共查询到20条相似文献，搜索用时 15 毫秒
1.
Theoretical research on aggregative dynamic pressure damper 总被引：1，自引：0，他引：1
To broaden the frequency width and increase the damping coefficient of a dynamic pressure damper, we designed an aggregative dynamic pressure damper （ADPD）. Combined with the advantages of traditional dynamic pressure dampers （TDPD）, ADPD can not only increase the damping coefficient in wide frequency range for valve control system, but also absorb partial pressure pulsations and impacts in the low and high frequency fields. Based on the theoretical research and the analysis compared with TDPD, we concluded that the ADPD was superior to the TDPD in the middle high frequency field, and the main parameters influencing the performance of the damper were the damping stiffness, orifice flow coefficient, pre-charge pressure, and the volume of the damper accumulator. 相似文献
2.
祝长生 《浙江大学学报(A卷英文版)》2003,4(5)
A disc-type magneto-rheological fluid damper operating in shear mode is proposed in this paper, which is based on the special characteristics of the magneto-rheological (MR) fluid with rapid, reversible and dramatic change in its rheological properties by the application of an external magnetic field. The magnetic field of the disc-type MR fluid damper is analysed by the finite element method; the controllability of the disc-type MR fluid damper on the dynamic behaviour of a rotor system; and the effectiveness of the disc-type MR fluid damper in controlling the vibration of a rotor system, are studied in a flexible rotor system with an over-hung disc. It is shown that the magnetic flux density of the disc-type MR fluid damper in the working areas can significantly change with the applied current in the coil; and that the dynamic behavior of the disc-type MR fluid damper can be varied by the application of an external magnetic field produced by a low voltage electromagnetic coil. The disc-type MR fluid damper can significantly change the dynamic characteristics of a rotor system, provided that the location of the disk-type MR fluid damper is carefully chosen. The disc-type MR fluid damper is a new actuator with good dynamic characteristics for rotating machinery. 相似文献
3.
INTRODUCTIONElectro rheological (ER ) Magneto rheologi cal(MR)fluidisakindofcontrollablefluidwhoserheologicalproperties,especiallyapparentviscosity,canbedramaticallyandreversiblyvariedinafewmillisecondsbytheapplicationofanexternalelectrical magneticfield… 相似文献
4.
Zhu Chang-sheng 《浙江大学学报(A卷英文版)》2003,4(5):514-519
A disc-type magneto-rheological fluid damper operating in shear mode is proposed in this paper, which is based on the special
characteristics of the magneto-rheological (MR) fluid with rapid, reversible and dramatic change in its rheological properties
by the application of an external magnetic field. The magnetic field of the disc-type MR fluid damper is analysed by the finite
element method; the controllability of the disc-type MR fluid damper on the dynamic behaviour of a rotor system; and the effectiveness
of the disc-type MR fluid damper in controlling the vibration of a rotor system, are studied in a flexible rotor system with
an overhung disc. it is shown that the magnetic flux density of the disc-type MR fluid damper in the working areas can significantly
change with the applied current in the coil; and that the dynamic behavior of the disc-type MR fluid damper can be varied
by the application of an external magnetic field produced by a low voltage electromagnetic coil. The disc-type MR fluid damper
can significantly change the dynamic characteristics of a rotor system, provided that the location of the disk-type MR fluid
damper is carefully chosen. The disc-type MR fluid damper is a new actuator with good dynamic characteristics for rotating
machinery.
Project supported partially by the EC BRITE/EURAM program under BRPR-CT97-0544 IMPACT project and State Key Laboratory of
Vibration, Shock and Noise, Shanghai Jiatong University 相似文献
5.
对交流电机转子横振时电磁阻尼及考虑电磁阻尼时转子横振进行了研究.首先应用磁场理论求得了电机三相不对称运行时电磁阻尼力,并对三相对称时的电磁阻尼进行了计算.接着用拉格朗日-麦克斯韦方程求得了转子横向振动的方程,画出了三相对称时转子强迫振动的幅频曲线,并与实验进行了对照,实验结果与理论结果吻合的很好. 相似文献
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8.
用于被动力/力矩再现的新型磁流变液阻尼器 总被引：1，自引：0，他引：1
研制了一种用于被动力/力矩再现的新型磁流变液阻尼器,该阻尼器能够在磁场的作用下产生连续变化的阻尼力/力矩.阻尼器的结构包括一个上盖和一个下盖,一个转子设置于上盖和下盖之间,转子与上下盖之间的间隙充满磁流变液,在磁场作用下其粘度变大时,转子相对于壳体将受阻尼力作用.阻尼力矩的模型主要由以下几部分组成:一是由磁场作用于磁流变液产生的力矩,二是由磁流变液的动力粘度产生的力矩,最后是由装置的摩擦产生的力矩.由动力粘度产生的力矩可以通过简单的方法进行计算,由摩擦产生的力矩可以通过实验测得,而由磁场产生的力矩则要通过电磁场的有限元分析得到.最后,对研制的阻尼器原型进行了性能实验,检验了设计方法的有效性. 相似文献
9.
JIANG Jiandong LIANG Xichang ZHANG Bo XIAO Junli State Key Laboratory of Mechanical Transmissions Chongqing University Chongqing P.R. China 《重庆大学学报(英文版)》2004,3(1):11-15
1.IntroductionOneofthemostimportantperformanceparameterofautomobilesisthecushioningability.Soallkindsofvibrationdampersareassembledinvehicles,amongwhichthefullest-blownoneisthehydraulicdamperworkingthroughreciprocatingmovementofhinderedpistoninahydrauliccylinderabsorbingvibrationwithself-containedspring.Butsuchkindofdampercannotchangewiththechangeincharacteristicsofavibrationsource(suchasamplitudeofvibrationandphase),lackingofenoughself-adaptingability.Magnetorheologicaldamperfluid(MRF)isaty… 相似文献
10.
Because brushless direct current (BLDC) motors have the advantages of a compact size, high power density, high efficiency, and long operating life time, they are widely used in many industrial products and electric traction systems. It is known that the BLDC motors have no brushes for commutation. They are commutated with electronically commutation. So, the rotor position information of the BLDC motors must be known to understand which winding will be energized according to the energizing sequence. In most of the existing BLDC motor drivers, rotor position information is detected by Hall effect sensors. This kind of mechanical position sensors will bring additional connections and costs, reliability decrease and noise increase. In order to improve the control performance and extend the range of speed regulation for BLDC motors, a position sensorless control method is proposed in this paper. In the proposed control method, rotor position information of the BLDC motors is detected from the back electromagnetic forces (back-EMFs) which are estimated by an unknown-input observer with line to line currents and line to line voltages. For the purpose of verifying the effectiveness of the proposed control method, a model is built and simulated on the Matlab/Simulink platform. The simulation results show that the speed regulation performance of BLDC motors is improved compared with using Hall effect sensors. At the same time, the reliability of the BLDC motors is improved and the costs of them are reduced because the position sensor is eliminated. 相似文献
11.
为了研究橡胶浮置板轨道对城市高架箱梁结构的减振特性,建立了高架橡胶浮置板轨道结构三雏有限元模型,分析了当减振器刚度和轨道板长度变化对高架桥系统动力响应影响。研究结果表明。减振器刚度的改变对浮置板前10阶振动频率分布影响较大,对累积质量分数分布特性几乎没有影响,相同阶数条件下浮置板的振动主频随减振器刚度减小而减小;列车通过时浮置板轨道以增大自身的振动来达到减小对桥梁结构振动能量输入的目的,在减振频率范围内,浮置板的减振效果随减振器刚度增大而减小,随浮置板长度的减小而减小。 相似文献
12.
设计了应用TiNi形状记忆合金环作耗能元件的被动减振装置,并对装置的力学和减振性能进行了初步评价.对加载和卸载过程中力-位移曲线进行了研究,当不对环水平方向的变形进行约束时,力-位移曲线为近似于直线且接近重合的2条曲线;若应用滑块对环水平方向的变形进行约束,在力-位移曲线上能形成滞回环,且随位移增加变得更饱满.滞回环的加载和卸载部分不与横坐标平行,而是2条斜线,装置受力时的这种变形特点,可提高装置的抗过载能力.增加环的数量,在相同位移时装置的耗能量明显增加. 相似文献
13.
Dynamic response analysis of damper connected adjacent multi-story structures with uncertain parameters is carried out. A formula of the multi degree of freedom （MDOF） for the structure-damper system with stochastic parameters is derived. The uncertainties of mass and stiffness are taken into consideration firstly. The ground acceleration is represented by Kanai-Tajimi filtered non-stationary process. The mean square random responses of structural displacement and story drift are chosen as the optimization objective. The variations of mean square responses of top floor displacements and bottom story drifts in neighboring structures with the damper stiffness and damping coefficient are analyzed in detail. Through the parametric study, the acquiring optimum parameters of damper are regarded as numerical results. Then, a reducing order model of the MDOF system for adjacent structures with mean parameters is presented. The explicit expressions for determining optimal parameters of Kelvin model-defined damper which is used to connect adjacent single degree of freedom （SDOF） structures subjected to a white-noise excitation are employed to achieve the appropriate damper parameters, which are called theory results. Through a comparative study, it can be found that the theory values of damper parameters are consistent with the results based on extensive parametric studies. The analytical results can be obtained by using the first natural frequencies and the total mass of the adjacent deterministic structures with mean parameters. The analytical formulas can be used to find appropriate parameters of damper between adjacent structures for engineering applications. The performance of damper is investigated on the basis of mitigations of mean square random responses of inter-story drifts, displacements and accelerations in adjacent structures. The numerical results demonstrate the robustness of coupled building control strategies. 相似文献
14.
介绍了水轮机组发电机转子在转动过程中的三种偏心:静偏心、振动偏心和转动偏心,建立了转子在不平衡电磁力作用下的非线性振动微分方程。采用数值方法分析了转动偏心和静偏心对轴系电磁振动特性的影响,结果表明,这两种偏心与电磁力呈非线性关系,随着偏心的增大使不平衡磁拉力作用不断加强,机组的横向振动固有频率有所降低,转子和转轮的振幅不断增大,倍频共振时的振幅也显著加大,转子系统展现出非常复杂的非线性动力学特征。 相似文献
15.
发电机组轴系弯扭耦合电磁激发振动数学模型 总被引：1，自引：0，他引：1
依据机电分析动力学理论 ,找到了发电机组定转子间气隙磁场的能量 ,得到了作用在发电机转子上的电磁力 (矩 ) ,建立了一个基于分段连续质量的发电机组轴系弯扭耦合电磁激发振动的数学模型 .该模型考虑了不平衡、陀螺力矩、转动惯量、剪切变形及阻尼的影响 ,是一个比较精确的模型 .对全面探索发电机组的振动规律具有应用价值 相似文献
16.
Optimal arrangement of viscoelastic dampers for seismic control of adjacent shear-type structures 总被引：1，自引：0，他引：1
The optimal arrangement of viscoelastic dampers (VEDs) used to link two adjacent shear-type structures under seismic excitation was investigated. A two-step optimal design method is proposed. First, optimal parameter expressions of the Kelvin model are used to calculate the optimal stiffness and damping coefficient of the VEDs. Then, using the two-step optimal design method, taking the quadratic performance index as the optimization objective, the optimal arrangement of the dampers is determined. General rules about the optimal arrangement of the VEDs were obtained. The results show that the placement of only one damper between two adjacent shear-type structures should be avoided; if more than one damper is used, they should be distributed on the top and lower floors of the structures. Optimization of the number of dampers had little effect on response reduction. The most important factor was the optimization of the placement of the dampers. Through comparative study, for buildings of equal and unequal heights, the optimal parameters of dampers from parametric studies were shown to match the theoretical results for different numbers and placements of dampers. The level of response reduction was shown to be sensitive to the damping coefficient of the dampers. 相似文献
17.
针对振动压路机采用的橡胶减振装置存在阻尼不可调的问题,文章利用磁流变液具有快速相变和易于控制的特征,并结合压路机结构特性设计一种由磁流变和橡胶耦合而成的变阻尼减振器,通过力学计算与有限元仿真,对减振器结构设计进行校核与优化。仿真结果发现:经过结构优化的变阻尼减振器提高了控制磁场的利用率,从而提高磁流变橡胶耦合减振器的性能与品质。 相似文献
18.
INTRODUCTIONRoadvehiclesuspensiondesignhasreceivedgreatattentioninrecentyears .Theperformanceofthesuspensionsystemplaysanimportantroleinachievinggoodhandlingandridingcomfort.Practically ,thesimplestandmostcommontypesofsuspensionsarepassiveinthesensethatno… 相似文献
19.
A new kind of fuzzy control scheme, based on the identification of the signal's main frequency and the behavior of the ER
damper, is proposed to control the semi-active suspension system. This method adjusts the fuzzy controller to achieve the
best isolation effect by analyzing the main frequency's characters and inspecting the change of system parameters. The input
of the fuzzy controller is the main frequency and the optimal damping ratio is the output. Simulation results indicated that
the proposed control method is very effective in isolating the vibration.
Project (No. 69974024) supported by the National Natural Science Foundation of China 相似文献
20.
Xu-dong Zheng Zhong-he Jin Yue-lin Wang Wei-jun Lin Xiao-qi Zhou 《浙江大学学报(A卷英文版)》2009,10(10):1413-1420
We present a bulk micromachined in-plane capacitive accelerometer fabricated with an improved process flow, by etching only one-fifth of the wafer thickness at the back of the silicon while forming the bar-structure electrode for the sensing capacitor. The improved flow greatly lowers the footing effect during deep reactive ion etching （DRIE）, and increases the proof mass by 54% compared to the traditional way, resulting in both improved device quality and a higher yield rate. Acceleration in the X direction is sensed capacitively by varying the overlapped area of a differential capacitor pair, which eliminates the nonlinear behavior by fixing the parallel-plate gap. The damping coefficient of the sensing motion is low due to the slide-film damping. A large proof mass is made using DRIE, which also ensures that dimensions of the spring beams in the Y and Z directions can be made large to lower cross axis coupling and increase the pull-in voltage. The theoretical Brownian noise floor is 0.47 μg/Hz^1/2 at room temperature and atmospheric pressure. The tested frequency response of a prototype complies with the low damping design scheme. Output data for input acceleration from -1 g to 1 g are recorded by a digital multimeter and show very good linearity. The tested random bias of the prototype is 130 μg at an averaging time of around 6 s. 相似文献