Dynamic Model of Full-scale Mr Dampers for Civil Engineering Applications

Magnetorheological (MR) dampers are one of the most promising new devices for structural vibration reduction. Because of their mechanical simplicity, high dynamic range, low power requirements, large force capacity, and robustness, these devices have been shown to mesh well with application demands and constraints to offer an attractive means of protecting civil infrastructure systems against severe earthquake and wind loading. Quasi-static models of MR dampers have been investigated by several researchers. Although useful for design of the damper, quasi-static models are not sufficient to describe the MR damper behavior under dynamic loading. This paper presents a new dynamic model of the overall MR damper system which is comprised of two parts: (i) a dynamic model of the power supply, and (ii) a dynamic model of the MR damper. Because previous studies have demonstrated that a current driven power supply can dramatically reduce the MR damper response time, this study employs a current driver to power the MR damper. The operating principles of the current driver, and an appropriate dynamic model are provided. Subsequently, MR damper response analysis is performed, and a mechanical model using the Bouc-Wen model is proposed to predict the MR damper behavior under dynamic loading. This model accommodates MR fluid inertial and shear thinning effects. Experimental verification has shown that the proposed dynamic model of the MR damper system predicts the experimental results very well.