磁流变阻尼器的两种力学模型和试验验证

本文根据我们设计制作出的磁流变阻尼器的阻尼特性试验结果，提出了描述阻尼器动态特性的两种新的力学模型。一种称之为修正的Bingham模型，它由Bingham单元（库仑摩擦单元与粘滞单元并联）与弹簧单元串联组成。该弹簧单元与磁流变液屈服前区的初始剪切模量和蓄能器的刚度等有关。另一种称为修正的Dahl模型，它采用Dahl模型来模拟库仑摩擦力，克服了常用的Bouc-Wen模型需要确定的参数过多的缺点。为了使模型在阻尼器的电流强度（磁场强度）改变的情况下仍然有效，引入一个内变量描述模型参数与电流强度（磁场强度）的关系。最后，通过理论分析与试验结果的比较，证明本文提出的两种力学模型能够较为精确地描述大多数的磁流变阻尼器在改变电流强度（磁场强度）情况下的动态特性。     

足尺磁流变阻尼器的建模及动态特性

在过去三十年左右的时间里,结构保护系统受到了广大研究者的普遍关注.这种保护系统可以用来降低自然灾害(如地震、强风)对上木工程建筑的损害.由于磁流变阻尼器机械结构简单,动态范围大,能耗低,回复力大,鲁棒性良好,能够在满足不同工程项目需求的同时提供有效的结构抗震抗风手段,目前它是一种非常有前途的半主动结构减震装置.本文首先介绍了磁流变液体和装置的主要特性和优点,建立了磁流变阻尼器的伪静力轴对称模型,并将其结果和平行板模型以及阻尼器实验结果进行了比较.尽管伪静力模型对于阻尼器的设计十分有效,但是它们还不足以描述阻尼器的动态特性.对实际工程应用来说,动态响应时间是一项非常重要的性能指标.文章还讨论了影响磁流变阻尼器动态响应时间的因素,建立了基于Bouc-Wen模型的阻尼器动态模型.同时文章也提出了优化阻尼器动态响应的途径和方法以及其实验验证.     

可调滞回模型的磁流变阻尼器及其试验

本文在现在磁流变阴尼器性能研究的基础上，提出了可调滞回模型的磁流变阻尼器及其试验方法，并进行理论、试验及算例分析。首先，根据恒定电流下磁流变阻尼器的阻尼力滞力特性，利用磁流变材料特性的电流（即磁场）可控特点，建立了变电流下的阻尼力滞回模型；其次，在中通过电路板控制外加电流与装置变形间的函数关系，实现了变电流调节的阻尼力滞回模型；最后，将磁流变阻尼器与橡胶隔震装置结合，形成智能磁流变隔夺装置，并对一个单自由度隔震结构进行了数值仿真分析。     

逆变型磁流变阻尼器的实验和分析

磁流变液是一种性能优良的智能材料,用其制成的MR阻尼器是一种理想的半主动控制装置。本文提出了一种新型MR阻尼器——逆变型MR阻尼器,给出了逆变型MR阻尼器的设计方法,并设计了一个足尺的阀式逆变型MR阻尼器。实验证明逆变型MR阻尼器阻尼力可调,在电源失效或无电源时能够在大阻尼状态工作,这提高了半主动控制装置在地震中的使用安全性。逆变型MR阻尼器具有良好的可靠性、实用性和经济性。本文最后针对试验中阻尼器出力的可调范围比较小的问题给出了几种改进的思路。     

基于非线性模型的TLD参数优化

高柔结构在强风或地震等环境荷载作用下，往往会产生较大的变形和位移。采用调谐液体阻尼器对结构进行控制时，需要选择合适的水箱尺寸和水深，以期获得最好的减振效果。以往的调谐液体阻尼器参数优化往往基于等效线性模型或在小幅值激励下有较好精度的非线性浅水波动模型。采用了一种具有非线性阻尼和非线性刚度的等效调谐质量阻尼器模型对影响调谐液体阻尼器减振效率的主要参数进行了优化，该模型不再受小幅值激励的限制。优化结果表明，激励幅值对TLD的最优参数和减振效果有明显影响，同时水箱长度对TLD减振效果也有明显影响，这是基于线性模型TLD优化不能得到的结论。     

基于自供电磁流变阻尼器的隔震高架桥半主动控制

为解决结构振动控制的能量源问题,提出了一种新型自供电MR阻尼器智能减振系统。该系统由电磁调节式MR阻尼器、齿条齿轮加速器、永磁电机与控制器组成。基于广泛采用的隔震高架桥两自由度线性模型,定义了位移控制性能评价指标,引入了在汽车悬架系统设计中常用的Sky-hook控制策略,对隔震高架桥的减震性能进行了仿真分析。结果表明:通过优化设计的参数,自供电MR阻尼器的LQR-Clipped半主动控制与Skyhook控制都可以完全达到其相应的采用外部供电的MR阻尼器的控制效果,且接近理想的主动控制结果。     

基于H∞理论的磁流变阻尼器半主动容错控制

建筑结构的半主动控制系统中的传感器,在强震作用下可能因出现故障而影响控制效果。以磁流变阻尼器为例,研究半主动容错控制系统的设计方法。首先,研究了基于状态观测器的半主动H∞控制器设计方法,并将之应用到建筑结构采用磁流变阻尼器的减振控制中;运用改进Bouc-Wen模型,计算磁流变阻尼器的阻尼力,通过求解一个代数Riccati方程和一个状态观测方程,得出了基于状态观测器的H∞主动控制律;再对其采用Clipped-optimal方法实施半主动控制策略。然后,针对传感器故障,利用观测器组的输出残差对故障进行在线诊断,并通过几个观测器状态值的比较得到故障的大小,并据此对传感器的测量值进行修正,从而消除故障对闭环系统的影响,最终实现半主动H∞容错控制。仿真结果表明,该方法具有很好的容错控制效果。     

基于磁流变阻尼器的层间隔震结构半主动控制研究

提出了一种层间隔震结构的半主动控制模型,建立了其振动控制方程,采用磁流变阻尼器作为控制器来施加控制力,通过编制计算机程序进行仿真分析。研究表明,对层间隔震结构进行半主动控制是有效的,结构的隔震层相对位移和顶层位移反应大大降低,进行半主动控制可以达到与主动控制相接近的控制效果;隔震层阻尼、隔震度和隔震层位置对层间隔震结构的控制有明显影响。     

磁流变阻尼器对高层建筑风振反应的半主动控制

本文探讨了磁流变阻尼器在高层建筑风振控制中的应用，在经典线性最优控制理论的基础上，根据磁流变阻尼器的特点，提出了一种新型的半主动控制策略，应有该方法对一40层的钢结构的风振反应进行了计算机模拟，结果表明，采用磁流变阻尼器对高层建筑进行半主动控制的能够有效减小结构的风振反应。     

Simplified design method for shear-valve magnetorheological dampers

Based on the Bingham parallel-plate model, a simplified design method of shear-valve magnetorheological(MR) dampers is proposed considering the magnetic circuit optimization. Correspondingly, a new MR damper with a full-length effective damping path is proposed. The prototype dampers are also fabricated and studied numerically and experimentally. According to the test results, the Bingham parallel-plate model is further modified to obtain a damping force prediction model of the proposed MR dampers. This prediction model considers the magnetic saturation phenomenon. The study indicates that the proposed simplified design method is simple, effective and reliable. The maximum damping force of the proposed MR dampers with a full-length effective damping path is at least twice as large as those of conventional MR dampers. The dynamic range of damping force increases by at least 70%. The proposed damping force prediction model considers the magnetic saturation phenomenon and it can realize the actual characteristic of MR fluids. The model is able to predict the actual damping force of MR dampers precisely.     

Seismic response control of frame structures using magnetorheological/electrorheological dampers

Semi‐active control of buildings and structures for earthquake hazard mitigation represents a relatively new research area. Two optimal displacement control strategies for semi‐active control of seismic response of frame structures using magnetorheological (MR) dampers or electrorheological (ER) dampers are proposed in this study. The efficacy of these displacement control strategies is compared with the optimal force control strategy. The stiffness of brace system supporting the smart damper is also taken into consideration. An extensive parameter study is carried out to find the optimal parameters of MR or ER fluids, by which the maximum reduction of seismic response may be achieved, and to assess the effects of earthquake intensity and brace stiffness on damper performance. The work on example buildings showed that the installation of the smart dampers with proper parameters and proper control strategy could significantly reduce seismic responses of structures, and the performance of the smart damper is better than that of the common brace or the passive devices. The optimal parameters of the damper and the proper control strategy could be identified through a parameter study. Copyright © 2000 John Wiley & Sons, Ltd.     

Semi‐active fuzzy control for seismic response reduction using magnetorheological dampers

A semi‐active fuzzy control strategy for seismic response reduction using a magnetorheological (MR) damper is presented. When a control method based on fuzzy set theory for a structure with a MR damper is used for vibration reduction of a structure, it has an inherent robustness, and easiness to treat the uncertainties of input data from the ground motion and structural vibration sensors, and the ability to handle the non‐linear behavior of the structure because there is no longer the need for an exact mathematical model of the structure. For a clipped‐optimal control algorithm, the command voltage of a MR damper is set at either zero or the maximum level. However, a semi‐active fuzzy control system has benefit to produce the required voltage to be input to the damper so that a desirable damper force can be produced and thus decrease the control force to reduce the structural response. Moreover, the proposed control strategy is fail‐safe in that the bounded‐input, bounded‐output stability of the controlled structure is guaranteed. The results of the numerical simulations show that the proposed semi‐active control system consisting of a fuzzy controller and a MR damper can be beneficial in reducing seismic responses of structures. Copyright © 2004 John Wiley & Sons, Ltd.     

基于遗传算法的粘滞阻尼器减震结构优化设计研究

以线性粘滞阻尼器加固剪切型规则框架结构为研究对象,基于能量原理提出阻尼系数正比于层间位移(α+1)次方的分配方式,在此基础上提出了一种基于遗传算法的粘滞阻尼器减震结构优化设计方法.使得中震下结构最大层间位移角小于允许值,以满足"中震不坏"的设计目标,同时令附加总阻尼系数最小,满足经济性要求.以12层规则框架为例,分别采...     

基于经验遗传-单纯形算法和结构模态参数识别结构物理参数的方法

对于复杂的大自由度系统的反演分析,遗传算法每步计算中包含大量的正演分析,成为限制遗传算法应用的运行速度的瓶颈。减少反演分析中的正演计算次数,是扩大遗传算法适用范围的有效途径。经验遗传-单纯形算法正是解决这一问题的一种有效方法。本文将这一方法应用于不完全模态参数已知条件下的结构物理参数识别研究。结果表明:本文建议的方法有精度和搜索效率高、对初值选取依赖性不强、可以反映"残缺"的高阶模态信息等优点。     

基于遗传算法优化的高层建筑风振模糊控制

本文针对高层建筑风振控制问题,应用基于遗传算法优化模糊规则库的模糊控制方法,通过MR阻尼器实现减小高层建筑风振反应. 采用双输入、单输出的模糊控制策略, 即以风荷载和其变化率为输入量, 以MR阻尼器所提供的控制力为输出量.利用基于遗传算法的优化的模糊规则库,根据作用模糊子集的推理方法进行模糊推理运算, 并采用常用的重心法进行解模糊处理.以某12层框架结构为例, 进行数值模拟分析,并与优化前的模糊控制策略和LQR最优控制策略进行比较.数值分析结果表明,利用遗传算法使优化模糊规则库得以优化,改善了模糊控制的效果,有效地减小了结构的风振反应.     

Parameter identification for leaky aquifers using global optimization methods

In the past, graphical or computer methods were usually employed to determine the aquifer parameters of the observed data obtained from field pumping tests. Since we employed the computer methods to determine the aquifer parameters, an analytical aquifer model was required to estimate the predicted drawdown. Following this, the gradient‐type approach was used to solve the nonlinear least‐squares equations to obtain the aquifer parameters. This paper proposes a novel approach based on a drawdown model and a global optimization method of simulated annealing (SA) or a genetic algorithm (GA) to determine the best‐fit aquifer parameters for leaky aquifer systems. The aquifer parameters obtained from SA and the GA almost agree with those obtained from the extended Kalman filter and gradient‐type method. Moreover, all results indicate that the SA and GA are robust and yield consistent results when dealing with the parameter identification problems. Copyright © 2006 John Wiley & Sons, Ltd.     

MR阻尼器对桅杆结构风振响应的智能半主动控制

本文基于修正的拉格朗日坐标描述法，推导了空间四节点纤绳单元的大位移刚度矩阵的具体表达式。在将桅杆结构离散为空间四节点纤绳单元和梁单元的计算模型的基础上，建立了桅杆结构非线性风振响应分析的有限元方法。根据瞬时最优主动控制的原则，提出了MR阻尼器对桅杆结构风振反应智能半主动控制基于阻尼器位移的“开关—耗能”半主动控制策略。算例结果表明MR阻尼器能有效地减小桅杆结构的风振反应。     

Parameter identification of hysteretic model of rubber-bearing based on sequential nonlinear least-square estimation

In order to evaluate the nonlinear performance and the possible damage to rubber-bearings (RBs) during their normal operation or under strong earthquakes, a simplified Bouc-Wen model is used to describe the nonlinear hysteretic behavior of RBs in this paper, which has the advantages of being smooth-varying and physically motivated. Further, based on the results from experimental tests performed by using a particular type of RB (GZN110) under different excitation scenarios, including white noise and several earthquakes, a new system identification method, referred to as the sequential nonlinear least-square estimation (SNLSE), is introduced to identify the model parameters. It is shown that the proposed simplified Bouc-Wen model is capable of describing the nonlinear hysteretic behavior of RBs, and that the SNLSE approach is very effective in identifying the model parameters of RBs.