This paper investigates a nonlinear inertance mechanism (NIM) for vibration mitigation and evaluates the performance of nonlinear vibration isolators employing such mechanism. The NIM comprises a pair of oblique inerters with one common hinged terminal and the other terminals ﬁxed. The addition of the NIM to a linear spring-damper isolator and to nonlinear quasizero-stiﬀness (QZS) isolators is considered. The harmonic balance method is used to derive the steadystate frequency-response relationship and force transmissibility of the isolators subject to harmonic force excitations. Diﬀerent performance indices associated with the dynamic displacement response and force transmissibility are employed to evaluate the performance of the resulting isolators. It is found that the frequency response curve of the inerter-based nonlinear isolation system with the NIM and a linear stiﬀness bend towards the low-frequency range, similar to the characteristics of the Duﬃng oscillator with softening stiﬀness. It is shown that the addition of NIM to a QZS isolator enhances vibration isolation performance by providing a wider frequency band of low amplitude response and force transmissibility. These ﬁndings provide a better understanding of the functionality of the NIM and assist in better designs of nonlinear passive vibration mitigation systems with inerters.
- Nonlinear vibration isolator ·
- Force transmissibility
- Nonlinear inertance mechanism
- Backbone curve
- Quasi-zero stiffness