Abstract
In an effort to increase the shear yield stress of dielectric electrorheological fluids, we focus on the electrostatic force of different forms of particles in a dielectric polarization model. By solving Laplace‘s equation and applying the multiple image method and the finite element method, the analytical and numerical solutions of the electrostatic force of a two-sphere structure have been studied. The results suggest that when the dielectric mismatch factor is large and when the positions of the two spheres are nearly in contact with each other, most of the analytical solutions either over-or underestimate the force. Additionally, the structure of particles beyond the spherical form is considered. Three example cases are studied to shed light on how different geometries of particles may affect the electrostatic force, thereby influencing the shear yield stress of the fluid.
Highlights
Electrorheological (ER) fluids are regarded as smart fluids, whose resistance to flow can be quickly and dramatically altered by an applied electric field
We consider dielectric electrorheological (DER) fluids, which are made of micrometer-sized dielectric particles in an electrically insulating liquid
The shear yield stress of a general DER material is typically of several kPa when subjected to an electric field of 1-5 V mm 1
Summary
Electrorheological (ER) fluids are regarded as smart fluids, whose resistance to flow (from a liquid to a solid gel, and back) can be quickly (with response times on the order of milliseconds [1]) and dramatically altered by an applied electric field. We consider dielectric electrorheological (DER) fluids, which are made of micrometer-sized dielectric particles in an electrically insulating liquid. The shear yield stress of a general DER material is typically of several kPa when subjected to an electric field of 1-5 V mm 1. Charges polarized in an electric field tend to concentrate at certain positions of the particles surface so that the charges can be used efficiently to increase the shear yield stress. To the best of our knowledge, work of such nature has not yet been performed Various investigations, such as of particle patterns, arrangement structures, surface/core dielectric properties and interface structures, could be conducted to characterize the fluids. We proceed to consider three special cases beyond the basic form as a demonstration, which provides several ideas to increase the shear yield stress in the experiment.
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