Temperature Dependence of Magneto-rheological Materials

The properties of magneto-rheological (MR) materials are temperature dependent. Compared to MR fluids, MR greases (MRGs) are more sensitive to temperature due to their inherent behavior of carrier materials. In this study, MRGs are studied to examine the temperature effect on their yield stress and apparent viscosity. Experimental data are obtained for magnetic fields ranging from 0.14 T to 0.53 T and temperatures ranging from 10 degrees C to 70 degrees C. It is observed that temperature has a significant effect on the field-induced yield stress of MRGs. Anew yield stress model, based on an extended Herschel-Bulkley constitutive relation, in which the shear yield stress is a function of magnetic field and temperature, is proposed. Excellent agreement between the theoretical results and experimental data is obtained.