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1.
结构振动的滑模变结构半主动控制   总被引:1,自引:0,他引:1  
研究应用磁流变阻尼器(MRD)对结构振动半主动控制的算法和原理。研制并对磁流变阻尼器进行了阻尼特性实验,采用非线性滞回双粘性模型描述磁流变阻尼器的阻尼特性,模型结果与实验结果非常一致。采用滑模控制算法和趋近律方法设计了半主动控制器。利用滑模控制方法所建立的控制器,本文给出了地震激励下结构振动半主动控制算例。计算分析表明,半主动滑模控制具有控制效果明显、鲁棒性好等优点,是一种非常有发展前途的控制方法。  相似文献   

2.
由于磁流变阻尼器是一种高度非线性的装置,因此建立与之相适应的控制系统是半主动控制问题的关键。本文采用改进的Bingham模型建立了磁流变阻尼器的动力学特性模型,根据天棚阻尼开关控制、天棚阻尼连续控制和模糊控制三种控制方法,确立了从系统速度响应到磁流变阻尼器励磁电流之间的关系,并开发了一套半主动控制系统。在一个两自由度的简化车辆试验平台上进行半主动控制试验,对比研究了三种控制方法的控制效果。实验结果表明,在1.3Hz~2.0Hz的低频段内,开关控制的最佳减振效果为15.1%,连续控制的最佳减振效果为14.9%,模糊控制的最佳减振效果为20.1%。可见,三种控制方法都能有效的减小车体的振动,模糊控制的减振效果最佳。  相似文献   

3.
针对水平和竖向地震作用下高层建筑结构的混合振动控制问题,研究调谐质量阻尼器(tuned mass damper, TMD)体系、隔震结构体系、隔震与TMD混合控制体系3种策略对水平与竖向地震共同作用下结构振动响应的减振效果。选取典型的20层钢结构Benchmark结构模型,利用ANSYS软件建立带有TMD和隔震层结构的有限元模型,比较了结构在水平地震单独作用下与水平和竖向地震共同作用下的振动响应。结果表明,水平方向上的振动响应无明显变化;竖直方向上,有控状态下的减振指标相对于无控状态出现了增大现象,尤其是层间隔震结构增大较为明显。研究成果可为高烈度区高层隔震结构设计提供参考。  相似文献   

4.
时滞对结构振动半主动控制效果的影响   总被引:5,自引:0,他引:5  
应用磁流变阻尼器对结构振动进行控制,采用最优控制原理设计了控制器,给出在地震激励下结构半主动控制的仿真计算。研究了时滞对结构振动半主动控制效果的影响。数值结果表明:本文设计的半主动控制策略可有效地减小结构的振动响应,时滞对磁流变半主动控制效果随着时滞的增大而变差,但时滞不会导致该反馈控制系统的失稳。  相似文献   

5.
为了改善滑移隔震结构的减震效果和适用范围,提出3种磁流变阻尼器(MRD)与滑移隔震混合方案,建立了MRD与滑移隔震混合控制结构的动力分析模型,对6层MRD与滑移隔震混合控制结构进行地震反应分析。MRD与滑移隔震混合结构的3种混合方案的相对加速度峰值、相对速度峰值、相对位移峰值和层间剪力峰值分别比滑移隔震结构有不同程度的降低,而混合方案3的控制效果更加明显。在此基础上,建立了MRD与滑移隔震混合结构优化设计模型,采用IHGA程序对结构进行优化设计。结果表明,MRD与滑移隔震混合结构的各项地震反应均得到了更好地控制。  相似文献   

6.
磁流体特性对磁流变火炮后坐阻尼器性能的影响   总被引:3,自引:0,他引:3  
侯保林 《爆炸与冲击》2006,26(3):245-249
针对火炮后坐磁流变阻尼器的特点,以某单管25 mm火炮实验用磁流变阻尼器为研究对象,基于Herschel-Bulkley本构模型,建立了该炮磁流变后坐阻尼器的轴对称一维层流模型,获得了不同磁场作用下阻尼力随活塞速度的变化规律。运用火炮的后坐运动方程,计算了不同磁流体特性指数下,火炮的后坐位移和后坐速度。计算结果表明,磁流体特性指数的变化对磁流变后坐阻尼器的性能影响显著。  相似文献   

7.
以提高磁流变液阻尼器控制性能为目的,分析了活塞式磁流变液阻尼器结构特点,并提出了端部阻尼器结构;通过实验研究明确了磁流变液流经圆形截面和矩形截面的力学特性,总结了磁流变液流经不同类型和尺寸的小孔的粘性阻尼力特性和磁场作用时的磁场效应,并得出了提高端部阻尼器控制性能的方法和措施。设计出控制性能较好的矩形截面孔的端部控制磁流变液阻尼器。给出阻尼器最大阻尼力和可控比与线圈磁场强度关系。  相似文献   

8.
内通道式磁流变阻尼器研究   总被引:2,自引:1,他引:1  
设计制作了一种新型的内通道式磁流变液阻尼器,该阻尼器的流场通道位于线圈内部,磁流变效应发生在两层固定的平板区域之间,并能保持磁流变液的流向与磁感应方向垂直,即保证磁流变液的大面积成链,产生大的可控阻尼力,又具备失效安全性;根据宾汉模型,建立了阻尼器的准静态力学模型;最后对研制的阻尼器进行动力学实验研究,并与理论结果进行比较,二者吻合较好。  相似文献   

9.
一种改进的磁流变阻尼器模型及其对振动主动控制的应用   总被引:1,自引:0,他引:1  
本文对一个带有磁流变阻尼器的二自由度弹簧阻尼系统的基础激励响应进行了主动控制数值仿真.使用改进的P-模型模拟磁流变阻尼器的力学性能,应用H2/LQG方法设计了状态反馈增益矩阵,选用Clipped-Optimal控制律完成磁流变阻尼器控制电流的确定.仿真结果表明受控系统的响应水平显著小于无控系统,改进的P-模型运作良好,可以在数值仿真过程中代替真实磁流变阻尼器的工作.  相似文献   

10.
通过对磁流变阻尼器sigmoid模型进行数值计算分析,揭示了各参数对该模型阻尼力的影响,证明了通过合理有效地选择参数可设计出符合工程实际应用的磁流变阻尼器.对确定性激励下磁流变阻尼器的Sigmoid模型进行了理论分析.指出了采用非线性的阻尼器模型能更精确地描述汽车悬架的振动特性.从而证明了磁流变阻尼器有良好的使用价值和Sigmoid模型磁流变阻尼器在汽车控制工程应用中的可行性.  相似文献   

11.
The last decade has witnessed an important role of magneto-rheological dampers in the semi-active vibration control on the basis of empirical models. Those models established by fitting experimental data, however, do not offer any explicit expressions for the stiffness and the damping of magneto-rheological dampers. Hence, it is not easy for engineers to get any intuitive information about the effects of stiffness and damping of a magneto-rheological damper on the dynamic performance of a controlled system. To manifest the nonlinear properties of a magneto-rheological damper, this paper presents the hysteretic phenomena and the additional nonlinear stiffness of a typical magneto-rheological damper in terms of equivalent linear stiffness and equivalent linear damping. Then, it gives a brief discussion about the effect of nonlinear stiffness on the vibration control through the numerical simulations and an experiment for the semi-active suspension of a quarter car model with a magneto-rheological damper installed. Both numerical simulations and experimental results show that the additional nonlinear stiffness in the magneto-rheological damper is remarkable, and should be taken into consideration in the design of vibration control.  相似文献   

12.
A NEW STOCHASTIC OPTIMAL CONTROL STRATEGY FOR HYSTERETIC MR DAMPERS   总被引:3,自引:0,他引:3  
I. INTRODUCTION Magneto-rheological (MR) ?uid as a smart material possesses fairly good essential characteristics suchas reversible change between liquid and semi-solid in milliseconds with a controllable yield strengthwhen exposed to a magnetic ?eld. A…  相似文献   

13.
考虑拉索垂度及抗弯刚度的影响,得出了索-阻尼器系统振动偏微分方程;用中心差分法将偏微分方程在空间内离散,导出了系统的面内振动常微分方程组;提出了使用MR阻尼器(Magnetorheological Damper)作为控制设备,模糊集为基础的半主动控制算法,并运用提出的算法对索-阻尼器系统进行了振动控制分析。本文方法的优势在于算法自身的鲁棒性、处理非线性问题的能力强和不需要结构的精确数学模型,算法需要的输入变量少,可以解决实际工程中斜拉索的振动响应信息难以测量的困难。模糊算法的输出直接控制MR阻尼器的输入电压。与LQR-Clipped算法不同,MR阻尼器的输入电压可以是零与最大值之间的任意值。本文以实际斜拉桥拉索为例,分析了拉索的振动控制效果,结果表明本文提出的模糊半主动控制算法,使MR阻尼器的功能得到了更好的发挥,比MR被动控制效果好,且可以减小控制力。  相似文献   

14.
Most of the currently employed vibration-based identification approaches for structural damage detection are based on eigenvalues and/or eigenvectors extracted from dynamic response measurements, and strictly speaking, are only suitable for linear system. However, the inception and growth of damage in engineering structures under severe dynamic loadings are typical nonlinear procedures. Consequently, it is crucial to develop general structural restoring force and excitation identification approaches for nonlinear dynamic systems because the restoring force rather than equivalent stiffness can act as a direct indicator of the extent of the nonlinearity and be used to quantitatively evaluate the absorbed energy during vibration, and the dynamic loading is an important factor for structural remaining life forecast. In this study, based on the instantaneous state vectors and partially unknown excitation, a power series polynomial model (PSPM) was utilized to model the nonlinear restoring force (NRF) of a chain-like nonlinear multi-degree-of-freedom (MDOF) structure. To improve the efficiency and accuracy of the proposed approach, an iterative approach, namely weighted adaptive iterative least-squares estimation with incomplete measured excitations (WAILSE-IME), where a weight coefficient and a learning coefficient were involved, was proposed to identify the restoring force of the structure as well as the unknown dynamic loadings simultaneously. The response measurements of the structure, i.e., the acceleration, velocity, and displacement, and partially known excitations were utilized for identification. The feasibility and robustness of the proposed approach was verified by numerical simulation with a 4 degree-of-freedom (DOF) numerical model incorporating a nonlinear structural member, and by experimental measurements with a four-story frame model equipped with two magneto-rheological (MR) dampers mimicking nonlinear behavior. The results show the proposed approach by combining the PSPM and WAILSE-IME algorithm is capable of effectively representing and identifying the NRF of the chain-like MDOF nonlinear system with partially unknown external excitations, and provide a potential way for damage prognosis and condition evaluation of engineering structures under dynamic loadings which should be regarded as a nonlinear system.  相似文献   

15.
One of the present barriers to the realization of structural health monitoring is the lack of efficient and general identification methodologies for dealing with nonlinearity, because a priori knowledge of the nature and mathematical form of the nonlinearities of typical engineering structures are usually unknown. The studies on the identification of restoring force, which can be considered as a direct indicator of the extent of the nonlinearity, have received increasing attention in recent years. In this paper, the nonlinear restoring force (NRF) was estimated by using a power series polynomial, and each coefficient of the polynomial was identified by means of standard least-square techniques. No information about the system was needed, and only the applied excitations and the corresponding response time series were used for the identification. Two different cases, in which the system was under complete and incomplete excitations, were investigated. Moreover, the effect of noise level was also taken into consideration. The feasibility and robustness of the proposed approach were verified via a 2-degree-of-freedom (DOF) lumped-mass numerical model, and experimental tests on a 4-story shear building with magneto-rheological (MR) dampers which served to simulate nonlinear behavior. The results show that the proposed data-based method is capable of identifying the NRF in a chain-like multi-degree-of-freedom engineering structures without any assumptions on the structural parameters, and provides a promising way for damage detection in the presence of structural nonlinearities.  相似文献   

16.
The purpose of this study is to investigate analytically a single-degree-of-freedom (SDOF) building structure equipped with a friction damper for assessing its vibration control effect. Friction dampers are installed between stories to reduce inter-story displacements of building structures subjected to external loading. They are in general regarded to generate damping forces characterized by Coulomb damping, of which the directions are opposite to the inter-story velocities of building structures. Hence, the building structure model with friction dampers can be represented by a mass-spring-viscous-Coulomb damping system. The building response reduction as a result of damper installation can be provided by observing the damping ratio rather than the friction force contributed by the dampers. Since a large friction damper force is required to attenuate the response of the building due to strong excitation, friction force ratio is directly related to building response reduction, which is the friction force of the damper versus external force. Therefore, damping and friction force ratios are key parameters, playing a main role in selecting an optimal friction damper, which satisfies target response reduction. This study first identifies an SDOF building structure installed with a friction damper for free vibration with initial conditions. A?closed-form expression of normalized displacement is derived in terms of friction force ratio in the time domain. Peak and valley of displacements are also found and then the time when the structure stops is derived with recursive interval number. This study is extended to identify steady-state vibration of the structure by deriving closed-form solution in case of resonance in terms of friction force ratio. Then, the dissipated energy balance is identified for both free and steady-state vibrations. Finally, equivalent viscous damping ratios are derived by using friction force ratio based on dissipated energy balance equation. The derived equations in terms of viscous damping ratio and friction force ratio can provide insight to design a friction damper for reducing structural displacement under external loadings.  相似文献   

17.
MR阻尼器的半主动控制研究   总被引:3,自引:0,他引:3  
任晓崧  凌海梅 《力学季刊》2001,22(4):471-476
MR阻尼器能提供可以调节的阻尼力,适合用作减少结构地震响应的半主动控制器。本文对MR阻尼器的半主动控制进行研究,提出了状态跳跃算法,根据结构响应的大小实现MR阻尼器的状态切换,使结构响应得到有效的控制。这种控制策略简便,不需要在线计算,便于实施。由于速度响应直接影响MR阻尼器的阻尼力,建议用速度响应作为MR阻尼器进行状态切换的变量。文中给出了两个算例,进行了计算分析和比较,说明了状态跳跃控制算法的特点。  相似文献   

18.
论文通过三维空间有限元数值计算模型研究大型上翻式拱形钢闸门的流固耦合动力特性,取得闸门结构流固耦合条件下的振动模态参数,为闸门结构共振分析和采取合理的控振措施提供了科学依据.此外对控制结构强度和刚度的门顶溢流工况进行了闸门位移和应力分布分析,指出了存在问题和修改方向.论文成果可供类似工程设计时参考.  相似文献   

19.
电流变阻尼器动力特性的研究   总被引:6,自引:0,他引:6  
电流变液是一种可控流体,它在电场的作用下可从牛顿流体变为屈服剪应力较高的粘塑性体,且这种变化连续,可逆,迅速。本文在简要介绍了电流变阻尼器的原理和特点后,就电流变阻尼器的动力特性,如流量和阻尼力等,建立模型,将流体流动分为剪切流动和压差流动两种情况进行了讨论,并进行迭加,使流量和阻尼计算公式得到修正和完善,最后对阻尼力进行简化,提出压差流动占绝对优势,完全可以反映电流变阻尼器的阻尼特性,为进一步实现对阻尼器的控制提供了理论基础。  相似文献   

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