Transient responses of magnetorheological elastomer and isolator under shear mode

Magnetorheological elastomer (MRE)-based smart devices have been widely studied as versatile real-time actuators for the application of efficient control of vibration systems. However, the inherent time delay that exists in MRE actuators may cause performance degradation or even lead to system instability. The purpose of this paper is to explore the response time of a vibration isolation system based on an MRE isolator working in shear mode, and analyze its relative influence factors. The transient response tests are set up under various step currents and static shear strains. Furthermore, the response time of the MRE material is identified by model fitting with the separation of current response time. The results reveal that the response time of MRE isolator is composed primarily of current response (rests with current drive unit and coil configuration unit), magnetic flux density response (comes from eddy currents) and shear force response (derives from the response of the MRE material and the electro-magneto-mechanical coupling behavior of isolator). As with MREs, the response time of MRE isolators mainly hinges on the variation of transient current amplitude, but does not highly correlate to the shear strain. This paper also offers advice on minimizing the response time from various aspects, by analyzing the transient response. Besides the intrinsic importance of contributing to the response evaluation and effective design of MRE actuators, this study will also conduce to the optimal design of controllers for MRE real-time control systems.