Induced stress and particle behavior of the electro-rheological suspensions at higher shear rates probed by electrical and mechanical responses

Induced stress and current response were investigated at higher shear rates for the electro-rheological (ER) suspensions. In relation between stress and shear rate for a typical ER suspension, the flow was well assumed to the Bingham flow with the yield stress depending on the strength of the electric field. On the other hand, the stress for a dilute suspension with a higher viscosity of continuous phase showed a remarkable dip behavior at higher shear rates: The stress decreased with an increase in the shear rate above a critical shear rate, and it gradually increased again. The apparent conductivity, which was investigated at the same time and closely related to the aggregated structure of polarized particles in the ER suspension, also probed the corresponding behavior to the dip of the stress. Applicability and limitation of the Bingham flow at the higher shear rates were also discussed using a dimensionless parameter.