Relationship between conductive uniformity of electrorheological fluid particles and the electrorheological effect

Electrorheological fluids (ERF) consist of semi-conductive particles in an insulating oil. The conductive uniformity of the particles is one of the most important factors affecting the electrorheological (ER) performance. Wt: investigated the possibility of determining the conductive uniformity of ER particles by dielectric dispersion measurements and the relationship between ER performance and conductive uniformity, as measured by this technique. We used carbonaceous particles and dimethyl silicone oil To estimate the conductive uniformity of ER particles, we used the a parameter that can be obtained from the dielectric Cole-Cole expression. We find that the ER effect (viscosity increase) strongly depends on the particles' conductive uniformity: when the conductivity is less uniform, the ER effect will be lower than expected from an ideal model. We are therefore now able to predict qualitatively the ER performance by measuring dielectric dispersion.