Dynamic performance of quasi-zero-stiffness isolator with displacement-dependent electromagnetic shunt damping

Since the damping force of electromagnetic shunt damping (EMSD) devices can be adjusted by controlling the external circuit, in order to further enhance its vibration reduction performance in the resonance region of the vibration isolation system, a displacement-dependent electromagnetic shunt damping (D-EMSD) system is developed by incorporating a sliding rheostat. Utilizing the approximate analytical solution solved via the harmonic balance method, the dynamic performance of a quasi-zero-stiffness (QZS) isolator integrated with a D-EMSD are examined. Concurrently, the stability conditions for the steady periodic solutions are deduced employing the Lyapunov first method and the Routh-Hurwitz stability criterion. A comprehensive analysis is conducted on the influence of the D-EMSD and various system parameters on the amplitude-frequency response and force transmission characteristics of the primary QZS system. The results show that D-EMSD can simultaneously decrease the peak values of amplitude and force transfer rate within the main resonance zone, which improves the vibration isolation capability of QZS system for the main resonance zone without compromising high-frequency isolation capability.