关键词: 非线性系统, 负刚度, 隔振, 谐波平衡法

Abstract: An Euler buckled beam formed negative stiffness mechanism is proposed and the static characteristic of which is analyzed. A quasi-zero stiffness isolator is designed by parallel connecting the negative stiffness mechanism and a linear isolator. The Euler buckled beam structure functions as a stiffness corrector to lower the stiffness of the linear isolator. If the load is chosen properly, the equilibrium point will be set at the zero stiffness point, any changes of the load will lead the equilibrium point deviating from the zero stiffness point. The dynamic model is built considering the load effect and the harmonic balance method is employed to solve for the dynamic response of the system. Force transmissibility of the zero guasi-stiffness isolator is defined and compared with that of an equivalent linear one. The effect of excitation amplitude and load on the performance is analyzed. The results show that the force excitation amplitude and load can change the characteristic of the nonlinear isolator from a hardening stiffness system to a softening stiffness system and even a mixed softening-hardening stiffness system. The excitation amplitude and load also have great affection on the transmissibility performance.

Key words: Harmonic balance method, Negative stiffness, Nonlinear systems, Vibration isolation