Abstract: We presented a modified conductivity model for the attractive force of a perfect particle chain in a nonpolar liquid. With the concept of equivalent plate thickness, we calculated the periodic electric field in a chain and the periodic charger in the plate surfaces. We obtained the total attractive force of particles with a linear superposition method where the multi-particle effect in a perfect chain was concerned. We also compared the predicted quasistatic yield stress with the experiment data of two materials, Alooh/Silicone oil and Zeolite/Silicone oil, and found they are in a well agreement.

Key words: electrorheological fluids, conductivity model, equivalent plate thickness, yield stress