Nonlinear dynamic characteristics of load adaptive quasi-zero stiffness vibration isolator based on electromagnetic and disc spring

Abstract

To improve low-frequency vibration isolation under varying payloads, a load-adaptive quasi-zero-stiffness (QZS) configuration combining disc springs and a parallel electromagnetic element is theoretically and numerically investigated. Static and nonlinear dynamic models are established, and the harmonic balance method is used to analyze the frequency-response characteristics. The nonlinear model is further transformed into an equivalent quasi-linear form, and an LQR controller is introduced for active vibration suppression. Electromagnetic stiffness regulation is employed to compensate for payload-induced variations in the equivalent system stiffness. For payloads ranging from 17 to 25 kg, electromagnetic stiffness regulation reduces the relative resonance angular-frequency variation from 19.49% without regulation to 0.09% with regulation, corresponding to a reduction of approximately 99.54%. Adams/View simulations show vibration-suppression trends consistent with the theoretical predictions, with peak displacement and velocity reductions of approximately 59.5% and 59.4%, respectively. These results provide additional numerical support for the effectiveness of the proposed framework in suppressing resonance-frequency drift and improving low-frequency vibration isolation under varying payload conditions.