Theoretical design on the characteristics of a hexagon quasi- zero stiffness vibration isolator

Abstract

A novel hexagon quasi-zero stiffness (QZS) platform using link-spring mechanism is proposed with load adjustable to seek for low-frequency vibration isolation. First, the key static characteristics, such as the elastic potential energy, restoring force and effective stiffness are obtained by mechanical modeling for different configurations of the platform. It indicates that the proposed structure could achieve dynamic zero stiffness for different designed loading capacity, even a full band vibration isolation. Then, the nonlinear properties of inertia, stiffness and damping are systematically studied and it is proven to be beneficial for dynamic stabilization and vibration isolation. An analytical expression for the effective stiffness is derived to obtain parameter condition for QZS characteristic. Finally, the displacement transmissibility of the structure is solved by the harmonic balance method. The results demonstrate that the hexagon QZS vibration isolator has low and tunable frequency for vibration isolation and outperforms the linear isolators. Comparing to the classical QZS vibration isolator, the proposed one has a wider zero stiffness plateau and the starting frequency of vibration isolation can be as low as 1/4 that of the classical one. Consequently, the hexagon QZS isolator should be a feasible design for vibration isolation in ultralow frequency range.