restoring forces. In earlier studies, the stiffness linearization has been limited to the surge motion. This paper presents the formulation for the linearization in all six degrees-of-freedom. To this end, the nonlinear restoring function and tangent stiffness matrix are derived, and extensive nonlinear couplings between the different modes are found to exist. The performance of the linearized frequency domain approach is benchmarked against time domain simulations for a problem involving large platform motions. It is found that subject to certain conditions, which are relatively mild, the linearization technique facilitates accurate predictions of the mean offsets and the response variances, including the slow-drift component.     

基于SESAM软件的张力腿平台疲劳强度分析

以张力腿平台为研究对象,建立有限元模型,通过对结构进行总体强度分析,确定疲劳关键区域和关键点。然后建立关键区域的局部模型,对局部模型的网格划分方法进行研究,利用SESAM软件中的Sestra模块计算应力传递函数。最后基于Stofat模块,采用线性外推法得到疲劳关键点处的热点应力,根据S-N曲线,计算出结构的疲劳寿命。结果表明,张力腿平台的疲劳强度满足设计寿命要求。     

张力腿平台钻井设备模块准静力分析

基于某深海张力腿平台结构,采用SESAM软件建立该平台的水动力分析计算模型,通过计算得到该平台的RAO和极值加速度;进而采用ANSYS软件建立该平台上部钻井设备模块分析计算模型,以惯性力的形式考虑平台运动对上部结构强度分析产生的影响,并对钻井设备模块进行准静力分析,为张力腿平台这类移动式平台上部设备模块结构的强度分析提供研究思路和技术支持。     

基于SESAM软件的张力腿平台疲劳强度分析

以张力腿平台为研究对象,建立有限元模型,通过对结构进行总体强度分析,确定疲劳关键区域和关键点。然后建立关键区域的局部模型,对局部模型的网格划分方法进行研究,利用SESAM软件中的Sestra模块计算应力传递函数。最后基于Stofat模块,采用线性外推法得到疲劳关键点处的热点应力,根据S-N曲线,计算出结构的疲劳寿命。结果表明,张力腿平台的疲劳强度满足设计寿命要求。     

An approximate method for the surge response of the tension leg platform

The solution for the Duffing equation in anonlinear vibration problem is studied in this paper. Clearly,in the case of the perturb parameter being a larger value, thetraditional perturbation method is no longer valid but theHomotopy Perturbation Method （HPM） is applicable usually.HPM is used to solve the weak and strong nonlineardifferential equations for finding the perturbed frequency ofthe response. The obtained frequencies via HPM and theapproximate method have good accordance for weak andstrong nonlinear differential equations. Additionally, thecalculated responses by use of the approximate method arecompared with the responses obtained from the Numericalmethod in the time history of the response and phase plane.The results represent ~ood accordance between them.     

张力腿平台系泊风险评估方法研究

文章结合模糊综合评判法、层次分析法以及概率论提出了一种风险分析的评估方法,识别了系泊中的风险因素,建立完善了相应的风险评估指标体系,并将其应用于设计中或已服役作业的张力腿平台系泊风险评估。将不同风险评估结果视为风险的总体的随机样本,用概率论和置信区间对风险评估结果进行置信度评价。克服了单一评价方案主观性太强的弱点,使评价更具有客观性和可信性。经过分析和计算实例表明,该系泊风险评估方法是适用和有效的。利用获取的评价结果,识别设计或已建成服役的张力腿平台系泊风险指数高的风险因素,并采取有效措施,加强培训及时检修设备,以防止意外的发生。结合一型设计中的张力腿平台,应用文中提出的数值风险评估模型对该平台的系泊系统进行了风险评估。结果表明该方法可以对张力腿平台的系泊风险评估中的主观因素进行客观有效的评估。并可以推广应用于其他海上结构物的风险评估问题中。     

海上浮式风机张力腿平台的水动力响应

以美国某可再生能源所的海上5 MV风机为模型,结合风机塔柱的特点,利用Orca Flex建立了一种海上风机张力腿平台简化模型。通过时域耦合计算方法和傅里叶变换,得到了该系统的动力学响应,对比并分析了在考虑涡激振动和不考虑涡激振动时各个张力腿的动力学变化和平台的水动力响应。     

基于动态刚度阵法的海洋平台动力响应分析

导管架式海洋平台是人类开发和利用海洋资源的重要工程设施,动态刚度阵法是解决工程中结构振动问题的一个强有力的工具,其可以通过较少的单元数计算出结构固有频率和固有振型,减少结构的自由度数,随着计算频率的升高,DSM法无需进一步细化单元.本文应用DSM法建立导管架式海洋平台模型,将导管架式海洋平台简化成平面刚架结构,计算了导...     

半潜式平台耦合动力响应分析

由于海洋这一特殊的环境,半潜式平台在海上会受到风、浪、流的联合作用,使得半潜式平台产生六自由度方向的运动,影响平台的作业,因此,进行平台运动响应预报及系泊线强度校核就显得尤为重要。本文选择在1 000 m水深的情况下,分别在时域和频域条件下对半潜式平台运动响应进行数值模拟,预报在频域和时域条件下半潜式平台运动响应,并对比分析在时域条件下不同风、浪、流组合工况下平台升沉运动幅值,计算设计的平台系泊线拉力,并进行强度校核。     

半潜式平台耦合动力响应分析

由于海洋这一特殊的环境,半潜式平台在海上会受到风、浪、流的联合作用,使得半潜式平台产生六自由度方向的运动,影响平台的作业,因此,进行平台运动响应预报及系泊线强度校核就显得尤为重要。本文选择在1000 m水深的情况下,分别在时域和频域条件下对半潜式平台运动响应进行数值模拟,预报在频域和时域条件下半潜式平台运动响应,并对比分析在时域条件下不同风、浪、流组合工况下平台升沉运动幅值,计算设计的平台系泊线拉力,并进行强度校核。     

基于稳定性理论的张力腿平台横摇固有周期分析

文章以稳定性理论为基础提出了一种张力腿平台横摇固有周期计算模型,分析了横摇临界角对平台横摇稳定性的影响,并将其应用于分析平台设计参数对横摇固有周期的影响。提出在一个横摇周期里,最后稳定横摇临界角对应的时间历程为1/4横摇固有周期这一假设,基于此假设,编制计算机计算程序,计算横摇运动中每一个横摇角,判断其稳定性,找出一个横摇周期内最后稳定横摇临界角对应的时间历程,求解横摇运动固有周期。考虑两种横摇阻尼情况,计算不同初始横摇角、横摇下沉位移、张力腱长度、平台重量和横摇阻尼的横摇固有周期,论证了平台设计参数对横摇固有周期的影响。该计算模型克服了从结构角度计算固有周期工作量大、计算周期长、计算结果不可靠的弱点,使横摇固有周期计算简单、有效。通过与不考虑横摇阻尼的情况对比,分析了横摇阻尼对横摇固有周期的影响。可以快速计算处于设计阶段或者已服役张力腿平台横摇固有周期。结合一型设计中的张力腿平台,应用文中提出的横摇固有周期计算模型对该平台进行了横摇固有周期的计算,并且分析了平台参数对横摇固有周期的影响。结果表明该方法可以对张力腿平台横摇固有周期进行快速计算。并可推广应用于其它海上结构物的横摇固有周期计算。     

张力腿平台涡激运动特性的试验研究

文章基于物理模型试验,对张力腿平台的涡激运动问题进行了探讨,研究了横向和顺流向涡激运动频率及响应特性。试验结果表明:在锁定区,涡激运动频率与平台在海流中的位置有关。当结构沿流向对称时,顺流向振荡频率是横向振荡频率的两倍;当结构沿流向不对称时,顺流向振荡频率与横向振荡频率相同。试验结果还表明,流向角是影响平台运动轨迹的关键因素,当流向角为0°和45°时,平台运动轨迹呈不规则"8"字形;15°和30°时,运动轨迹为"香蕉形"。     

基于Orcaflex的张力腿网箱水动力分析

基于凝集质量法和等效网目法对网衣进行等效处理,利用大型水动力分析软件Orcaflex建立张力腿网箱模型,求解分析张力腿网箱在在波浪作用、海流作用和波-流联合作用3种外载荷情况下浮于水面和下沉时系泊缆有效张力的变化情况。分析结果可作为张力腿网箱安全建设的理论依据,对张力腿网箱模型在海洋工程中的应用具有一定的参考价值。     

新建半潜运输船在张力腿平台运输方面的应用研究(英文)

Transportation of tension leg platform(TLP) structures for a long distance has always been associated with the use of a heavy semi-transport vessel.The requirements of this type of vessel are always special,and their availability is limited.To prepare for the future development of South China Sea deepwater projects,the China Offshore Oil Engineering Corporation has recently built a heavy lift transport vessel-Hai Yang Shi You 278.This semi-submersible vessel has a displacement capacity of 50k DWT,and a breath of 42 meters.Understanding the vessel’s applicability and preparing it for use in future deepwater projects are becoming imminent needs.This paper reviews the current critical issues associated with TLP transportation and performs detailed analysis of the designed TLP during load-out and transportation.The newly built COOEC transportation vessel HYSY 278 was applied to dry transport of the TLP structure from the COOEC fabrication yard in Qingdao to an oil field in South China Sea.The entire process included the load-out of the TLP structure from the landsite of the fabrication yard,the offloading and float-on of the platform from the vessel,the dry transport of the TLP over a long distance,and the final offloading of the platform.Both hydrodynamic and structure analysis were performed to evaluate the behavior of the transport vessel and TLP structure.Special attention was paid to critical areas associated with the use of this new vessel,along with any potential limitations.The results demonstrate that HYSY 278 can effectively be used for transporting the structure with proper arrangement and well-prepared operation.The procedure and details were presented on the basis of the study results.Special attention was also given to discussion on future use based on the results from the analysis.     

系泊系统非线性恢复力研究及其应用(英文)

Mooring system plays an important role in station keeping of floating offshore structures.Coupled analysis on mooring-buoy interactions has been increasingly studied in recent years.At present,chains and wire ropes are widely used in offshore engineering practice.On the basis of mooring line statics,an explicit formulation of single mooring chain/wire rope stiffness coefficients and mooring stiffness matrix of the mooring system were derived in this article,taking into account the horizontal restoring force,vertical restoring force and their coupling terms.The nonlinearity of mooring stiffness was analyzed,and the influences of various parameters,such as material,displacement,pre-tension and water depth,were investigated.Finally some application cases of the mooring stiffness in hydrodynamic calculation were presented.Data shows that this kind of stiffness can reckon in linear and nonlinear forces of mooring system.Also,the stiffness can be used in hydrodynamic analysis to get the eigenfrequency of slow drift motions.     

深海系缆动张力的超谐动力响应

文章考虑深水系缆的拉伸和弯曲变形,取正交坐标和切向量描述任意结点的6个广义位移,考虑缆变形的几何非线性和水动力影响,基于细长杆理论推导缆索的单元刚度矩阵,引入单元内张力一致假设,推导出12×12的非线性刚度矩阵,并与有限元软件对接。针对1800m水深平台的系缆,考虑系缆端点垂荡运动,以及端点垂荡、横荡和海流作用两种状态下系泊系统的动力响应。计算结果表明,端点运动和海流作用,引起系缆系统的二倍超谐动力响应,并且随着流速增大,系缆超谐动力响应增大,系缆的超谐动张力分量对于缆索疲劳累积损伤具有重要影响,在系缆疲劳分析时应该予以考虑。     

考虑桩土非线性作用的近海风机高桩平台地震响应分析

分别建立全斜桩承台与全直桩承台三维有限元模型,研究了地震荷载作用下桩基的动力响应。考虑了地震引起的水体惯性力对动力响应的影响,并通过引入p-y曲线修正系数考虑了桩基倾斜对桩轴垂向桩土作用的影响。结果表明,在单桩的情况下,地震动水压力对桩基的弯矩与位移存在明显的放大效应;不同单桩的位移反应峰值发生在同一时刻,倾斜方向与峰值时刻地震加速度方向一致的桩承载性能最优。对于带承台的群桩,地震动水压力的放大效应没有单桩时明显,各个方位斜桩以及直桩之间弯矩与位移差异较小;直桩的位移峰值大于斜桩,而斜桩弯矩均较直桩在泥面以下处有一定的减小,但在承台交界面处较直桩更大。     

桩基建模方法对自升式钻井平台动力响应的影响

随着海洋油气开采作业水深的不断增加,海洋平台固有频率随之降低,易与相同频率成分的波浪产生共振,因此对平台动力响应特性研究是非常有必要的,而桩基模型在平台动力响应分析中发挥着关键作用。以某400英尺自升式钻井平台研究对象,基于等效建模的思想,分别建立了固支桩基、铰接桩基、线性弹簧桩基及非线性弹簧桩基四种有限元模型,并对其进行静力分析、模态分析及瞬态动力学分析,通过对比得到的振动频率、动力放大因子及波流惯性力,得出弹簧桩基模型在平台动力响应分析中的有效性及合理性结论。