The Study For Floating Raft Vibration Isolator’s Expriment And Antiresonant Vibration Isolation Level’s Control

Vibration isolation and noise reduction is a problem has been widely concernedin the field of academic research and engineering application. The demand forvibration isolation becomes more popular. Traditional linear damped systems havegood performance on high-frequency vibration isolation. However, whenencountering low-frequency vibration the linear attenuation method cannot performwell. In recent years, some new types of low-frequency vibration isolation theory anddevice have been developed such as quasi-zero-stiffness, dynamic vibration absorber,inertia coupling antisonance vibration isolation and fluid floating raft antiresonancevibration isolator.In this paper, the theoretical vibration isolation characteristics of the fluidfloating raft was studied and a single-deck floating raft vibration isolator with a liquidlevel controller were developed based on anti-resonance mechanism. Force’stransmissibility of the raft at various liquid levels and gaps was measured byexperiments which verified antiresonance theory of the floating raft. With thecomparison of the discrepancy between experimental antiresonance data points andthe theoretical analysis at each gaps and the analysis of different gaps’ influence onthat discrepancy by combining the theorefical results, it further demonstrates thevalidity of the theoretical model under the condition of hypothesis. The advantagesand limitations of the methods of the tuning gap scheme and the tuning liquid levelscheme were discussed and a combination of the both schemes was suggested for theimprovement of vibration isolation in terms of lower force transmissibility and widerisolation bandwidth.In actual working conditions, the vibration frequency is always changing and thefloating raft at each liquid level can reduce each frequency vibriation. The optimalvibration attenuation (antisonance) related to liquid level-frequency curve and Force’stransmissibility-frequency curve is obtained by carrying out a large number ofexperiments. The control program is programmed with LabVIEW graphic languagebased on the optimal vibration attenuation liquid level curve and liquid levelcontroller and signal processor NI PXI-1602e, sensors and other instruments.Vibration signal was collected by force sensor; the frequency of vibration was gottenwith NI PXI-1602e instrument amplifying and filtering; the liquid level controller adjusts the liquid level in corresponding to antiresonance frequency; so that thefloating raft system can be always kept in the optimal vibration attenuation conditionregardless of the change of vibration frequency.