A novel quasi-zero-stiffness isolation platform via tunable positive and negative stiffness compensation mechanism.

Various quasi-zero stiffness (QZS) systems with high-static and low-dynamic stiffness (HSLDS) have been applied extensively to attenuate low-frequency vibrations. However, in the majority of cases, the negative stiffness unit exhibits nonlinear stiffness behaviors, and the method of realizing QZS is limited to compensate the nonlinear negative stiffness through linear springs. Hence, a novel linkage anti-vibration structure (LAVS) via linear positive and negative stiffness compensation mechanism is proposed and studied for exploring its advantages in low-frequency vibration isolation. The LAVS is composed of a symmetric polygonal structure (SPS) and a vertical spring. The static stiffness behavior is first investigated, revealing the inherent positive and negative stiffness compensation mechanism of linear springs to the SPS. By tuning structural parameters, the linear spring can completely compensate the linear negative stiffness of the SPS to achieve enhanced QZS over a larger stroke. Numerical simulations are carried out to verify the theoretical result and demonstrate the effectiveness of the presented stiffness compensation mechanism. Based on the Lagrange principle, a dynamic equation is established and then solved via the multiple scales method to obtain the displacement transmissibility. The effects of key parameters such as the rod lengths, equilibrium points and damping factors on the amplitude–frequency characteristics and vibration transmissibility are analyzed. Compared with a SMD and a typical X-shaped QZS isolation systems, the presented LAVS exhibits an enhanced QZS zone with a larger load capacity and can realize superb vibration isolation performance with guaranteed stable equilibrium. The proposed linear positive and negative stiffness compensation mechanism presents new insights for passive vibration isolation design in many engineering applications. [ABSTRACT FROM AUTHOR]