Dual quasi-zero-stiffness dynamic vibration absorbers for double-low-frequency vibration suppression

Generally, a dynamic vibration absorber (DVA) is effective in suppressing single-frequency vibration, which would be unworkable for double-frequency vibration. This study introduces a dual quasi-zero-stiffness dynamic vibration absorber (DQZS-DVA) as a solution to this problem. Firstly, the DQZS-DVA with a pair of mutually exclusive permanent magnets as the negative stiffness mechanism (NSM) is designed, and its static characteristics are theoretically analyzed. Next, the Harmonic Balance Method (HBM) is used to derive an approximate analytical solution, and the effect of system parameters on the dynamic characteristics of the primary oscillator is discussed. In addition, the dynamic behavior of the primary oscillator under a random or impulse excitation is numerically analyzed. The results demonstrate that the DQZS-DVA exhibits excellent vibration suppression under double-low-frequency harmonic, random, and impulse excitations. The anti-resonance frequency of the system with the DQZS-DVA can be reduced by 50 % compared to the linear DVA. Furthermore, the system parameters of the DQZS-DVA are optimized using the fixed-points theory to further improve the vibration suppression performance. Finally, a prototype of the DQZS-DVA is manufactured, and verification experiments are conducted. The experimental results confirm that the DQZS-DVA can suppress vibrations with double low frequencies of 3.5 Hz and 7.0 Hz. More importantly, the design procedure of the DQZS-DVA should be a valuable guide for dealing with the scenario when the primary oscillator suffers from an excitation with three or more frequencies.