Two-sided damping constraint control strategy for high-performance vibration isolation and end-stop impact protection

In this paper, a two-sided damping constraint control strategy is proposed to improve the performance of the quasi-zero stiffness isolator. The new control policy is achieved through switching the damping of isolator between the soft and hard modes that depend on a preset value of the relative displacement (PRD). This control approach can largely lower the isolation frequency while enhancing the effectiveness of isolation in high frequencies and preventing the severity of end-stop impacts. To realize such control objective, two key issues are solved including the suppressing of period-3 solutions that coexist with the desired period-1 orbits and the optimization of PRDs based upon the analysis of two-parameter bifurcations and basins of attraction. Finally, the capability of the proposed system in end-stop impact protection is studied, which shows that it can successfully prevent the impact and quickly stabilize the large-amplitude response into the ideal steady-state motion.