| Some additional low-frequency noise generated during actuators working, they have a negative effect on pointing accuracy of the feed source and precise instrument. Considering the low-frequency vibration suppression in aerospace field, not only lowstiffness characteristic but also high load capacity could be met, which make vibration isolation a big issue. In this paper, a quasi-zero-stiffness(QZS) isolator is put forward which composed of the buckled Euler beams and spring, the former offer negative stiffness, the latter gives positive stiffness, therefore, the system has a low dynamic stiffness at the equilibrium position without sacrificing the support capacity. Specifically, the main contents and conclusions are as follows:According to the theory of large deflection, the mathematical model of QZS isolator which designed by combining negative stiffness Euler beams in parallel with a positive stiffness linear spring is built, expression of the restoring force and stiffness are obtained, as well as some parameter conditions to get zero stiffness at the equilibrium position. Using Taylor series expansion to simplify expression of the restoring force, then the Duffing equation is established and the frequency response curves are obtained by using the Harmonic Balance method for force excitation. There are some nonlinear phenomena such as frequency hopping and stiffness hardening characteristic, and enlarge the amplitude of excitation, nonlinear factor or reduce damping ratio of system can makes the nonlinear phenomena more outstanding, and the unstable frequencies interval expands The force transmissibility is studied combine with the equivalent linear system, the results demonstrate that QZS system is superior to the linear system for contain frequencies and some parameter conditions.QZS isolator’s FE and multi-body model is constructed by MSC. Patran and Adams, the multi-body consists of QZS isolators and satellite system. The structure’s stress as well as modal and vibration shape are described when it is under load and constraint conditions. Different types of excitations such as sine sweeping frequency signals and time domain transient signals can perform different responses. To compare and analyze the vibrating responses of attachments on the satellite, QZS isolators and rigid cone are chosen respectively to connect the satellite body and antenna. The results demonstrate that the vibration amplitude of antenna and feeds are evidently attenuated in low frequency by means of QZS isolators, and the decay time is reduced correspondingly.QZS isolator prototype is designed and assembled, both static load test and vibration test are conducted. The expression of restoring force depends on deformation is acquired. Develop dynamic test comparing QZS system and linear system to analyze the force transmissibility, the results indicate that two different jump-down frequencies are derived as QZS system under a forward and reverse sweeping frequencies, the interval between two frequencies is extending when amplitude of the excitation increasing, but linear system is not the case. In addition, QZS system has an unstable isolation effect in the low range of frequency, but it will make an excellent performance until frequency comes to 4.2Hz. On the whole, QZS system expends vibration isolation interval, and has a preferable vibration suppression.The theoretical and experimental research about QZS isolator put forward in the paper will play an instructive role in application of spaceflight. |
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