Characteristics Analysis And Experimental Research On Quasi-Zero-Stiffness Vibration Isolation System Based On SD Oscillator

The precision instrument is subjected to low-frequency vibration during vehicle transportation,which has a bad influence on the precision instrument.Thus it has certain theoretical signficance and application value to study the theory of vibration isolation for the precision instrument and to research the quasi-zero-stiffness(QZS)isolation system.Based on the nonlinear response characteristics of SD oscillator,a type of the QZS isolator with the characteristics of high-static-low-dynamic stiffness is investigated in this paper,and the dynamic characteristics of the isolator are analysed.The results of vibration experiments prove that the QZS isolator has the excellet vibration isolation performance,which provides a reference for engineering application.The QZS isolation system with sleeve structure is established,and the amplitude-frequency responses of the QZS isolator subjected to harmonic excitation and the harmonic forcing excitation are derived with averaging method.The displacement transmissibility and force transmissibility of the model are calculated,and the theoretical results show that the QZS system has the perfect vibration isolation performance.The bifurcation diagram,history diagram,spectrum,phase portrait and poincare section are figured by means of numerical simulation to reveal the complex dynamic phenomenon of the system.The QZS isolation system with sleeve structure is designed and fabricated,and experimental system is constructed.The amplitude-frequency responses of the system under different amplitude of harmonic excitation and different excitation frequency are investigated by the displacement transmissibility experiments,and the displacement transmissibility of the QZS isolator is derived.It is founded that the experimental results are coincided with the theoretical analysis,which proves that the QZS isolation system with sleeve structure is efficient.Based on the displacement transmissibility experiments,the random excitation experiments of the QZS vibration isolator are executed to research the isolationperformance of the system subjected to random excitation.According to the comparative test,it is founded that the QZS isolation system can be superior to linear one in performance of low-frequency and broadband vibration isolation.