Magnetorheological fluid

About: Magnetorheological fluid is a research topic. Over the lifetime, 8538 publications have been published within this topic receiving 131502 citations. The topic is also known as: MRF & MR fluid.

Material Behaviour New magnetorheological elastomers based on polyurethane/Si-rubber hybrid

Abstract: A type of magnetorheological elastomer based on polyurethane (PU)/silicone rubber (Si-rubber) hybrid was fabricated without applying a magnetic field. The MR effect was improved by optimizing preparation conditions, in particular by adjusting the PU/Si-rubber ratio, and improving compatibility between PU and Si-rubber. The influences of the preparation conditions and the relationship between the microstructure and MR effect of this kind of magnetorheological elastomer are discussed in detail. The results show that this kind of MR elastomer has better MR effect than that of MR elastomers based on pure Si-rubber or PU matrix with the same testing conditions. SEM analysis indicates that the former forms a peculiar interpenetrating microstructure in the presence of PU in the matrix. The maximum increase in shear modulus of this kind of MR elastomer can be up to 0.5 MPa when exposed to a magnetic field of about 0.2 T. q 2004 Elsevier Ltd. All rights reserved.

Design Analysis and Experimental Evaluation of an MR Fluid Clutch

Abstract: An MRC (Magneto-Rheological Clutch), a device to transmit torque by shear stress of MR fluids, has the property that its power transmissibility changes quickly in response to control signal. In this study, we consider methods to predict performance of an MRC. First, we anticipate the performance of an MRC with a simplified mathematical model and second, we predict the performance in consideration of the applied magnetic field and viscosity distribution of fluids caused by the field. Between the two methods, compared with experimental results, it is shown that the numerical method is closer to reality than the simplified one.

Study of magnetorheological fluids at high shear rates

Abstract: The tunable rheological properties of magnetorheological (MR) materials at high shear rates are studied using a piston-driven flow-mode-type rheometer. The proposed method provides measurement of the apparent viscosity and yield stress of MR fluids for a shear rate range of 50 to 40,000 s−1. The rheological properties of a commercial MR fluid, as well as a newly developed MR polymeric gel, and a ferrofluid-based MR fluid are investigated. The results for apparent viscosity and dynamic and static shear stresses under different applied magnetic fields are reported.

Rheological properties of magnetorheological suspensions based on core–shell structured polyaniline-coated carbonyl iron particles

Abstract: The sedimentation caused by the high density of suspended particles used in magnetorheological fluids is a significant obstacle for their wider application. In the present paper, core–shell structured carbonyl iron–polyaniline particles in silicone oil were used as a magnetorheological suspension with enhanced dispersion stability. Bare carbonyl iron particles were suspended in silicone oil to create model magnetorheological suspensions of different loading. For a magnetorheological suspension of polyaniline-coated particles the results show a decrease in the base viscosity. Moreover, the polyaniline coating has a negligible influence on the MR properties under an external magnetic field B. The change in the viscoelastic properties of magnetorheological suspensions in the small-strain oscillatory shear flow as a function of the strain amplitude, the frequency and the magnetic flux density was also investigated.

Viscometric and Sedimentation Characterization of Bidisperse Magnetorheological Fluids

Abstract: Magnetorheological fluids (MRFs) are typically thought of as Bingham-plastic (BP) fluids characterized by a yield stress. Partial substitution of micrometer-scale Fe particles with nanometer-scale Fe particles leads to bidisperse MRFs. This partial substitution mitigates particle sedimentation, but can reduce yield stress for high nanoparticle concentrations. We examine tradeoffs between increasing suspension stability versus decreasing in yield stress as nanoparticles are substituted for microparticles. Four groups of fluids with total Fe concentration of 50, 60, 70, and 80 wt% were considered. A sedimentation measuring device quantified sedimentation velocity of MRFs in a gravitational field. This sensor relates the rate of change of inductance relative to settling rate as Fe wt% decreases because of sedimentation. MRF flow curves were measured using a parallel disk rheometer and yield stress was identified using the BP flow model.