Nonlinear Energy Sink-Enhanced Hybrid Vibration Isolator with Quasi-Zero-Stiffness and Nonlinear Inerter for Broadband Suppression

The quasi-zero-stiffness (QZS) vibration isolator exhibits superior low-frequency vibration isolation performance. However, its nonlinear hardening stiffness induces a rightward shift of the resonance peak, thereby narrowing the effective isolation bandwidth. Conversely, integrating a nonlinear inertance mechanism (NIM) into a linear isolator enhances vibration isolation performance by shifting the force transmissibility curve toward the low-frequency regime. Nevertheless, this configuration may amplify peak dynamic response amplitudes under large excitations. This paper proposes a new design of a nonlinear energy sink (NES) attached to a NIM-QZS hybrid vibration isolator (HVI). The vibration control performance of HVI-NES system consists of a QZS system, a NIM system and a NES is investigated. Firstly, the governing dynamic equations are derived, and the amplitude-frequency response and force transmissibility curves of the HVI-NES system are analytically obtained using the harmonic balance method coupled with an arc-length continuation technique. The analytical results are validated through numerical simulations. Secondly, the effect of the NES on the force transmissibility and frequency response of the primary structure is examined. Parameters study is conducted to assess the effects of the cubic nonlinear stiffness coefficient, mass ratio, and damping ratio. Thirdly, the control performance of the HVI-NES system is analyzed in terms of varying excitation. In addition, the parameters optimization of the NES is conducted. Furthermore, parameter optimization of the NES is performed, leading to the design rule for the NES attached to the HVI system. Finally, a comparison of control performance with other four models is conducted, demonstrating its superior performance in broadband vibration suppression. The results demonstrate that the NES effectively reduces the peak response amplitude of the HVI system. Furthermore, the HVI-NES configuration exhibits superior vibration control efficacy compared to the QZS isolator.