基于非线性能量阱的随机波浪载荷下导管架海洋平台的振动控制

海洋平台受到波浪等海洋环境的影响会产生明显而持续的振动,这些振动会造成平台结构疲劳损伤,影响平台上工作人员的舒适性与安全性。研究了随机波浪载荷作用下非线性能量阱(Nonlinear Energy Sink, NES)对固定式导管架海洋平台振动控制问题,并与调谐质量阻尼器(TMD)进行对比分析。通过建立NES—海洋平台系统动力学模型,从降低平台位移响应均方差的角度对NES的参数进行了优化设计,确定了随机波浪载荷作用下NES和TMD的最优参数。考虑结构刚度变化的问题,对NES和TMD的减振性能、系统瞬时能量传递和平台响应小波变化时频谱进行了对比分析。结果表明,NES可有效降低平台的在随机波浪载荷作用下的位移响应,NES中的瞬态共振俘获现象可使平台与NES之间产生靶能量传递(Targeted energy transfer, TET),与TMD相比较NES对刚度变化的鲁棒性更强。     

基于半仿真实验系统的调谐质量阻尼器等效阻尼力测量

为了研究调谐质量阻尼器(tuned mass damper,TMD)在海洋平台冰激振动中的减振效果,提出一种基于半仿真实验系统的TMD等效阻尼力测量方法,利用该系统可以直接测试结构安装TMD装置时产生的作用力.介绍该实验系统的测试原理及等效阻尼力的测量方法,并在正弦位移输入下,对TMD装置进行了测试,比较等效阻尼力的实测值与计算值,结果证明利用该系统可以测量得到TMD的等效阻尼力.     

基于非线性能量阱的半潜式平台垂荡响应抑制研究

半潜式平台由于吃水浅、水线面小导致垂荡响应较大,为采油树的选择以及钻井、采油等作业带来了许多制约因素,增加维护和作业成本。针对这一问题,本文提出了一种带有非线性能量阱(Nonlinear energy sink, NES)的半潜式平台结构。根据NES减振原理,将活动式垂荡板作为NES系统的具体结构,通过建立带有NES系统的半潜式平台动力学模型,以减小平台垂荡响应为目标,优化设计了NES系统参数。考虑海况变化问题,对NES系统和调谐质量阻尼器(Tuned mass damper, TMD)系统的垂荡响应抑制性能、系统能量传递进行了对比分析。结果表明：NES系统对半潜式平台的垂荡响应具有明显抑制效果,NES系统的共振俘获现象可以使平台与其发生靶能量传递(Targeted energy transfer, TET),同TMD系统相比,NES系统对不同海况波浪谱峰周期变化的鲁棒性更强。     

海洋平台结构模态参数识别的仿真研究

将特征系统实现法(ERA)与CBSI算法相结合识别海洋平台结构的模态参数(固有频率,阻尼比,振型),利用有限的加速度信号进行结构模态参数识别。海洋平台结构数值模型模拟的动力响应信号用于参数识别。所识别出的海洋平台模态参数与有限元ANSYS分析所得的结果相比较,表明运用本文所提出的方法进行模态参数识别是有效的。     

规则波作用下圆形调谐液体阻尼器的试验研究

对规则波作用下圆形调谐液体阻尼器的可行性及有效性进行了试验研究，探索调谐液体阻尼器对于固定式海洋平台结构成振的实用性。调谐液体阻尼器的减振性能通过结构响应的减小程度来评价。试验观测了容器中液体的运动形态，同时考虑容器的大小、数目，阻尼器与平台结构、波浪三者之间的频率比，质量比以及激振波浪参数等诸多因素的影响，得到了利用调谐液体阻尼器进行固定式海洋平台减振设计的具有指导意义的结论。     

浅海导管架平台结构损伤诊断试验研究

基于模型试验研究了浅海导管架平台的结构损伤诊断,采用标量型ARMA模型识别出结构的三阶模态参数,分别采用遗传算法和模态应变能法对试验模型不同模拟损伤工况进行了损伤诊断。基于遗传算法,提出了采用不同自由度一阶模态参数的损伤诊断方法。研究表明,由于海洋平台的前三阶模态分别为不同自由度的一阶模态,采用两阶或三阶模态识别损伤时,损伤杆件影响较小的自由度方向的模态参数对结构的损伤诊断将产生不利的影响,成为识别噪声。因此,可分别采用不同自由度的一阶模态进行结构损伤诊断。     

基于小波变换的固定式海洋平台结构损伤识别方法研究

小波变换在分析非平稳信号方面较傅立叶变换更有效,为了检测出海洋平台结构中裂缝或因刚度降低引起的损伤,对海洋平台的响应信号进行离散小波变换,通过分析变换后的信号是否有突变现象判断结构是否出现损伤,并结合模态应变能法实现了对结构损伤的定位,探讨了传感器位置对识别效果的影响。     

OC4漂浮式风电平台的水弹性响应及波浪载荷研究

漂浮式风电平台在波浪中的摇晃运动会导致塔架根部产生很大的弯矩,极大地威胁平台结构安全。同时流体的附连水质量效应对平台塔架结构的动响应有着较为显著的影响,因此充分考虑这种流固耦合效应有利于更加准确地评估平台塔架的结构动响应。采用三维频域线性水弹性方法计算塔架在流体作用下的结构共振频率特征以及各阶模态振动的主坐标响应特性,然后通过弹性模态叠加法获得塔架的弯矩载荷。并结合概率学手段,预报了短期极限海况下塔架弯曲载荷响应,为新一代漂浮式风电平台结构安全性评估和方案设计提供了技术支撑。     

冰激振动下简易平台的动态优化设计

简易平台是边际油田开发的主要结构形式,由于平台结构形式简单,受到动力荷载作用响应比较大。采用动态设计可以合理优化平台结构形式,达到降低平台动力响应的效果。文中以JZ20-2NW简易平台为原型,运用ANSYS有限元分析软件对其进行冰激振动下的动态优化设计。结果表明,动态设计减振效果明显,可供设计人员参考。     

基于BP神经网络的深水自升式海洋平台智能控制模型试验研究

基于BP神经网络控制方法设计了一种适用于自升式海洋平台的智能控制系统。为了验证该控制系统的有效性,以墨西哥湾海域某典型深水自升式海洋平台为原型,根据动力相似准则按照1∶40的相似比设计海洋平台试验模型,采用磁流变阻尼器作为实施该智能控制方法的控制器,并对其主要参数进行了设计。在此基础上,在波浪水池中分别对有、无安装控制系统的自升式海洋平台模型进行了多工况的波浪试验,通过对比安装控制系统前后平台结构的响应幅度,研究了控制系统的振动控制效果。试验结果表明:基于BP神经网络的磁流变阻尼智能控制系统能够有效地控制自升式海洋平台结构的动力响应,且控制效果稳定。     

Offshore Structural Control Considering Fluid Structure Interaction

1.IntroductionAmong various control devices,Tuned Mass Damper(TMD)has been mostfrequently usedtothecontrol of structural vibration induced by oscillating loads such as earthquakes,winds,and waves.This is due to the fact that it operates without external e…     

海洋平台基于隔振锥体装置的减振效应研究

针对导管架式海洋平台结构型式与特点,利用冲击隔振理论,将冰锥体与隔振技术结合起来,提出一种能有效降低冰荷载激励的"两级柔性隔振锥体"设计方案。建立了两极隔振锥体简化计算模型,确定了系统振动传递系数参数之间的关系。通过建立海洋平台有限元模型,采用有限元程序,进行了模拟冰荷载激励下的振动响应分析,并对安装隔振装置的小比例模型结构进行了冲击荷载下的减振试验。结果表明采用"两级柔性隔振锥体"能有效降低传递给海洋平台的冰力极值,减小海洋平台冰激励的响应。     

Long-Term Effect of TMD on Vibration Control of An MDOF Offshore Fixed Platform

A three-dimensional fixed offshore platform in deep water modeled by the finite element method is studied in this paper. Analysis of the dynamic response of the MDOF structure is realized taking the non-linearity of the wave drag force and the wave-structure interaction into account. The structural response statistics, which have Gaussian distributions, are used to evaluate the vibration effect of the structure without TMD and with TMD. And an optimal method to design TMD controlling the first mode of the multi-mode structure is proposed. Moreover, the probabilities of occurrence of sea states at the platform site are considered for prediction of the long-term effect of a TMD. Simulation results demonstrate that the long-term effect of a well-designed TMD is good and the practical use is possible due to the good stability of its optimal parameters under different sea states.     

Mitigation of Ice-Induced Vibrations for Offshore Platforms Using Tuned Mass Damper

The problems of ice-induced vibration have been noticed and concerned since the 1960s, but it has not been well resolved. One reason is that the dynamic interaction between ice and structure is so complicated that practical ice force model has not been developed. The recent full-scale tests conducted on jacket platforms in the Bohai Sea presented that ice could cause intense vibrations which endanger the facilities on the deck and make discomfort for the crew. In this paper, the strategy of mitigation of ice-induced offshore structure vibration is discussed. Based on field observations and understanding of the interaction between ice and structure, the absorption mitigation method to suppress ice-induced vibration is presented. The numerical simulations were conducted for a simplified model of platform attached with a Tuned Mass Danlper （TMD） under ice force function and ice force time history. The simulation results show that TMD can fa- vorably reduce ice-induced vibrations, therefore, it can be considered to be an alternative approach to utilize. Finally, the application possibilities of utilizing TMDs on other miniature offshore structures in ice-covered areas of marginal oil fields are discussed.     

Vibration Control of Multi-Tuned Mass Dampers for An Offshore Oil Platform

The purpose of this study is to investigate the effectiveness of multi-tuned mass dampers (MTMD) on mitigating vi-bration of an offshore oil platform subjected to ocean wave loading. An optimal design method is used to determine the optimal damper parameters under ocean wave loading. The force on the structure is determined by use of the linearized Morison equation. Investigation on the deck motion with and vvithout MTMD on the structure is made under design condi-tions. The results show that MTMD with the optimized parameters suppress the response of each structural mode. The sensitivity of optimum values of MTMD to characteristic wave parameters is also analyzed. it is indicated that a single TMD on the deck of a platform can have the best performance, and the small the damping value of TMD, the betler the vibration control.     

Energy Anaiysis for TMD-Structure Systems Subjected to Impact Loading

This paper investigates the characteristics of reduction of the lateral vibration by use of a Tuned Mass Damper (TMD) for offshore jacket platforms under impact loading. Unlike traditional analysis, the present analysis focuses on the energy concept of TMD/structure systems. In this study, a time domain is taken. The platform is modeled as a simplified single-degree-of-freedom (SDOF) system by extraction of the first vibration mode of the structure and the excited force is assumed to be impact loading. The energy dissipation and energy transmission of the structure-TMD system are studied. Finally, an optimized TMD design for the modeled platform is demonstrated based on a new type of cost function - maxi-mum dissipated energy by TMD. Results indicate that TMD control is effective in reducing the Standard deviation of the deck motion but less effective in reducing the maximum response under impact loading.     

海洋平台磁流变阻尼器控制技术研究

为了更有效地减小海洋平台动力响应,采用基于模糊控制算法的磁流变阻尼器对海洋平台的振动进行控制.以海洋平台位移响应误差和误差变化为输入变量,以最优控制力为输出变量,优化设计出模糊控制器.考虑实际磁流变阻尼器输出控制力上限存在限制,采用半主动控制算法计算接近于最优控制力的半主动控制力.以一固定式海洋平台为算例研究磁流变阻尼器的振动控制效果及其模糊性,仿真结果表明模糊磁流变控制器对于平台的振动可以实现非常有效的控制,且控制效果对结构阻尼和环境的不确定性具有较好的模糊性.     

Energy Analysis for TMD-Structure Systems Subjected to Impact Loading

This paper investigates the characteristics of reduction of the lateral vibration by use of a Tuned Mass Damper(TMD) for offshore jacket platforms under impact loading. Unlike traditional analysis, the present analysis focnses on theenergy concept of TMD/structure systems. In this study, a time domain is taken. The platform is modeled as a simplifiedsingle-degree-of-freedom (SDOF) system by extraction of the first vibration mode of the structure and the excited force isassumed to be impact loading. The energy dissipation and energy transmission of the structure-TMD system are studied.Finally, an optimized TMD design for the modeled platform is demonstrated based on a new type of cost function - maxi-mum dissipated energy by TMD. Results indicate that TMD control is effective in reducing the standard deviation of thedeck motion but less effective in reducing the maximum response under impact loading.     

基于实测数据的海上风电结构动力响应分析

地震是危害海上风电结构作业安全的重要环境因素,目前,国内尚未公开发表真实地震响应下,海上风电结构的实测动力响应数据。分析了某地震活动区海上风电结构的实测地震响应,采用随机子空间识别方法进行风机的模态识别,阐述了风机机舱偏航将引起前后、左右两个正交方向振动的耦合,并从理论上证明了利用耦合、解耦数据识别模态参数的差异。结果表明：1）耦合与解耦信号识别的频率、阻尼比完全相同,而耦合信号识别的模态振型与偏航角有关;2）地震作用会对结构产生巨大冲击;3）非地震作用下,风机塔筒前后、左右第一阶弯曲模态为主要模态,地震作用可以激发风机的高阶模态,使得塔筒中上部而不是顶部的振动响应最大。此分析对地震活动区海上风电结构的抗震设计具有一定的参考价值。