Design And Research On Dynamic Characteristics Of A New Quasi-Zero Stiffness Isolator

Although traditional passive vibration isolators can effectively isolate vibration in the high frequency range,it is often difficult to achieve good vibration isolation effects due to the natural frequency limitation of the vibration isolator in the low frequency range,but decreasing the natural frequency will inevitably reduce the carrying capacity of the isolator.Therefore,how to keep the isolator with a high static stiffness while maintaining a low dynamic stiffness is a difficult problem in the development of passive isolators.The quasi-zero stiffness vibration isolator combines positive and negative stiffness mechanisms to ensure that the vibration isolation system has a certain bearing capacity while achieving the characteristics of zero dynamic stiffness near the equilibrium point,so that the vibration isolation system also has a strong strength in low frequency.Based on the research of traditional quasi-zero stiffness isolators,a new quasi-zero stiffness isolators are designed and their dynamic characteristics are analyzed.The main research contents of this article are as follows:A classical spring-based quasi-zero stiffness vibration isolator is researched.A four-spring structure vibration isolator is designed,its dynamic model under simple harmonic force excitation is established,and its amplitude-frequency characteristic curve and force transmission rate curve is used to study the changing trend of the system curve under the influence of different parameters.A new type of quasi-zero stiffness vibration isolator is proposed,which uses an air cylinder instead of a spring to make its actual stiffness adjustable.The dynamic equation is established,the amplitude-frequency phase-frequency equation of the system is obtained by using the harmonic balance method,the amplitude-frequency characteristic curve of the system is drawn,the displacement transfer model is established,and the parameters affecting the displacement transfer rate are analyzed.When the load mass deviates from the rated mass,the quasi-zero stiffness system loses the quasi-zero stiffness characteristic near the static equilibrium position.At this time,the nonlinear characteristics of the system become more apparent.A dynamic model was established for this situation,and its amplitude-frequency characteristics were analyzed.For the subharmonic resonance and chaos phenomena that may exist,its bifurcation with frequency was studied.The phase diagram,Poincaré section and Lyapunov exponent were used to confirm the existence of chaos,numerical simulations were used to verify the correctness of the analytical solution.Based on the characteristic that the stiffness of the cylinder was adjustable,a solution to the load deviation was given.