Preliminary Investigation of Magnetic Fluid Active Damper

(1)磁流体主动阻尼器实验装置的研制该实验装置是用来测试在外加磁场的控制下，振动容器(圆柱)中的活塞运动在磁性液体中的抑制情况。活塞通过弹簧-质量系统连接到气缸。气缸由激振器振荡，频率为OFF=2-10赫兹。通过施加振荡磁场，在磁性液体中产生抑制力。当使用质量浓度为50%的磁铁矿颗粒的煤油基磁流体时，系统的固有频率设计为5赫兹。(2)磁流体主动阻尼器的动态特性利用上述(1)所述的装置获得了主动阻尼器的动态特性。神经…设计了串联型和并联型多控制器(NC)来控制活塞振动。试验结果表明，在f=5 Hz的低频范围内，与串联式NC相比，采用并联式NC可以抑制该系统中活塞的振荡，并取得了较好的效果。磁流体主动阻尼器的理论研究对磁流体主动阻尼器的抑制机理进行了理论研究，得到了完全抑制活塞运动的必要条件。(4)磁流体作动器的频响曲线研究为了考察磁流体作动器的动态特性，对实验装置进行了微小的改变。在外加振荡磁场的作用下，静止磁性流体中的活塞运动。(5)平板在磁流体中振动的基础研究选用平板来简单地分析作用在振动体上的流体力。得到了粘性阻尼系数和附加质量系数的估计值，并与实验结果进行了比较。结果表明，在含有氮化铁颗粒的受试磁性液体中，由于外加磁场作用于平板上的流体阻力的增加速率大于含有磁性颗粒的磁性液体。较少

The investigations on the following 5 items are conducted.(1) Construction of an experimental apparatus for the magnetic fluid active damperThe experimental apparatus was constructed to test the suppression of a piston motion immersed in the magnetic fluid in an oscillating container (cylinder) by the control of the applied magnetic field. The piston is connected to the cylinder through a spring-mass system. The cylinder is oscillated by the exciter With frequency off = 2-10 Hz. The suppression force is induced in the magnetic fluid by applying oscillating magnetic field. The natural frequency of the system is designed to be 5Hz when the kerosene based magnetic fluid with 50% mass concentration of magnetite particles is used. As the controlling method, the neural-network controller system is introduced.(2) Dynamic characteristics of the magnetic fluid active damperThe dynamic characteristics of the active damper are obtained by using the apparatus explained in the above item (1). Neuro … More -controllers (NC) of series and parallel types are designed to control the piston oscillation. The test results show that it is possible to suppress the oscillation of the piston in this system and to give relatively good results by using the parallel type NC compared to the series type NC in the range of the low frequency smaller than the natural frequency of f = 5Hz. By using the magnetic fluid with iron-nitride particles, more efficient characteristics of the magnetic fluid active damper is obtained in comparison with the usual magnetic fluid with the magnetite particles.(3) Theoretical study of the magnetic fluid active damperThe theoretical study is conducted to understand the suppression mechanism of the oscillation and the necessary conditions of the complete suppression of the piston motion is obtained.(4) Study of frequency response curve as a magentic fluid actuatorTo investigate the dynamic characteristics of the magnetic fluid actuator, the experimental appatatus was slightly changed. The piston motion induced in the stationary magnetic fluid by the applying oscillating magnetic field. The amplitude of the oscillating motion of the piston is obtained as a function of the frequency and the magentic field strength.(5) Basic study of the oscillation of a flat plate in the magnetic fluidThe flat plate was selected to analyze simply the fluid force acting on the oscillating body. The evaluation of the viscous damping factor and the added mass coefficient was obtained and compared with the experimental results. It is clarified that an increasing rate of a fluid resistance acting on the plate due to the applied magnetic field is large in the tested magnetic fluid with the iron-nitride particles compared to the one with the magnetic particles. Less