Effect of temperature on rheological properties of lithium-based magnetorheological grease

Abstract

This paper investigates the impact of temperature on the rheological properties of magnetorheological (MR) grease containing carbonyl iron suspended in lithium-based grease within the temperature range from 10℃ to 70℃under influence of temperature, i.e. from 10℃ to 70℃. Lithium-based MR grease with 70% weight fraction of carbonyl iron has beenis firstly prepared by mechanical mixing. The apparent viscosity and shear stress as a function of shear rate under different temperatures and magnetic field strengths are measured and discussed. It is found that the influence of temperature on apparent viscosity is reducingreduces with the increase of magnetic field strength. In addition, in the presence of magnetic field, maximum yield stress gets demonstrates an increase as temperature increases from 50℃ to 60℃. The dynamic properties of MR grease are obtained under oscillatory shear test. The influences of strain amplitude, driving frequency and magnetic field on the dynamic properties of MR grease at different temperature are discussed. The results demonstrate that the enhancement of temperature leads to the increase of storage modulus and the reduction of the loss factor. Microstructural variation of grease matrix at different temperature is proposed as an explanation of the rheological changes of MR grease.

Rheological Properties of Polyurethane-Based Magnetorheological Gels

“…It can be concluded that the ability of energy storage for PU matrix decreases with the increase of shear strain amplitude. With the influence of the magnetic flux density, as can be seen in Figures 6B-E, MR gels exhibit obvious linear viscoelastic region at the small strain range, which was the same as the dynamic properties of MR grease (Wang et al, 2019). It should be noted that the data is plotted with logarithmic horizontal axis to clear present the linear region.…”

Magneto-induced rheological properties of magnetorheological gel under quasi-static shear with large deformation

“…10(a) that the inuence of magnetic elds on the storage modulus of MRG shows a decreasing trend with increasing of magnetic elds, resulting from the gradually saturated magnetic particles in MRG. 34 Therefore, the gaps between the steady-state value of storage modulus decrease progressively with the increasing of magnetic elds. 35 On the other hand, taking MRG-40 for example, storage modulus appears a rising trend with the enlargement of frequency at rst and then gets a plateau gradually.…”

Normal force of lithium-based magnetorheological grease under quasi-static shear with large deformation

“…viscosity, yield stress, storage modulus and loss modulus. [11][12][13][14][15][16] The normal force of the MR materials is the force induced by the forming of chain or cluster structure along the direction of the magnetic eld which is perpendicular to the shear stress. This normal force has signicant impacts on the mechanical performance of MR materials-based devices and is suggested to be considered in the design stage of MR devices.…”