MAGNETORHEOLOGY OF FERROFLUID COMPOSITES

Composites consisting of nonmagnetic particles with sizes in the micron range suspended in a ferrofluid constitute an inverse magnetorheological fluid. Structuring occurs in an applied magnetic field and can result in the solidification of the composite. Above a critical level of applied stress the material further transforms to a liquid state. Data confirming the existence of a solidified state are presented based on constant shear theological measurements. Measurements of the yield stress compare favorably with predictions of theory based on the analysis of unsymmetric stresses in the unyielded, anisotropic medium.