Preliminary Investigation of Magnetic Fluid Active Damper

对以下5个项目进行了调查。(1)磁流体主动阻尼器实验装置的搭建实验装置是为了测试在振荡容器（圆柱体）中，利用外加磁场的控制对浸入磁流体中的活塞运动的抑制作用。活塞通过弹簧-质量系统与气缸相连。筒体由激振器振荡，频率差= 2- 10hz。通过施加振荡磁场在磁流体中产生抑制力。当使用磁铁矿颗粒质量浓度为50%的煤油基磁流体时，系统的固有频率设计为5Hz。介绍了神经网络控制系统作为控制方法。(2)磁流体主动阻尼器的动态特性采用上述第(1)项所述的装置获得主动阻尼器的动态特性。设计了串联和并联型神经控制器（NC）来控制活塞振荡。试验结果表明，在小于固有频率f = 5Hz的低频范围内，并联数控比串联数控有较好的抑制活塞振荡的效果。采用含氮化铁颗粒的磁流体，与含磁铁矿颗粒的普通磁流体相比，获得了更高效的磁流体主动阻尼器特性。(3)磁流体主动阻尼器的理论研究通过理论研究了解了振动的抑制机理，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研究磁流体作动器的动态特性，对实验装置进行了细微的改变。振荡磁场在静止磁流体中引起的活塞运动。得到了活塞振荡运动的幅值作为频率和磁场强度的函数。(5)平板在磁流体中振荡的基本研究选择平板对作用在振荡体上的流体力进行简单分析。给出了粘性阻尼系数和附加质量系数的计算公式，并与实验结果进行了比较。结果表明，在含有氮化铁颗粒的被测磁流体中，由于外加磁场而作用在板上的流体阻力的增加速率比含有磁性颗粒的被测磁流体大。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