A semi-active electromagnetic quasi-zero-stiffness vibration isolator

A semi-active electromagnetic quasi-zero-stiffness (QZS) vibration isolator (VI) (SEQZS VI) is proposed to broaden the frequency bandwidth for low or ultra-low frequency vibration isolation. The electromagnetic negative stiffness mechanism (NSM) applies a newly designed 8-shaped electromagnetic equivalent magnetic circuit and has a more extensive tunable range of negative stiffness (NS) than previous studies. Moreover, theoretical formulations for the SEQZS VI in static and dynamic analyses under harmonic excitations were derived in detail and the parameter analysis is carried out to provide a reference for the design. Furthermore, a prototype is fabricated and tested to validate the design concept of SEQZS VI. The experimental results validate the present formulation and show that the vibration isolation performance of the proposed SEQZS VI is much better than that of the corresponding linear isolator. Moreover, the present SEQZS VI can have lower stiffness in a wider region and lower transmissibility at the resonance frequency.

Automated summary

A semi-active electromagnetic quasi-zero-stiffness (QZS) vibration isolator (VI) has been proposed to expand the frequency bandwidth for low or ultra-low frequency vibration isolation. The innovative electromagnetic negative stiffness mechanism (NSM) utilizes an 8-shaped electromagnetic equivalent magnetic circuit, providing a wider tunable range of negative stiffness compared to previous studies. Theoretical formulations for the SEQZS VI, including static and dynamic analyses under harmonic excitations, have been derived and parameter analysis has been conducted for design reference. Experimental results from a prototype verify the effectiveness of the SEQZS VI, which outperforms linear isolators in terms of vibration isolation performance and exhibits lower stiffness and transmissibility at the resonance frequency.