Simulated and experimental studies on a high-static-low-dynamic stiffness isolator using magnetic negative stiffness spring

For the purpose of isolating the low frequency vibration, a magnetic vibration isolator with the feature of high-static-low-dynamic stiffness (HSLDS) is developed in this paper, which is constructed by combining a magnetic negative stiffness spring (MNSS) with a spiral flexure spring (SFS) in parallel. The MNSS comprises three magnetic rings configured in attraction and is utilized to reduce the resonant frequency of the isolator. Then an analytical expression of magnetic negative stiffness (MNS) of the MNSS is deduced in terms of the current model, and an approximation to the MNS is further sought. To support the object, the axial positive stiffness of SFSs, which can behave with a smaller static deformation if a specified weight is applied, is analyzed with finite element method (FEM). After that, the governing equation of the isolator is established and solved via harmonic balance method (HBM). Finally, an experimental prototype is developed and tested. The experimental results demonstrate that the MNSS can reduce the resonant frequency of the isolator to expand the isolation frequency band to low frequency range; and the theoretical calculations and experimental results shows a good agreement.