Displacement Transmissibility of Nonlinear Isolation System with Magnetorheological Damper

To improve the performance of single-stage vibration isolation system, the influence of the nonlinear magnetorheological (MR) damper on isolating the vibration from the base excitation was investigated. Being different from the traditional single degree of freedom (DOF) vibration isolation model, an unconstrained two DOF vibration isolation model is proposed, which contains the influence of the base mass. A revised Bingham model is adopted to describe the nonlinear damping force of MR damper. After reasonable assumptions, the displacement response under harmonic excitation is obtained using averaging method which is verified by numerical solution. The absolute displacement transmissibility is used to evaluate the dynamic characteristic of nonlinear isolation system. Parametric analysis is conducted to investigate the influence of the system parameters on improving transmissibility. The increase of MR parameters all obviously suppress the primary resonance response but reduce isolation effect in the high frequency. The increase of base mass can improve vibration isolation effect in the isolation frequency region but enlarge the resonance peak. These conclusions are of significant importance in the analysis and design of vibration attenuation system with MR damper.