A novel integrated quasi-zero stiffness vibration isolator for coupled translational and rotational vibrations

Quasi-zero stiffness (QZS) vibration isolators can provide better isolation performance in the low frequency range than linear vibration isolators. Currently, most of the designed QZS isolators perform vibration isolation only in one direction and few papers are focused on simultaneously isolating the vibrations in two directions. In this paper, an integrated translational-rotational QZS vibration isolator is designed by using the cam-roller mechanism. The proposed QZS system is able to provide the high-static-low-dynamic stiffness in two directions simultaneously. The excitations in both translational and rotational directions are considered independent but with mutual interaction to their induced vibration response. The workable ranges of the QZS system and its limitations are first numerically identified. Then the static characteristics and typical nonlinear dynamic response with jump phenomena are theoretically investigated. The jump-down frequencies for small amplitude oscillations are determined from their amplitude-frequency relationships. Furthermore, the force transmissibility and moment transmissibility of the proposed QZS system are compared with those of the corresponding linear system without the cam-roller mechanism, which clearly demonstrate better isolation performance in both translational and rotational directions.