Study on the effect of nonlinear inertia on the vibration isolation performance of quasi-zero-stiffness isolators

Typically, when subjected to excessive external force, quasi-zero-stiffness isolators with low damping will cause a sharp rightward bending of the transmissibility curve, resulting in a substantial decline in the performance of vibration isolation. The scheme with parallel tunable nonlinear inertia (PTNI) based on the triple-spring quasi-zero-stiffness (TS-QZS) isolator is designed to solve the above problems. To begin with, the kinetic equations are derived. Subsequently, the analysis of the primary response and stability involved the utilization of the Harmonic Balance Method (HBM), and the accuracy of the model was validated through numerical calculations. Finally, the impact of essential parameters is examined. The findings suggest that the QZS-PTNI isolator, without compromising the high frequency transmissibility, is capable of reducing peaks, suppressing the rightward trend of the transmissibility curve, narrowing the range of jump-up and jump-down frequency, and enhancing the vibration isolation performance.