DEPENDENCE OF ELECTRORHEOLOGICAL RESPONSE ON CONDUCTIVITY AND POLARIZATION TIME

The mechanisms which govern the performance of electrorheological (ER) fluids must be established if the response times and electrostress le vels required for industrial applications are to be achieved. Earlier work by this group has led to a comprehensive description of the elect rical and pressure response observed in engineering scale ER valve sys tems operating under realistic conditions. The present paper carries t his program further by showing that in this regime the measured ER val ve characteristics are consistent with the polarization-conductance me chanism commonly taken to be the basis for the generation of electrost ress. Theoretical descriptions of ER fluids often ignore the role of c onductance and frequency dependence of the permittivity. Here, within the context of a model incorporating these material properties and a p olarization time, we examine factors affecting the speed, form, and ma gnitude of ER response. Using this model we are able to establish a re lationship between the experimentally observed pressure and current fo r biased sine and step voltage excitation.