An experimental study on thermo-field rheological properties of lithium-based magnetorheological grease

Abstract

In this paper, the effects of temperature and magnetic field strength on the dynamic rheological properties of magnetorheological grease are mainly studied. Firstly, the magnetorheological grease of carbonyl iron powder with a weight percentage of 70% was prepared by a mechanical stirrer. In steady state shear mode, the apparent viscosity and shear stress of lithium-based greases and magnetorheological greases at different magnetic field strengths and temperatures are measured. It is found that both apparent viscosity and shear stress decreased correspondingly with increasing temperature. Compared with the zero-field test results, the apparent viscosity of magnetorheological grease after applying a magnetic field is less affected by temperature. In addition, the Bingham model is combined with the Arrhenius model to derive mathematical formulas for shear yield stress and viscosity including temperature and magnetic field strength. Then, the dynamic rheological response behavior of magnetorheological grease at different temperatures is also tested, and the results showed that magnetorheological grease has viscoelastic properties. Finally, the stress-strain response parameter model of magnetorheological grease at different temperatures is established, and the parameters of the model are optimized by fish swarm algorithm. It is found that the model can describe the dynamic hysteresis response of magnetorheological grease very well.