Enhanced vibration isolation performance of quasi-zero-stiffness isolator by introducing tunable nonlinear inerter

The concept of quasi-zero-stiffness (QZS) vibration isolator was proposed inrecent decades aiming at improving the low-frequency isolation performance in a passive manner. However, large excitation and small damping usually cause the transmissibility curve to bend seriously to the right, which greatly reduces the effective isolation region. This paper focuses on enhancing the QZS isolator by introducing tunable nonlinear inerter (TNI). After formulating the dynamic equation, the response is analytically calculated, the stability is analyzed, and numerical simulations are conducted. By comparing the isolation performances of the QZS isolator and the QZS-TNI isolator, it is shown that adding the inerter can considerably suppress the bending trend of the transmissibility curve, thereby resulting in a much wider frequency range of isolation as well as a lower peak transmissibility.