An adjustable low frequency vibration isolation with high-static-stiffness low-dynamic-stiffness property using a novel negative stiffness element

Abstract

A vibration isolator with a novel negative stiffness element (NSE) configured with two electromagnetic springs in parallel was proposed in this study. The electromagnetic force and stiffness model of NSE was built based on the Ampere current model and filament method, the effect of configuration parameters on the negative stiffness was investigated in detail. The linear negative stiffness principle was proposed based on the impact of height difference on the nonlinear component sign of the negative stiffness, and the linear negative stiffness parameter design strategy for NSE was also developed. The isolator prototype was fabricated with the parameter design result, and the correctness of modeling and principle for linear negative stiffness were validated by magnetic force measurement. A series of experiments under different coil currents and vibration amplitude was conducted. The results show that high-static-stiffness and low-dynamic-stiffness property of the isolator is realized, the resonant frequency is 3.85 Hz with the coil current is 1A is reduced by up to 58.5% compared with the resonant frequency when coil without energized, the isolation bandwidth has been stretched and can be adjusted by coil current and performance has been significantly improved also. In addition, the isolator is stable and the performance is not deteriorator under different vibration amplitudes.