Theoretical Design and Analysis of a Nonlinear Electromagnetic Vibration Isolator with Tunable Negative Stiffness Characteristic

Abstract

A novel tunable negative stiffness nonlinear electromagnetic isolator is presented, it includes a vertical positive stiffness spring, an electromagnetic spring constructed by two permanent magnets and an electromagnet. The electromagnetic isolator can act as a passive isolator or a semi-active control one. The mathematical expression of system stiffness-current-displacement is derived by analyzing the mechanical characteristics. The motion differential equation under an external harmonic excitation force is established. The amplitude-frequency relationship of the system is deduced by the averaging method. The global dynamic behavior on the Van der pol plane and the force transmissibility are researched. The results show that the nonlinear electromagnetic isolator with appropriate parameters can enlarge the low frequency isolation range and make the system have better isolation performance in the low frequency band. The nonlinear electromagnetic isolator with suitable system parameters has the advantages of widening the vibration isolation range and improving the low-frequency vibration isolation effect.