A compact magnetic-curved-spring QZS isolator for supporting uncertain loads

Leveraging the superior vibration isolation performance of nonlinear stiffness, this paper proposes a magnetic-curved-spring isolator (MCSI) with quasi-zero stiffness property. The positive stiffness of this isolator is composed of repulsive magnets, while the negative stiffness is composed of a cam-roller-spring mechanism. The vibration isolation mechanism formed by the parallel connection of the two can adapt well to the isolation under different loads. To gain an in-depth understanding and verify the performance of the dual-nonlinear stiffness vibration isolator, its static restoring force is analyzed and its dynamic response is acquired via harmonic balance method, then the stability analysis is conducted. The obtained displacement transmissibility reflects its low resonance frequency and wide isolation frequency band. By constructing an experimental platform and applying sweep frequency-, periodic- and random excitations, the experiments show that the MCSI can achieve low-frequency isolation from 3 Hz. Compared with linear isolation, it demonstrates the superiority of the developed nonlinear isolator for supporting uncertain loads. Our proposed MCSI features adjustable positive and negative stiffness, being adaptable to various working environments, thus offering a novel approach to the design of vibration isolators.