Research On Three-directional Vibration Control Of Sensitive Components

Environmental vibration of communication equipment is an important factor affecting the normal operation of vibration-sensitive components.Due to the complex working environment,wide distribution range of communication equipment,and wide vibration band and amplitude,the vibration control is very difficult.A number of measures have been proposed at home and abroad for environmental vibration,including various active and passive vibration isolation schemes,and horizontal and vertical vibration isolation schemes.However,the design of three-directional vibration isolation platform for wide-band and large-displacement environment vibrations is still incomplete and lacks systematic theoretical guidance.Therefore,this thesis combines the horizontal rolling isolation platform and vertical two-stage vibration isolation platform to perform systematic theoretical and experimental research on the high-performance threedirectional isolation platform.The impact of environmental vibration is reduced by three-directional vibration control to ensure the normal operation of vibration-sensitive devices in communication equipment.The investigations are as follows:(1)The dynamic model of the rolling vibration isolation platform is established,and the three-segment curve contour of the concave plate is proposed.The inherent characteristics of the vibration isolation platform and the effect of vibration reduction are analyzed through simulation.The relationship between the straight segment of the concave plate and the upper load is studied,and the design equation of the maximum absolute acceleration response of the load is deduced.The influence of the three parameters of inclination angle,frictional damping and maximum ground acceleration on the absolute acceleration response and maximum displacement response of the load are analyzed.The vibration isolation performance is verified by experiments.Experiment shows that the horizontal resonance frequency of this platform is between 0.5-1Hz,and it also has good vibration isolation effect for random excitation and periodical excitation.(2)For the bellow isolator,the mechanical properties of the two-parameter and three-parameter models are analyzed,and a design method for the optimal-damping ratio of the three-parameter model is proposed.Based on the theory,a two-parameter and three-parameter isolator model is given,and the vibration isolation performance of the isolator is experimentally tested.Two-parameter and three-parameter vibration isolators provide a model basis for the study of vertical vibration isolation platform.(3)A vertical two-stage vibration isolation platform model is proposed.One stage is a low-frequency,large-stroke fluid isolator,and the second stage is a small-stroke isolation platform.A seven-degree of freedom dynamic model is established for the secondary passive vibration isolation platform,which is composed by three-parameter fluid-damping vibration isolators.The influence of misalignment of mass-center on the vibration isolation effect is studied,which provides guidance for the layout of the vibration isolation platform.Based on the two-parameter bellows isolators,the voice coil motor is used for active control.The active control force of the voice coil motor is analyzed,and the stability condition of the feedback control system is deduced.Dynamic model of the secondary active-passive vibration isolation platform is established.Simulation result shows that active control can significantly suppress the resonant peak of passive isolation.A low-frequency and large-stroke oil isolator is built on the basis of a secondary small-stroke isolation platform,and the dynamic model of the whole vibration isolation system formed by the combination of the first-stage oil isolators and the two two-stage vibration isolation platforms is performed respectively.The transfer function of the whole vibration isolation platform is deduced.Simulation shows the integrated vibration isolation system of the primary and second combination has the characteristics of free-resonance and low-pass filter,which cannot be realized by a single isolator.At the same time,the active control of the secondary vibration isolation platform can effectively improve the influence of the resonance zone and further improve the vibration isolation effect.(4)A three-directional vibration isolation platform is built to conduct horizontal vibration isolation and vertical vibration isolation experiments respectively,and the horizontal and vertical vibration transmission characteristics and control effects of the vibration isolation platform is obtained.Under the random excitation of 1~200Hz,the transmission rate of primary,secondary and two-stage rolling vibration isolation platforms are all below 0dB.The main-horizontal excitation has little effect on the subhorizontal and vertical coupling vibrations.Under the excitation of seismic wave,the secondary rolling vibration isolation platform has a good passive vibration isolation effect,and the experimental and theoretical results are consistent.Under the vertical sweep excitation of 2~200Hz,the transmission rates of the two vertical two-stage vibration isolation platforms in the low frequency band are all less than 1,and they have good attenuation effect in the high frequency range.The measured curves agree well with the trend of the transmission rate calculated by theoretical model,which indicates that the theoretical model of the vertical two-stage vibration isolation platform is correct.