Nonlinear variable-stiffness vibration isolator with electromagnetic shunt damper

Abstract High-static-low-dynamic-stiffness (HSLDS) vibration isolation systems, owing to their inherent nonlinearities, are prone to jump phenomena under high excitation amplitudes, leading to impaired low-frequency vibration isolation performance. To address this issue, this paper proposes a hybrid magnetic HSLDS isolator with an integrated electromagnetic shunt damper (EMSD), which is designed based on the principle of eddy current effects. This isolator can achieve superior low-frequency vibration isolation performance through active regulation of system stiffness and damping. First, the nonlinear magnetic force of the isolator and the electromagnetic coupling coefficient of the EMSD are derived. In addition, a negative resistance circuit based on an operational amplifier is designed to reduce the system impedance and enhance the damping force. Based on this, an electromechanically coupled, two-degree-of-freedom dynamic model of the isolator is developed to analyze its low-frequency vibration isolation performance. Experiments are performed to validate the effectiveness of the system in regulating both stiffness and damping. Additionally, an adaptive regulation strategy is proposed based on the experimental results; this strategy enables the system to adaptively adjust its stiffness and damping in response to variations in the vibration source frequency. Experimental results indicate that, compared to the passive state, the isolator employing the regulation strategy exhibits a 16.6% reduction in the initial isolation frequency and a 46.7% attenuation of the resonance peak. Optimal vibration suppression is achieved across the full frequency band.