Dependence of electrorheological response on conductivity and polarization time

Abstract

The mechanisms which govern the performance of electrorheological (ER) fluids must be established if the response times and electrostress levels required for industrial applications are to be achieved. Earlier work by this group has led to a comprehensive description of the electrical and pressure response observed in engineering scale ER valve systems operating under realistic conditions. The present paper carries this program further by showing that in this regime the measured ER valve characteristics are consistent with the polarization-conductance mechanism commonly taken to be the basis for the generation of electrostress. Theoretical descriptions of ER fluids often ignore the role of conductance and frequency dependence of the permittivity. Here, within the context of a model incorporating these material properties and a polarization time, we examine factors affecting the speed, form, and magnitude of ER response. Using this model we are able to establish a relationship between the experimentally observed pressure and current for biased sine and step voltage excitation.