Analysis and experiment of a novel compact magnetic spring with high linear negative stiffness

Improving the isolation performance of vibration isolators by introducing magnetic negative stiffness mechanisms (NSMs) has attracted extensive attention in recent years. Nevertheless, common magnetic NSMs are always accompanied by nonlinear stiffness, resulting in degradation of isolation performance and system instability when subjected to excitations with large amplitude. To improve the stiffness linearity and working range of magnetic NSMs in a limited space, a novel compact magnetic spring with high linear negative stiffness (CMS-HLNS) is proposed in this paper. The CMS-HLNS consists of two sets of permanent magnets (PMs) arranged in an alternate manner, which has both high linearity and high negative stiffness properties. A simplified analytical stiffness model of the CMS-HLNS is deduced based on the magnetic charge method. The effects of design parameters on the stiffness characteristics of the CMS-HLNS are investigated. Finally, experimental prototypes are constructed to verify the feasibility of the analytical model and the superior vibration isolation performance when introducing the CMS-HLNS. The experimental results demonstrate that the CMS-HLNS can achieve linear negative stiffness in a large working range under the constraint of space and is suitable for (ultra-) low-frequency isolation under excitations with large amplitude. It's believed that the magnetic spring proposed in this paper can be applied as an innovative technology in engineering practice, and its good linearity and compact structure make it extremely adaptable.

Automated summary

The paper proposes a novel compact magnetic spring with high linear negative stiffness (CMS-HLNS) to improve the isolation performance of vibration isolators. The CMS-HLNS consists of two sets of permanent magnets arranged alternately, which has both high linearity and high negative stiffness properties. A simplified analytical stiffness model is derived based on the magnetic charge method, and the effects of design parameters on the stiffness characteristics are investigated. Experimental prototypes are constructed to verify the feasibility of the analytical model and demonstrate the superior vibration isolation performance of the CMS-HLNS under large amplitude excitations.