A PRELIMINARY PARAMETRIC STUDY OF ELECTRORHEOLOGICAL DAMPERS

In approaching the design of an electrorheology-based, semi-active sus pension, the electrorheological component (ER damper) can be built as either a flow-mode, shear-mode, or mixed-mode type of damper. The sour ce of damping force in the flow-mode is exclusively from flow-induced pressure drop across a valve, while that in the shear-mode is purely f rom the shear stress on a sliding surface. The dynamics of the fluid f low are included in the derivation of the zero-field damping forces. T he control effectiveness is found to be strongly related to the dynami c constant (which is proportional to the square root of the vibration frequency) and, for shear- and flow-mode dampers, the ratio of the pis ton area to the cross-section of the ER control gap. To achieve the sa me performance, a flow-mode ER damper is not as compact and efficient as a shear-mode ER damper. With the same ER damping force, a mixed-mod e damper is more compact than a shear-mode damper. However, the mixed- mode damper does not have as a low zero-field damping force as the she ar-mode damper. The analysis is based on the assumption that the ER fl uid is Bingham plastic.