Study Of Particle Interaction In Giant Electrorehological Fluids

Electrorheological(ER) Fluid is a smart material in industry and its phase can be changed between solid and liquid within micro second. The yield stress of nanoscale giant electrorheological material is much larger than that of traditional electrorheological material. Giant electrorheological material has wide and important application value.It is found that well dispersed particles have much stronger attraction than those aggregated into clusters. In our simulation, there are 14 particles in each cluster of 250 nm in diameter. Under the same electric field, the yield stress of two particles in two adjacent clusters is found to be about 12 times smaller than that of two independent particles.We investigate the relations between the yield stress of polar-molecule dominated electrorheological (PM-ER) fluids and the shape of ellipsoidal particles. It is found that a shorter axis length of ellipsoidal particle along an external electric field increases an attractive force of two adjacent particles when the volume of one particle keeps constant. For example, the yield stress will increase 25 times when the axis length perpendicular to electric direction is 1.5 times as the sphere radius. This paper will also report that adding some ferroelectric materials in PM-ER fluid will make the long axis of particle perpendicular to electric direction so as to larger yield stress.