Optimizing distribution of multiple tuned mass dampers for building structures with inverse element exchange method

Multiple tuned mass dampers(MTMDs)reduce dynamic response with multiple specified frequencies of building structures.Many optimization algorithms for placement design exist,though they rarely conform to code-based verification nor produce high quality solutions without high computational effort and high complexity.This study proposes an inverse element exchange method(IEEM)with multi-level programming and compares it to a single tuned mass damper(STMD)and uniform distribution of multiple tuned mass dampers in the frequency and time domains.A ten-story shear building is used for the numerical case study.The results show that the proposed method can offer improvement over the STMD,uniform distribution of multiple tuned mass dampers,and distribution optimized by genetic algorithms(GA)with regard to minimizing the interstory drift ratio(IDR)in both the frequency and time domains and the time consumption for optimization.

Seismic control of multi-degrees-of-freedom structures by vertical mass isolation method using MR dampers

Vertical mass isolation(VMI)is one of the novel methods for the seismic control of structures.In this method,the entire structure is assumed to consist of two mass and stiffness subsystems,and an isolated layer is located among them.In this study,the magnetorheological damper in three modes:passive-off,passive-on,and semi-active mode with variable voltage between zero and 9 volts was used as an isolated layer between two subsystems.Multi-degrees-of-freedom structures with 5,10,and 15 floors in two dimensions were examined under 11 pairs of near field earthquakes.On each level,the displacement of MR dampers was taken into account.The responses of maximum displacement,maximum inter-story drift,and maximum base shear in controlled and uncontrolled buildings were compared to assess the suggested approach for seismic control of the structures.According to the results,the semi-active control method can reduce the response by more than 12%compared to the uncontrolled mode in terms of maximum displacement of the mass subsystem of the structures.This method can reduce more than 16%and 20%of the responses compared to the uncontrolled mode in terms of maximum inter-story drift and base shear of the structure,respectively.

Theoretical and Experimental Study on the Performance of Hermetic Diaphragm Squeeze Film Dampers for Gas-Lubricated Bearings

Low damping characteristics have always been a key sticking points in the development of gas bearings.The application of squeeze film dampers can significantly improve the damping performance of gas lubricated bearings.This paper proposed a novel hermetic diaphragm squeeze film damper(HDSFD)for oil-free turbomachinery supported by gas lubricated bearings.Several types of HDSFDs with symmetrical structure were proposed for good damping performance.By considering the compressibility of the damper fluid,based on hydraulic fluid mechanics theory,a dynamic model of HDSFDs under medium is proposed,which successfully reflects the frequency dependence of force coefficients.Based on the dynamic model,the effects of damper fluid viscosity,bulk modulus of damper fluid,thickness of damper fluid film and plunger thickness on the dynamic stiffness and damping of HDSFDs were analyzed.An experimental test rig was assembled and series of experimental studies on HDSFDs were conducted.The damper fluid transverse flow is added to the existing HDSFD concept,which aims to make the dynamic force coefficients independent of frequency.Although the force coefficient is still frequency dependent,the damping coefficient at high frequency excitation with damper fluid supply twice as that without damper fluid supply.The results serve as a benchmark for the calibration of analytical tools under development.

Development and Application of a Power Law Constitutive Model for Eddy Current Dampers

Eddy current dampers (ECDs) have emerged as highly desirable solutions for vibration control due to theirexceptional damping performance and durability. However, the existing constitutive models present challenges tothe widespread implementation of ECD technology, and there is limited availability of finite element analysis (FEA)software capable of accurately modeling the behavior of ECDs. This study addresses these issues by developing anewconstitutivemodel that is both easily understandable and user-friendly for FEAsoftware. By utilizing numericalresults obtained from electromagnetic FEA, a novel power law constitutive model is proposed to capture thenonlinear behavior of ECDs. The effectiveness of the power law constitutive model is validated throughmechanicalproperty tests and numerical seismic analysis. Furthermore, a detailed description of the application process ofthe power law constitutive model in ANSYS FEA software is provided. To facilitate the preliminary design ofECDs, an analytical derivation of energy dissipation and parameter optimization for ECDs under harmonicmotionis performed. The results demonstrate that the power law constitutive model serves as a viable alternative forconducting dynamic analysis using FEA and optimizing parameters for ECDs.

Seismic Resilience Analysis of a Concrete-Framed Hospital Building with Viscous Dampers

To study the seismic resilience of a concrete-framed hospital building with viscous dampers,the elastoplastic time history analysis of a three-story concrete-framed hospital building under moderate and rare earthquakes was carried out by finite element analysis software.The structure’s overall response was studied,meanwhile,the seismic resilience of the building was evaluated from three aspects:repair cost,repair time,and casualties.The results show that viscous dampers can effectively reduce the repair cost,repair time,and casualties under earthquakes.Compared with the structure without dampers,the repair cost and repair time of the structure with dampers have been reduced by 67%and 69%respectively under moderate earthquakes,42%and 39%respectively under rare earthquakes,and the seismic resilience grade has been increased from zero to one star.

基于性能谱设计的被动消能减震结构易损性分析

建设韧性城市的实质是实现城市灾后的可修复和自修复功能,消能减震技术为提高城市韧性、实现可持续发展提供了新思路。基于性能谱设计方法,提出一种适用于中低层框架结构的减震设计方法,将结构阻尼参数、响应及地震动参数结合起来,通过改变结构性能参数达到控制其响应的目的;并采用该方法对一6层Benchmark钢框架结构进行减震设计,对比分析在远场和近场有、无明显脉冲地震动记录下,减震设计前后结构不同损伤状态下的易损性。结果表明:在弹性阶段,近场非脉冲和脉冲型地震动记录下的结构响应基本一致,且略大于远场地震动记录下;在弹塑性至倒塌阶段,近场非脉冲型地震动记录下的结构响应大于远场地震动记录下;相比于远场和近场非脉冲型地震动记录,近场脉冲型地震动记录更容易引起结构的破坏甚至倒塌。基于性能谱减震设计方法设计的结构,其抗倒塌能力在远场、近场非脉冲和近场脉冲型地震动记录下分别提高了44.8%、43.8%和45.6%,进一步说明该减震设计方法受地震动记录的影响非常小。

速度放大型电涡流扭矩阻尼器的缓速性能研究

由于展开速度过快,旋转机构展开到预定形态时常引起机构与限位装置碰撞而造成损坏,如SpaceX公司生产的猎鹰9号火箭在折叠支腿展开过程中,过大转角速度可能导致支腿销铰破坏.加装阻尼器可减缓机构转速,提升展开安全性,是火箭稳定着陆的前提与保证.传统位移型阻尼器不具备速度适应能力,在应用于机构展开时存在展开卡死风险;而传统高压油液阻尼器在高速运作下易引发漏液造成失效.电涡流扭矩阻尼器作为一类新型的速度型阻尼器,可用于减缓机构转动角速度,具有不需外接电源、无工作流体、耐久性强等优势,但因永磁体与导体板的相对运动速度小导致其耗能效率不高,限制了其在工程中的应用.为加强传统复合管电涡流阻尼器性能,本文提出了一种磁路优化后的复合管电涡流扭矩阻尼器.相较于传统的复合管电涡流阻尼器,本文提出的阻尼器有更小的磁漏和安装体积,此外,加入齿轮增速装置提升其工作转速,进一步提升耗能性能.基于COMSOL分析软件建立了电涡流扭矩阻尼器的有限元模型,分析了空气间隙、导体管厚度、背铁厚度等参数对扭转阻尼系数的影响;同时考虑安装空间尺寸,推导了电涡流阻尼力计算公式,提出了复合管电涡流扭矩阻尼系数估算公式.制造了速度放大型电涡流扭矩阻尼器样机和展开机构原理验证装置,并进行了冲击缓速性能测试.研究结果表明,对于特定的阻尼器参数,合理地对永磁体及导体板的厚度取值,能获得较大的扭转阻尼系数;本文提出的阻尼系数估算方法能精确描述速度放大型电涡流扭矩阻尼器在阻尼线性段的力学性能;采用质量为12 kg左右的阻尼器样机可将试验展开机构在最不利工况下的最终动能耗散效率达41.6%,具有较强耗能效率优势.

含改进LuGre摩擦的斜楔减振器斜碰撞动力学分析

针对货车转向架用斜楔摩擦减振器,引入改进LuGre动摩擦,通过简化得到一类含动摩擦及间隙的3自由度斜碰撞振动系统,建立系统的力学模型,得到系统的运动方程,并分析系统的运动状态及其条件。通过数值仿真分析外激励频率变化时系统运动的转迁过程以及黏滞、颤振现象。结果表明:在一定参数下,随着激振频率的变化,系统发生周期倍化分岔、逆周期倍化分岔以及Neimark-Sacher分岔,系统运动存在“周期泡”现象。当系统激振频率在4.4至4.6之间时,系统运动中存在颤振和黏滞现象;当系统激振频率在4.6至5.9之间时,黏滞现象消失,只存在颤振现象。

海上浮式风机纵摇及其抑制研究进展

梳理了风浪荷载单独作用与联合作用下浮式风机的纵摇响应规律,总结了调谐质量阻尼器、波浪能利用装置以及船用减摇设备等外加阻尼装置对浮式风机的减摇效果,揭示了不同减摇措施的作用机理,指出了各装置未来在控制策略、布置形式以及应用对象等研究中仍需要解决的问题。

有轨电车弹性车轮尖啸噪声分析及阻尼器设计

针对有轨电车通过曲线段时的尖啸噪声问题,文章提出了一种基于实车数据先验的弹性车轮噪声阻尼器设计方法。对某有轨电车进行小曲线线路噪声测试,获取相应的噪声主频,并建立弹性车轮有限元模型,分析噪声主频对应的车轮模态,从而确定阻尼器设计方向;建立弹性车轮尖啸噪声阻尼器动力学模型,对弹性车轮噪声阻尼器结构进行设计;建立有阻尼器的弹性车轮模型,通过声辐射分析,研究阻尼器的降噪效果。结果表明:相比无阻尼器的弹性车轮,有阻尼器的弹性车轮的辐射噪声明显降低,其在两个尖啸噪声频率处的辐射声功率级分别降低8.5 dB和6.6 dB,总声功率级降低6.8 dB。最后,为验证有限元模型的准确性,进行模态试验验证,结果表明,前11阶仿真模态频率的平均误差为3.07%,模型较为准确可靠。

铰链结构颗粒阻尼防振锤及输电线振动控制研究

为解决微风振动所造成的输电线疲劳破坏、低频振动吸收不明显问题,提出一种新型柔性约束颗粒阻尼防振锤结构,并研究其对输电线振动控制效果。设计一种铰链结构,将导线的振动传导至防振锤并起到将防振锤横向位移放大的效果,为通过颗粒阻尼充分耗能提供有利条件;通过柔性约束颗粒和防振锤腔体灵活设计,增强防振锤中颗粒间的摩擦耗能,进而实现对输电线振动的抑制。在实验室中搭建防振锤-输电线实验平台,分析防振锤对输电线振动控制特性。研究结果表明:带有铰链结构防振锤在保持线夹处动弯应变不变的情况下,具有更好的低频振动抑制效果;所设计的新型柔性颗粒铰链防振锤对于输电线的振动控制效果明显,且具有抑制宽频振动特性。研究结果可为输电线的微风振动控制以及新型防振锤的设计提供新的思路和技术途径。

柴油机激励下的机车车体振动控制研究

为了对柴油机激励下的机车车体振动进行控制,利用SIMPACK建立考虑柔性车体的机车动力学模型,并对模型的可行性进行验证;利用SIMULINK建立经典地棚阻尼控制器和基于模糊控制的地棚阻尼控制器,通过联合仿真对机车车体振动进行控制及其对比分析。结果表明:相比于刚性车体,考虑柔性车体的机车模型仿真数据与现场实测数据吻合度更高;在机车静止状态下,两种控制策略都有一定的效果,但模糊地棚阻尼器振动控制效果比经典地棚阻尼器振动控制效果更佳,其车辆平稳性和舒适度指标分别改善16.67%和46.79%;机车在正常运行状态下,随着机车运行速度的提高,柴油机对车体振动的贡献比例逐渐减小,对于柴油机减振支座的控制效果逐渐减弱,但在实际运行速度范围内,改善效果仍较明显。

双阻尼模型调谐质量阻尼器在随机激励下的减震性能研究

该文提出黏滞阻尼与滞变阻尼共同作用的双阻尼模型调谐质量阻尼器(Dual Damping Tuned Mass Damper,DD-TMD),并对白噪声作用下DD-TMD进行减震优化研究。讨论了DD-TMD的构成、优势和应用范围,并总结了DD-TMD的力学机理。提出适用于DD-TMD的H_(2)优化方法,并通过数值寻优得到了最优参数和基于稳定区域的DD-TMD参数优化方法。此外,通过DD-TMD的H_(2)优化方法进一步得到了DD-TMD的等效附加黏滞阻尼比,为工程设计奠定应用基础。以变摩擦摆式调谐质量阻尼器(Variable Friction Pendulum Tuned Mass Damper,VFP-TMD)为DD-TMD的实际应用算例,通过20条地震波检验所提出的优化方法对地震激励的减震性能影响。结果表明:H_(2)优化下的DD-TMD可以提供与常规黏滞阻尼TMD相当的控制效果。采用DD-TMD可以通过随机理论成功模拟与常摩擦阻尼等效的黏滞阻尼,并为带有初始摩擦的VFP-TMD提供有效可靠的优化设计方法。相较于前人所做的数值寻优方法,按照DD-TMD模型优化的VFP-TMD可以提供更加优异的减震控制效果且阻尼耗能能力提高了16.6%。

负刚度惯性阻尼器控制高层结构振动的试验与模拟研究

建立了控制多自由度高层建筑风致振动的负刚度惯性调谐阻尼器(negative stiffness-tuned viscous mass damper, NS-TVMD)系统的理论模型,通过3D打印技术设计制造了以齿轮齿条式惯容器元件和预压弹簧式负刚度元件组装而成的NS-TVMD系统,并将该系统安装在一个6自由度高层建筑气动弹性模型上进行了风洞试验研究。然后通过数值模拟和试验结果相互验证,并分析得到了NS-TVMD的最优参数。结果表明,准确调谐的NS-TVMD系统比传统调谐惯性黏滞阻尼器系统对高层建筑的风致振动具有更好的控制效果。由于负刚度组件在静态情况下具有高刚度,而在动态情况下具有低刚度,当NS-TVMD系统被调频至受控结构的一阶自振频率附近时,它不仅能有效控制结构的一阶模态响应,还能通过其低动态刚度特性控制结构的高阶模态响应。

基于线性累积损伤模型的硅油减振器寿命预测分析

以某重型柴油机硅油减振器为研究对象,将硅油劣化作为损伤参量,建立了硅油减振器线性累积损伤模型。基于发动机台架混合循环和负荷循环耐久试验结果,对减振器寿命模型进行标定。结合实测道路载荷谱,实现了减振器在实际使用场景下的使用寿命预测。结果表明,在牵引车工况下,基于混合循环和负荷循环试验预测的M60减振器寿命分别为1.425×10^(6) km和2.896×10^(6) km,均满足发动机寿命里程要求。

粘滞阻尼器研究进展

本研究整理并总结了国内外学者在粘滞阻尼器方面取得的大量研究成果,包括粘滞阻尼器在减震(振)领域的发展历程与研究现状,通过阻尼力公式分析的性能影响因素、粘滞阻尼器的试验研究以及工程应用实例等几方面,提出了一种新型自复位弹簧粘滞阻尼器,用于木结构的振动控制与结构复位。

耗能型胶合木墙体力学性能研究

为改善胶合木剪力墙刚度大、延性低、耗能差的问题,设计了3种胶合木墙内布置软钢阻尼器的耗能型胶合木墙体,通过数值模拟的方法分析了墙体内不同阻尼器的设置方案对胶合木墙体承载力、延性、耗能性能的影响。结果表明,沿墙体内竖向安装软钢阻尼器的耗能型胶合木墙体刚度较大、承载力较高,延性及耗能能力均显著提高,具有较高的工程应用价值。

基于MFAC-ILC的PAM-MRB柔性膝关节的仿真与试验研究

【目的】针对气动人工肌肉(Pneumatic Artificial Muscle,PAM)与磁流变阻尼器(Magnetorheological damper,MRB)复合结构的非线性对PAM-MRB膝关节运动轨迹的跟踪精度的影响,提出一种无模型自适应控制(Model-Free Adaptive Control,MFAC)结合迭代学习控制(Iterative Learning Control,ILC)算法的方法。【方法】首先,结合气动肌肉与磁流变阻尼器的力学模型,推导出PAM-MRB柔性膝关节的动力学模型;其次,利用无模型自适应控制结合迭代算法设计出无模型自适应迭代控制器(Model-Free Adaptive Iterative Controller,MFAC-ILC),并使用Matlab软件对所提控制方法的有效性进行仿真验证;最后,搭建样机平台对提出的控制方法进行试验验证。【结果】结果表明,MFAC-ILC比比例、积分、微分(Proportion,Integral,Differential,PID)控制有着更好的控制效果,控制误差降低5°左右;相较于PID控制,MFAC-ILC对PAM-MRB柔性膝关节有着更快的轨迹跟踪收敛速度,跟踪误差降低了2°,并且避免了因为膝关节建模准确性问题带来的轨迹跟踪误差。

矿井提升系统纵向振动的磁流变阻尼器减振悬挂装置设计

为抑制矿井提升系统的纵向振动,设计了一种基于磁流变阻尼器的纵向振动减振悬挂装置。首先,建立了磁流变阻尼器力学模型,并对减振悬挂阻尼器进行了结构设计和磁路设计。其次,基于多物理场仿真软件COMSOL建立了磁流变阻尼器的多物理场耦合模型,在电磁场、流场的流-固耦合环境下分析了内部磁场、流场和压力分布状况,验证了机械结构和磁路分布设计的合理性。然后,通过耦合电磁场、流场和力场的动力学仿真,得到了磁流变阻尼器在正弦激励下的阻尼力F与位移x、频率f、振幅A、电流I和阻尼可调系数β之间的关系特性;仿真结果表明,在工作电流为0~1.4 A时,所设计阻尼器的最大阻尼力为4 993 N,最大阻尼可调系数为9.97。最后,试制样机验证了所设计的磁流变阻尼器可为减振悬挂装置提供所需的阻尼力,实现矿井提升系统纵向振动的抑制。

发动机阻尼器-球轴承单元动态特性试验机

为验证阻尼器-球轴承单元动态特性理论模型,设计了一种模拟该单元运行工况的专用试验机,详细介绍了试验机的总体设计方案、主体结构、驱动系统、润滑系统、加载系统、电气系统、计算机监控系统等,并完成了试验机主轴强度、刚度及模态校核。通过试验得到了轴承转速为6000,9000,13000 r/min时的内、外圈轴心轨迹以及油膜压力,结果表明,当转速从6000 r/min增大到13000 r/min时,内、外圈轴心轨迹趋于稳定,油膜压力增幅在10%以内,与理论分析结果一致,达到了试验机设计目的,同时也验证了理论模型的正确性。