Multi-direction vibration isolation with tunable QZS performance via novel X-mechanism design

Passive vibration suppression in multiple directions is highly demanded in engineering practices. Based on the X-shaped mechanism, a planar 3-DOF passive vibration isolation with a tunable QZS mechanism is proposed in this study. A specially designed adjustable X-mechanism is integrated with a supporting X-structure to achieve considerable flexibility and easiness in nonlinear stiffness design of a compact 3-DOF passive vibration isolation platform. The novel mechanism design enables the anti-vibration unit to achieve adjustable and beneficial nonlinear stiffness, damping characteristics and excellent ultra-low-frequency vibration isolation performance in all three directions simultaneously. Analyses of loading capacity, nonlinear static stiffness, and QZS zone in the three directions are conducted to better demonstrate the proposed vibration isolator. Comparative studies with traditional spring-mass-damper (SMD) isolators and other typical QZS isolators show that, the proposed vibration isolation unit exhibits much wider QZS zone, larger loading capacity, and wider vibration isolation band in all three directions. The nonlinear statics and tunable QZS effect in three individual directions, and the advantageous vibration isolation performance in the main anti-vibration direction of the proposed passive vibration isolation unit are validated with experimental studies. The results demonstrate a new approach to achieving adjustable nonlinear stiffness and damping design for multiple direction vibration control based on the very rich properties of X-shaped structures/mechanisms.