Summary An inerter‐based quasi‐zero stiffness (IQZS) vibration isolator is proposed to further enhance the dynamic performance of the QZS one. It combines the superior nonlinear stiffness characteristic of the QZS vibration isolator and the beneficial mass magnification effect of the inerter. The diamond‐shaped structure is used as the negative stiffness structure; an additional spring is added together with the inerter and damper to construct a novel IQZS vibration isolator, which the inerter and damper are first parallel connected and then series connected with the additional spring; it is a mixed‐connected (MC) type and termed as MC‐IQZS vibration isolator. The dynamic response of MC‐IQZS vibration isolator is acquired via harmonic balance method (HBM), and the isolation performance is evaluated using four performance criteria. The effects of the inerter and additional spring on its dynamic response and isolation performance are examined. The results show that the MC‐IQZS vibration isolator could have smaller displacement amplitude and force transmissibility peaks, wider isolation frequency band, and faster high‐frequency force transmissibility attenuation rate than the QZS one, and it can improve the four performance criteria simultaneously. Its isolation performance is further compared with another two typical types of IQZS vibration isolators where the inerter and damper are in parallel‐connected (PC) and series‐connected (SC), respectively, and they are denoted as PC‐IQZS and SC‐IQZS vibration isolators, respectively. The results demonstrate that the proposed MC‐IQZS vibration isolator could achieve the best isolation performance among the three IQZS ones, which offers an effective option for excellent vibration suppression in practical engineering.

A nonlinear stiffness and nonlinear inertial vibration isolator is proposed in this article. It consists of an inerter, a damper, and spring elements. The nonlinear stiffness characteristic is achieved through a negative stiffness structure based on the diamond-shaped structure that generates nonlinear displacement terms. The nonlinear inertial characteristic is implemented via a geometrical nonlinear inerter that produces a nonlinear acceleration term and a nonlinear quadratic velocity term. An averaging method is developed to analyze approximately the dynamic response. The isolation performance is evaluated using four performance criteria: dynamic displacement peak, force transmissibility peak, isolation frequency band, and high-frequency force transmissibility. The effects of the nonlinear inertial characteristic on the dynamic response and isolation performance are examined. The results show that the backbone curve of the nonlinear stiffness and nonlinear inertial vibration isolator has two changing trends: bending first to the right and then to the left and bending directly to the left. The corresponding frequency response curve displays linear, hardening, and softening characteristics. The isolation performance of the nonlinear stiffness and nonlinear inertial vibration isolator is compared with that of the nonlinear stiffness and nonlinear stiffness and linear inertial ones. It could achieve a smaller force transmissibility peak, lower resonant frequency, and larger isolation frequency band than the nonlinear stiffness one and could have smaller dynamic displacement peak and smaller high-frequency force transmissibility than the nonlinear stiffness and linear inertial one. The proposed nonlinear stiffness and nonlinear inertial vibration isolator achieves a better integrated isolation performance among the three vibration isolators.

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