Rheological Properties of Magnetorheological Grease

Magnetorheological (MR) grease is known as a new class of MR material which consists of Carbonyl Iron (CI) particles suspended in the thixotropic medium to eliminate the sedimentation observed in the existing MR fluids. However, this newly developed MR medium still lacks the study on the effect of energy dissipation via shear oscillatory. Therefore, this study establishes dynamic viscoelastic properties of this medium using rotational and oscillatory shear rheometer under variation of magnetic fields and magnetic particles fractions. Enhancement of an off-state viscosity was due to the inherent high viscosity of grease property which was 1.9x10-4 m2 s-1. Conclusively, high dispersion of magnetic particles and good thermal properties were shown in the grease. This indicates that the newly developed MR grease can be applied in vibration control and damping systems such as seismic earthquake dampers.