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.

Constitutive models of electrorheological and magnetorheological fluids using viscometers

Abstract: A key aspect of application of electrorheological (ER) and magnetorheological (MR) fluids is the characterization of rheological properties. In this study, two rotational viscometers to measure the field-dependent flow behavior (shear stress versus shear rate) of ER/MR fluids are theoretically analyzed. One is a rotational coaxial cylinder viscometer, and the other is a rotational parallel disk viscometer. The equations between shear stress and torque as well as shear rate and angular velocity are derived on the basis of the Bingham-plastic, biviscous, and Herschel–Bulkley constitutive models. The shear stress for the rotational coaxial cylinder viscometer can be straightforwardly calculated from the measured torque. However, in order to determine the shear rate, three approximation methods are applied. Meanwhile, the shear stress and shear rate in the rotational parallel disk viscometer can be obtained directly from the torque and angular velocity data. In order to comprehensively understand the flow behavior of ER/MR fluids with respect to the constitutive models, nondimensional analyses are undertaken in this study.

Magnetorheological fluids: characterization and modeling of magnetization

Abstract: This paper presents a magnetization model that endeavors to capture the change in the rheological behavior due to the application of magnetic fields to ferrofluids (FFs) and magnetorheological fluids (MRFs). Samples of Ferrotec APG 2115 FF and Lord MRF-122-2ED MRF have been tested using an Anton Paar MCR 501 rotational rheometer fitted with a parallel-plate measuring system. On the basis of the results, the FF has been modeled using the Newtonian model whereas the MRF has been adjusted using the Bingham and Herschel–Bulkley models. All three models have been extended using the herein-proposed magnetization model, that provides good adjustment of any of the models to the entire range of applied magnetic field.

Harmonic analysis of a magnetorheological damper for vibration control

Abstract: Semi-active control systems are becoming more popular because they offer both the reliability of passive systems and the versatility of active control systems without imposing heavy power demands. In particular, it has been found that magnetorheological (MR) fluids can be designed to be very effective vibration control actuators, which use MR fluids to produce controllable damping force. The objective of this paper is to study a single-degree-of-freedom (SDOF) isolation system with an MR fluid damper under harmonic excitations. A mathematical model of the MR fluid damper with experimental verification is adopted. The motion characteristics of the SDOF system with the MR damper are studied and compared with those of the system with a conventional viscous damper. The energy dissipated and equivalent damping coefficient of the MR damper in terms of input voltage, displacement amplitude and frequency are investigated. The relative displacement with respect to the base excitation is also quantified and compared with that of the conventional viscous damper through updating the equivalent damping coefficient with changing driving frequency. In addition, the transmissibility of the MR damper system with semi-active control is also discussed. The results of this study are valuable for understanding the characteristics of the MR damper to provide effective damping for the purpose of vibration isolation or suppression.

Experimental investigations into forces during magnetorheological fluid based finishing process

Abstract: Magnetorheological fluid based finishing process is a fine finishing process that has been applied to a large variety of brittle materials, ranging from optical glasses to hard crystals. Under the influence of a magnetic field, the carbonyl iron particles (CIPs) and non-magnetic polishing abrasive particles remove material from the surface being polished. Knowledge of forces acting is important to understand the mechanism of material removal. A dynamometer and virtual instrumentation are used to on-line record the normal force and tangential force acting on the workpiece through the magnetorheological (MR) fluid. A full factorial design of experiments is used to plan the experiments and ANOVA to correlate the forces and process parameters. The selected process parameters (volume concentration of CIPs and abrasives, working gap, and wheel rotation) are varied over a range to measure forces during experimentation. The maximum contribution is made by a working gap on the forces developed on the workpiece surface followed by CIP concentration while the least contribution is noticed by the wheel speed.