Dynamic Analysis of Mechanical Controlled Two Degree-of-Freedom QZS Vibration Isolators

A basic one degree-of-freedom (1DOF) quasi-zero stiffness (QZS) vibration isolator is composed of two lateral springs used as negative stiffness mechanism and one vertical spring used as positive stiffness mechanism. Three types of two degree of freedom (2DOF) isolators are composed of the 1DOF isolators in series, namely grounded-grounded model (GGM), bottom-springs grounded model (BGM) and top-springs grounded model (TGM). In this paper, these three models are improved with a method of mechanical control and the displacement transmissibility equations of them are derived. Then, the simulation comparison is made. The results show that the performance of the three mechanical controlled models is significantly better than that of the former.