Experimental study of the yield stress of electrorheological suspensions under AC field: Comparison with a theoretical model

Recently a model describing the interaction between the particles of an electrorheological suspension and the resulting properties (yield stress, current density) has been proposed by Wu and Conrad. This model takes into account both the conductivity and the permittivity of each constituent of the suspension and predicts the behavior under DC and AC fields. The goal of the present work is to compare the predictions of this model with data available in the literature and with additional experiments using DC and AC fields at frequencies up to 2000 Hz. The ER fluids used in our experiments are suspensions of different ceramics particles (Al2O3, ZrO2,TiO2, CaTiO3, BaTiO3) in silicone oil. These particles cover a wide range of permittivity and conductivity, which allows us to study the ER effect with varying values of die conductivity and/or permittivity mismatch between the particles and the liquid. The model is in reasonable accord with experiment.