Magnetic field-dependent dynamic behavior of magnetorheological grease composite in a wide temperature range: Experiment and modeling

Investigating the intricate magneto -induced dynamic behavior of Magnetorheological (MR) grease is a prerequisite for the design of its devices. This paper is mainly concerned with comprehensive experimental and modeling research of the magneto -induced dynamic characteristics over a wide temperature range. Firstly, a labprepared lubricant grease matrix was used to produce a MR grease that exhibits as soft matter under zero field condition, and its magneto -induced dynamic shear properties under the temperature range of -10 degrees C to 150 degrees C was tested by three types of experiments, i.e., oscillatory strain amplitude, oscillatory frequency and magnetic field sweeps. Secondly, the temperature dependent dynamic behavior of MR grease, i.e., stress -strain hysteresis characteristics and storage/loss modulus variation, under different strain amplitudes, frequencies and magnetic fields is discussed and analyzed in detail. The variation of the stress -strain hysteresis suggests that MR grease exhibits thermal -softening effect in the absence of magnetic field, while it demonstrates thermo-stiffening in the presence of magnetic field. The study of storage/loss modulus reveals a pronounced sensitivity to variations in magnetic field, temperature, and strain magnitude, with the exception of oscillation frequency, which exhibits relatively lower sensitivity. Furthermore, within the linear viscoelastic range, both storage modulus and loss modulus are associated with the critical magnetic field, leading to a response that is completely opposite across the temperature range from -10 degrees C to 150 degrees C. Finally, a model consisting of a five -parameter viscoelastic element and Arrhenius equation was proposed to predict the magnetic field- and temperature -dependent storage/loss modulus of MR grease under different oscillatory strain amplitudes and frequencies, and the effectiveness of the model was verified by comparing experimental and simulated results.