Shear-Mode Rotary Magnetorheological Damper for Small-Scale Structural Control Experiments

Abstract

In an attempt to validate the effectiveness of a magnetorheological (MR) damper in controlling the wind-induced response of a building model in a wind tunnel, it is necessary to have a damper which produces a range of small forces so that it can be used to control the light-weight building model. In this study, a small-scale rotary type of MR damper is designed, manufactured, and tested. The damper uses shear-mode behavior of the MR fluids and is designed based on the simple Bingham viscoplastic model. A prototype damper that can produce forces in the order of a few newtons is made and tested in the laboratory. It is found that the Bouc-Wen model, which has been used to emulate linear valve-mode MR dampers, can also portray the hysteretic behavior of the shear-mode rotary damper. A simplified yet relatively accurate inverse dynamic model that can directly relate the damper force to the input voltage is proposed. Experiments demonstrate that a MR damper using this inverse model can closely reproduce prescribed forces. This inverse model provides an alternative means of commanding the MR damper for control applications.