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A model for the particle-particle interaction in a chain of spherical particles in an electrorheological (ER) fluid is developed based on an expansion of the potential which satisfies the Laplace equation. The electric-field distribution and force-distance relationship between particles are calculated as a function of Kp/Kf (the dielectric constant of the sphere relative to that of the medium) and particle-particle spacing using this model. The calculations predict electric-field concentrations of about an order of magnitude near particle contacts. This gives a force between particles that is approximately an order of magnitude higher than predicted by the classical point-dipole approximation, and is in reasonable agreement with that measured experimentally. Subtle effects of the carrier fluid on the interaction force and an explanation for the non-Ohmic behavior of ER fluids are deduced in terms of its dielectric constant and dielectric strength.

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The complex moduli of a composite consisting of a hollow beam filled with an electrorheological (ER) fluid were obtained by analyzing the beam's motion in free oscillation. The beam was considered to be a uniform viscoelastic material and was modeled as a damped harmonic oscillator. Hydrous-based ER fluids consisting of either cornstarch-corn oil or zeolite-silicone oil mixtures with varying amounts of solids and water content were employed, along with electric field intensities ranging from 0.0 to 1.7 × 10 3 kV/m. Rheological data were also obtained for the fluids A linear correlation between the two components of the moduli and fluid strength was observed, which was explained in terms of fluid structure and particle polarization ,I. of INTELL MATER SYST. AND STRUCT, hol.

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