Theoretical and experimental investigations on semi-active quasi-zero-stiffness dynamic vibration absorber

A semi-active quasi-zero-stiffness (QZS) dynamic vibration absorber (DVA) (SAQZS DVA) is proposed to broaden the frequency bandwidth for ultra-low frequency vibration absorption. The SAQZS DVA is constructed by embedding an electromagnetic actively regulatory mechanism (ARM) into a QZS DVA to fulfill tuning capability of vibration absorption. The restoring force and stiffness of the SAQZS DVA are investigated theoretically to demonstrate how the ARM performs by tuning the current in the coils. Then, the complicated expression of the restoring force of the SAQZS DVA is fitted by polynomial approximation, and the frequency-amplitude response is obtained analytically. The results show the SAQZS DVA enables vibration absorption at an ultra-low frequency, and the anti-resonance frequency for vibration absorption can be tuned effectively. Furthermore, the prototype of the SAQZS DVA is built, and the verification experiment is carried out. The results indicate that the antiresonance frequency for vibration absorption can be tuned from 3. 86 Hz to 4.67 Hz. Moreover, a remarkable reduction in acceleration amplitude can be observed when the anti-resonance frequency is tuned to match the excitation frequency by adjusting the ARM. Consequently, the SAQZS DVA should be a feasible way for vibration absorption tuning in ultra-low frequency range.