Investigation on the design of magnetic spring-beam vibration isolator with negative stiffness characteristic

To improve the performance of vibration isolator in the low frequency region, a magnetic spring-beam vibration isolator with the high-static-low-dynamic stiffness (HSLDS) characteristic is developed in this paper. The proposed isolator is designed by combining a negative stiffness magnetic spring (NSMS) in parallel with an Euler-Bernoulli beam. The NSMS comprising four magnet pairs is utilized to reduce the resonant frequency of the isolator. An analytical expression of the negative stiffness (NS) of the NSMS is derived according to the Amperian current model, and the approximation to NS is deduced. Based on the harmonic balance method (HBM), the dynamic response of the isolator is obtained and the impacts of external force and damping ratio on the force transmissibility are investigated numerically. The simulated results demonstrate that the NSMS can effectively reduce the resonant frequency of the isolator and broaden the bandwidth for vibration isolation. Also the damping property of the isolator with NSMS is improved.