A Novel QZS Isolator Based on Spring-Link Mechanism and Its Optimal Design

Quasi-zero stiffness (QZS) isolators provide superior isolation performance than linear isolators in low-frequency vibration conditions. This paper presents a novel nonlinear vibration isolator and its optimized model based on a spring-link mechanism, which exhibits favorable QZS characteristics in a specific vibration interval. First, a uniaxial spring-link isolator (USLI) is proposed. Zero stiffness condition at the static equilibrium position is applied to achieve the optimized QZS characteristics of the system, based on which, parameter characteristics are clearly analyzed. The harmonic balance method (HBM) is employed to obtain the steady-state response under harmonic force excitations and the force transmissibility, which will be used to evaluate the vibration isolation performance. The effects of the value of independent parameters on dynamic response and system stability are clearly analyzed. Subsequently, a biaxial spring-link isolator (BSLI) which consists of multi-axis mechanisms is proposed on the basis of USLI. Through the comparative analysis of the vibration isolation performance by numerical and simulation methods between the linear isolator, three-spring QZS isolator (TSI), USLI and BSLI, it is verified that the two QZS isolators proposed in this paper can effectively suppress the peak response and force transmissibility, and exhibit significantly enhanced isolation performance than linear isolators and TSI under low-frequency excitation vibration conditions. Meanwhile, the modified BSLI performs improved isolation effectiveness and enhanced stability of the system compared with USLI. The results in this paper provide effective insights and methods for the design, analysis, and mechanism optimization of QZS isolators.