Viscous and damping properties of magnetorheological fluids containing needle-like nonmagnetic particles

Abstract

Magnetorheological fluids containing nanometer size needle-like nonmagnetic particles whose long axis is 194 nm and aspect ratio is 8.3 are prepared as new magnetic functional fluids. Viscous properties of the fluids are investigated experimentally. Shear stress and viscosity coefficient are measured by using the rheometer which has the additional equipment for measurement in the presence of magnetic field. When the total volume fraction of the particles in the fluid is constant (0.30), larger amount of needle-like particles in the fluid gives larger viscosity in the absence of magnetic field. In the contrast, the viscosity and shear stress of the fluid containing 4% needle-like nonmagnetic particles and 26% micrometer sphere magnetic particles take large value than those of other fluids in the presence of magnetic field.