On a quasi-zero stiffness vibration isolator with multiple zero stiffness points for mass load deviation

This paper proposes a quasi-zero stiffness (QZS) isolator with three zero stiffness (ZS) points to cope effectively with mass load deviations. Most of the existing QZS vibration isolators are designed for a single mass. The vibration isolation performance of the isolator is significantly affected when the mass load deviates after the structure has been determined. The isolators designed in this paper have multiple ZS points, thereby enlarging the QZS interval while effectively reducing the sensitivity to mass changes. The dynamic equations of the system are constructed based on the Lagrange equation, and the influence of the parameters on the stiffness characteristics is analyzed thoroughly. The modified incremental harmonic balance method (IHB) is applied to analyze the dynamic characteristics of the vibration isolator, and the effects of different masses, different stiffness characteristics, and mass variation under fixed excitation on the vibration isolation performance are discussed separately. The presence of stiffness-softening intervals effectively suppresses the impact of stiffness-hardening on vibration isolation performance. The QZS isolator can effectively solve the problem of deviation of the isolated mass when the system stiffness fluctuation is small. The same isolator can simultaneously satisfy the vibration isolation requirements of three different masses when stiffness fluctuations are large. The results of this paper provide a research idea for overcoming the shortcomings of QZS vibration isolators, which are sensitive to mass changes, and for realizing effective vibration isolation for multiple masses.