Dynamic analysis and experiment of Quasi-zero-stiffness system with nonlinear hysteretic damping

Nonlinear Quasi-zero-stiffness (QZS) vibration isolation systems with linear damping cannot lead to displacement isolation with different excitation levels. In this study, a QZS system with nonlinear hysteretic damping is investigated. The Duffing-Ueda equation with a coupling nonlinear parameter eta is proposed to describe the dynamic motion of the QZS system. By using the harmonic balance method (HBM), the primary and secondary harmonic responses are obtained and verified by numerical simulations. The results indicate that nonlinear damping can guarantee a bounded response for different excitation levels. The one-third subharmonic response is found to affect the isolation frequency range even when the primary response is stable. To evaluate the performance of the QZS system, the effective isolation frequency Omega(e), and maximum transmissibility T-p are proposed to represent the vibration isolation range and isolation effect, respectively. By discussing the effect of eta on Omega(2), and T-p, the conditions to avoid nonlinear phenomena and improve the isolation performance are provided. A prototype of the QZS system is then constructed for vibration tests, which verified the theoretical analysis.