Vibration attenuation performance of wind turbine tower using a prestressed tuned mass damper under seismic excitation

With the rapid development of large megawatt wind turbines,the operation environment of wind turbine towers(WTTs)has become increasingly complex.In particular,seismic excitation can create a resonance response and cause excessive vibration of the WTT.To investigate the vibration attenuation performance of the WTT under seismic excitations,a novel passive vibration control device,called a prestressed tuned mass damper(PS-TMD),is presented in this study.First,a mathematical model is established based on structural dynamics under seismic excitation.Then,the mathematical analytical expression of the dynamic coefficient is deduced,and the parameter design method is obtained by system tuning optimization.Next,based on a theoretical analysis and parameter design,the numerical results showed that the PS-TMD was able to effectively mitigate the resonance under the harmonic basal acceleration.Finally,the time-history analysis method is used to verify the effectiveness of the traditional pendulum tuned mass damper(PTMD)and the novel PS-TMD device,and the results indicate that the vibration attenuation performance of the PS-TMD is better than the PTMD.In addition,the PS-TMD avoids the nonlinear effect due to the large oscillation angle,and has the potential to dissipate hysteretic energy under seismic excitation.

Multiple Tuned Mass Damper Based Vibration Mitigation of Offshore Wind Turbine Considering Soil–Structure Interaction

The dynamics of jacket supported offshore wind turbine （OWT） in earthquake environment is one of the progressing focuses in the renewable energy field. Soil-structure interaction （SSI） is a fundamental principle to analyze stability and safety of the structure. This study focuses on the performance of the multiple tuned mass damper （MTMD） in minimizing the dynamic responses of the structures objected to seismic loads combined with static wind and wave loads. Response surface methodology （RSM） has been applied to design the MTMD parameters. The analyses have been performed under two different boundary conditions： fixed base （without SSI） and flexible base （with SSI）. Two vibration modes of the structure have been suppressed by multi-mode vibration control principle in both cases. The effectiveness of the MTMD in reducing the dynamic response of the structure is presented. The dynamic SSI plays an important role in the seismic behavior of the jacket supported OWT, especially resting on the soft soil deposit. Finally, it shows that excluding the SSI effect could be the reason of overestimating the MTMD performance.

Suppression of Wave-Excited Vibration of Offshore Platform by Use of Tuned Liquid Dampers

This paper describes experimental and theoretical investigations of Tuned Liquid Damper (TLD) characteristics for suppressing the wave-excited structural vibration. The structural model for the experiments is scaled according to a full size offshore platform by matching their dynamic properties. Rectangular TLDs of different sizes with partially filled liquid are examined. By observing the performance and behavior of TLDs through laboratory experiments, the Study investigates the influence of a number of parameters, including container size, container shape, frequency ratio, and incident wave characteristics. In an analytical study, a mathematical model that describes the nonlinear behavior of liquid in TLD and the interaction of TLD and structure is prerequisite. The validity of the model is evaluated and simulating results can reasonably match the corresponding experimental results.

Experimental study of vibration mitigation of mast arm signal structures with particle-thrust damping based tuned mass damper

Large amplitude vibration of mast arm structures due to wind loads are the primary contributing factor to the reduced fatigue life of signal support structures. To alleviate this problem of wind-induced in-plane vibration of mast arm signal structures, a particle-thrust damping based turned mass damper(PTD-TMD) device is adopted and its damping effect is characterized experimentally. The particle-thrust damping is a passive damping device that does not require electric power and is temperature independent. Based on the calibration test, an equivalent dynamic model of the PTD-TMD device is developed and used for numerical simulation study. The damping effects of this PTD-TMD device on signal support structures was investigated through both numerical analysis and laboratory testing of a 50-ft(15.24 m) mast arm structure including both free vibration and forced vibration tests. The experimental test and numerical study results show that vibration response behavior of mast arm signal support structures can be significantly reduced by installing the PTD-TMD that can increase the critical damping ratio of the mast arm signal structures to 4%. The stress range at the welded connection between the mast arm and traffic pole is also reduced.

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

ne purpose of this study is to investigate the effectiveness of multi-tuned mass dampers (MTMD) on mitigating vibration 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 without MTMD on the structure is made under design conditions. 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 better the vibration control.

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.

Variable stiffness tuned particle dampers for vibration control of cantilever boring bars

This research proposes a novel type of variable stiffness tuned particle damper(TPD)for reducing vibrations in boring bars.The TPD integrates the developments of particle damping and dynamical vibration absorber,whose frequency tuning principle is established through an equivalent theoretical model.Based on the multiphase flow theory of gas-solid,it is effective to obtain the equivalent damping and stiffness of the particle damping.The dynamic equations of the coupled system,consisting of a boring bar with the TPD,are built by Hamilton’s principle.The vibration suppression of the TPD is assessed by calculating the amplitude responses of the boring bar both with and without the TPD by the Newmark-beta algorithm.Moreover,an improvement is proposed to the existing gas-solid flow theory,and a comparative analysis of introducing the stiffness term on the damping effect is presented.The parameters of the TPD are optimized by the genetic algorithm,and the results indicate that the optimized TPD effectively reduces the peak response of the boring bar system.

Wind-induced vibration control of bridges using liquid column damper

The potential application of tuned liquid column damper (TLCD) for suppressing wind-induced vibration of long span bridges is explored in this paper.By installing the TLCD in the bridge deck,a mathematical model for the bridge-TLCD system is established.The governing equations of the system are developed by considering all three displacement components of the deck in vertical,lateral,and torsional vibrations,in which the interactions between the bridge deck,the TLCD,the aeroelastic forces,and the aerodynamic forces are fully reflected.Both buffeting and flutter analyses are carried out.The buffeting analysis is performed through random vibration approach,and a critical flutter condition is identified from flutter analysis.A numerical example is presented to demonstrate the control effectiveness of the damper and it is shown that the TLCD can be an effective device for suppressing wind-induced vibration of long span bridges,either for reducing the buffeting response or increasing the critical flutter wind velocity of the bridge.

Parameters Optimization and Performance Evaluation of the Tuned Inerter Damper for the Seismic Protection of Adjacent Building Structures

In order to improve the seismic performance of adjacent buildings,two types of tuned inerter damper(TID)damping systems for adjacent buildings are proposed,which are composed of springs,inerter devices and dampers in serial or in parallel.The dynamic equations of TID adjacent building damping systems were derived,and the H2 norm criterion was used to optimize and adjust them,so that the system had the optimum damping performance under white noise random excitation.Taking TID frequency ratio and damping ratio as optimization parameters,the optimum analytical solutions of the displacement frequency response of the undamped structure under white noise excitation were obtained.The results showed that compared with the classic TMD,TID could obtain a better damping effect in the adjacent buildings.Comparing the TIDs composed of serial or parallel,it was found that the parallel TIDs had more significant advantages in controlling the peak displacement frequency response,while the H2 norm of the displacement frequency response of the damping system under the coupling of serial TID was smaller.Taking the adjacent building composed of two ten-story frame structures as an example,the displacement and energy collection time history analysis of the adjacent building coupled with the optimum design parameter TIDs were carried out.It was found that TID had a better damping effect in the full-time range compared with the classic TMD.This paper also studied the potential power of TID in adjacent buildings,which can be converted into available power resources during earthquakes.

Seismic Response Reduction for Fixed Offshore Platform by Tuned Liquid Damper

An approach to seismic response reduction for offshore platforms by the use of the tuned liquid damper is presented in this paper. First of all, the effects of the tuned frequency ratio and excited frequency ratio on the seismic response reduction of the platform structure are investigated. Based on the results, a mechanical model and equation of motion for the TLD-platform system are established. And then effectiveness of the appraoch is verified by numerical calculation.

Torsionally Coupled Response Control of Offshore Platform Structures Using Circular Tuned Liquid Column Dampers

In this paper, the control performance is investigated of Circular Tuned Liquid Column Dampers (CTLCD) over torsional response of offshore platform structures excited by ground motions. Based on the equation of motion for the CTLCD-structure system, the optimal control parameters of CTLCD are given through some derivations on the supposition that the ground motion is a stochastic process. The influence of systematic parameters on the equivalent damping ratio of the structures is analyzed with purely torsional vibration and translational-torsional coupled vibration, respectively. The results show that the Circular Tuned Liquid Column Damper (CTLCD) is an effective torsional response control device.

Fuzzy-entropy based robust optimization criteria for tuned mass dampers

Tuned mass dampers (TMD) are well known as one of the most widely adopted devices in vibration control passive strategies. In the past few decades,many methods have been developed to find the optimal parameters of a TMD installed on a structure and subjected to a random base excitation process,but most of them are usually based on an implicit assumption that all of the structural parameters are deterministic. However,in many real cases this simplification is unacceptable,so robust optimal design criteria becomes aviable alternative to better support engineers in the design process. In Robust Design Optimization (RDO) approaches,indeed the solution must be able to not only minimize the performance but also to limitits variation induced by uncertainty. Most of the currently available RDO methods are based on a probabilistic description of the model uncertainty,even if in many cases they are not able to explicitly include the influence of all the possible sources of uncertainties. Therefore,in this study,a fuzzy version of the robust TMD design optimization problem is proposed. The consistency of the fuzzy approach is studied with respect to the available non-probabilistic formulations reported in the literature and an application to an example of a robust design of a linear TMD subjected to base random vibrations in the presence of fuzzy uncertainties. The results show that the proposed fuzzy-based approach is able to give a set of optimal solutions both in terms of structural efficiency and sensitivity to mechanical and environmental uncertainties.

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.

Reliability based multiobjective optimization for design of structures subject to random vibrations

Based on a multiobjective approach whose objective function (OF) vector collects stochastic reliability performance and structural cost indices, a structural optimization criterion for mechanical systems subject to random vibrations is presented for supporting engineer’s design. This criterion differs from the most commonly used conventional optimum design criterion for random vibrating structure, which is based on minimizing displacement or acceleration variance of main structure responses, without considering explicitly required performances against failure. The proposed criterion can properly take into account the design-reliability required performances, and it becomes a more efficient support for structural engineering decision making. The multiobjective optimum (MOO) design of a tuned mass damper (TMD) has been developed in a typical seismic design problem, to control structural vibration induced on a multi-storey building structure excited by nonstationary base acceleration random process. A numerical example for a three-storey building is developed and a sensitivity analysis is carried out. The results are shown in a useful manner for TMD design decision support.

Distributed TLDs in RC floors and their vibration reduction efficiency

A novel distributed tuned liquid damper （DTLD） for reducing vibration in structures is proposed in this paper. The basic working principle of the DTLDs is to fill the empty space inside the pipes or boxes of cast-in-situ hollow reinforced concrete （RC） floor slabs with water or other liquid. The pipes or boxes then work as a series of small TLDs inside the structure, to increase the damping ratio of the entire structural system. Numerical simulation that accounts for the fluid- structure conpling effect is carried out to evaluate the vibration-reduction efficiency of the DTLDs. The results show that the DTLDs are able to considerably increase the damping of the structure and thus reduce its vibration. An additional benefit is that the DTLDs do not require architectural space to be added to the structure.

Analysis of Impact of Tuned Damper Floating Fastener on Track System

Ground-borne noise caused by track vibration became one of major problem affecting urban rail transit development. Resilient rail fasteners come to be a main measure of reducing ground-borne noise. Low stiffness of fastener contributes to ensuring the good effect of vibration isolation, but causing higher vibration of rails, while the tuned damper fastener can make it up. In this paper, the simulation of rail receptance is used to fit on site measured data, then the data are used to build a vehicle-track-foundation model to do the calculations, like vibration reduction of track systems and rails. According to the results, the tuned damper fastener can reduce the vibration of slab as well as rails.

悬索桥竖弯涡振MTMD减振控制效果和参数优化研究

为研究多重调谐质量阻尼器(Multiple Tuned Mass Damper,MTMD)抑制桥梁单阶涡振的性能,建立桥梁结构-MTMD系统竖弯涡振广义单自由度动力方程,以某大跨度悬索桥为背景进行MTMD减振控制效果和参数优化分析。采用数值方法求解动力方程,获得系统在简谐涡激力下达到稳态谐振时结构的动力放大系数和MTMD对结构的附加模态阻尼比,并与单一频率调谐质量阻尼器(Single Tuned Mass Damper,STMD)的减振控制效果进行对比,然后以附加模态阻尼比为目标对MTMD进行参数优化。结果表明:MTMD比最优参数STMD拥有更宽的控制频带和更好的减振效果,经优化后的MTMD减振性能优于最优参数STMD。实际应用MTMD时,应选择较大广义质量、5~7种频率规格,并根据二者找到无量纲频率范围和各TMD阻尼比的惟一最优取值。

基于多目标灰狼算法的漂浮式风电机组浮台内TMD参数优化

针对漂浮式风电机组浮台内调谐质量阻尼器(TMD)参数调优的问题,以5 MW Barge型漂浮式风电机组为研究对象,采用多目标灰狼算法(MOGWO)优化TMD参数配置。首先,基于欧拉-拉格朗日方程建立浮台内含TMD的漂浮式风电机组动力学模型,采用Levenberg-Marquardt(LM)法进行模型未知参数辨识;其次,同时考虑塔顶和塔基控制目标,采用MOGWO算法优化TMD的刚度和阻尼参数;最后,在不同工况下进行仿真分析。结果表明:相对于传统的单目标优化算法,使用MOGWO算法参数优化后的TMD对风电机组具有更好的振动抑制效果。

双重电磁谐振式调谐质量阻尼器的参数优化及对结构减振分析

利用电磁阻尼单元代替经典调谐质量阻尼器中的黏性阻尼单元,形成一种具有结构减振功能的新型电磁谐振式调谐质量阻尼器(electromagnetic shunt tuned mass damper,EMS-TMD)。为进一步提升阻尼器的减振性能和鲁棒性,设计了双重电磁谐振式调谐质量阻尼器(DEMS-TMD)减振方案。依据达朗伯定理,建立地震作用下DEMS-TMD与单自由度结构耦合振动系统的动力学模型。利用蒙特卡洛-模式搜索法数值优化方法,以主结构位移的动力放大系数最大值最小为目标函数,优化得到DEMS-TMD的结构频率比、电子频率比、电磁阻尼比和机电耦合系数的最优参数,为减振参数设计提供理论指导。通过频域和时域两种方法仿真分析了DEMSTMD对结构的减振性能。结果表明:在频域分析中,DEMS-TMD的主结构位移峰值和频响面积均优于传统并联双调谐质量阻尼器(double tuned mass damper,DTMD);在时域分析中,DEMS-TMD对结构位移、加速度峰值和均方根的减振性能均优于传统DTMD,有效地提高了对结构的减振效果。

风浪联合作用下分布式调谐质量阻尼器对海上半潜漂浮式风机的减振控制

海上半潜漂浮式风机在复杂深海环境下产生有害振动会威胁风机的安全性和耐久性,针对该问题并结合美国NREL的5 MW样机的漂浮平台几何结构构造,提出利用分布式调谐质量阻尼器(Tuned Mass Dampers,TMDs),即分别在漂浮平台的3根浮筒中布置TMD,形成等边三角形布置,对随机风浪联合作用下海上半潜漂浮式风机的平台纵摇振动进行控制。为了更好地描述分布式TMDs对海上半潜漂浮式风机的减振效果,基于拉格朗日方程和模态叠加法,对海上半潜漂浮式风机-TMDs耦合系统提出并建立了9自由度多体动力学模型。基于H_(∞)算法,即以平台纵摇频响函数的峰值为优化目标,对分布式TMDs的参数进行优化设计,优化设计中考虑了3个TMDs之间的耦合关系。对风机-TMDs耦合系统开展了风浪联合作用下的数值模拟,分析了分布式TMDs对平台纵摇响应的减振效果。结果表明:最优设计下的分布式TMDs对海上半潜漂浮式风机平台纵摇振动具有良好的减振性能;在三种不同工况的随机风浪荷载作用下,分布式TMDs对平台纵摇固有频率附近的功率谱密度曲线峰值减振率和标准差减振率能分别达到39%和52%以上。