Instabilities of a pressure-driven flow of magnetorheological fluids

Rodríguez‐Arco, Laura; Kuzhir, Pavel; López–López, Modesto T.; Bossis, Georges; Durán, J.D.G.

doi:10.1122/1.4810019

Cited by 7 publications

(3 citation statements)

References 41 publications

(45 reference statements)

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“…Aside from the pressure oscillations, the experiment repeatability is acceptable. Rodriguez et al [28] observed a similar trend curve as in the present study. The authors stated that the non-monotonic shape of these curves could be explained in terms of the competition between the two opposite effects: (a) an increase of the hydrodynamic dissipation and (b) weakening of the interaction between aggregates and walls during the suspension flow velocity increase.…”

Section: Effect Of Magnetic Fieldsupporting

confidence: 91%

Magnetorheological fluids subjected to non-uniform magnetic fields: experimental characterization

Kubík¹,

Gołdasz²,

Macháček³

et al. 2023

Smart Mater. Struct.

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Magnetorheological (MR) fluids are suspensions of fine, low-coercivity, high-magnetizable particles in a continuous liquid phase. When subjected to magnetic field, the material exhibits a rapid change in the apparent viscosity of several orders of magnitude. This unique capability has been successfully exploited in automotive semi-active suspensions systems or systems for manufacturing high quality optics. In a majority of the existing systems the rheology of MR fluids is controlled by an external uniform field oriented perpendicularly to the fluid flow direction. In general, it is an inherent feature of MR systems operating in flow, shear or squeeze modes, respectively. There is an experimental evidence that the behavior of MR fluids in the so-called pinch-mode (in which the fluid is subjected to non-uniform magnetic field distributions ) clearly stands out against the remaining three operating modes. With the predecessors, the flow through the channel occurs once a pressure across it exceeds the field-dependent threshold pressure. For comparison, in pinch mode valves the magnetic flux energizes mostly the layers of the materials near the channel walls. The outcome is a change in the channel’s effective diameter achieved solely via material means without changing its geometry. To study the fluid’s unique behaviour in the mode the authors designed a prototype valve assembly and examined several fluid formulations of various particle concentration levels across a wide range of external (velocity, magnetic field density) stimuli in an organized effort to further comprehend the phenomenon. The obtained data indicate that the magnitude of the particular effect does not only depend on the magnitudes of the magnetic stimuli but also on the particle concentration. In general, the authors believe that the study may provide guidelines as to the selection of fluid formulations for developing novel valveless actuators utilizing MR fluids operating in pinch mode.

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Section: Effect Of Magnetic Fieldsupporting

confidence: 91%

Magnetorheological fluids subjected to non-uniform magnetic fields: experimental characterization

Kubík¹,

Gołdasz²,

Macháček³

et al. 2023

Smart Mater. Struct.

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“…Исследования физических свойств жидких намагничивающихся сред были начаты еще в XX в. с изучения магнитных и реологических свойств суспензий [1]. Практическое использование магнитореологических суспензий (MR -Fluids) основано на очень сильной зависимости вязкости от напряженности магнитного поля, благодаря чему магнитореологические суспензии нашли применение в тормозных устройствах [1][2][3][4]. Недостатком такого рода дисперсных систем является их нестабильность, необратимое разделение магнитной и немагнитной фаз под действием силы тяжести или неоднородного магнитного поля.…”

Section: Introductionunclassified

Damping of an Oscillatory System with Incomplete Sealing of the Air Cavity by a Magnetic Fluid

Shel’deshova,

Churaev,

Ignatenko

et al. 2023

jour

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Purpose. Investigate the damping of an oscillatory system with incomplete sealing of the air cavity with a magnetic fluid.Methods. The study was carried out on an experimental setup developed on the basis of known methods and equipment for magnetic measurements and manufactured independently. A ring neodymium magnet (NdFeB alloy) 60x24x10 mm in size was used as a magnetic field source. The magnetic field strength at the center of the magnet, measured with a TPU-01 milliteslamer, is 220 kA/m. An inductor, a GVT-427B amplifier, and a GwInstek GDS-72072 digital oscilloscope were used to display oscillograms. Samples of magnetic fluid based on Fe3O4 magnetite stabilized with oleic acid were studied. Kerosene was used as the carrier liquid.Results. The results of an experimental study of the elasticity and damping of an oscillatory system with incomplete sealing of the air cavity by a magnetic fluid bridge are presented. The level of sealing of the air cavity varies due to the process of pumping gas through capillaries of various radii. To explain the regularities obtained, a model theory is proposed in the approximation of a viscous gas flow according to the Poiseuille law, and the conclusions of the wellknown theory of sound propagation in molecular acoustics and the theory of sound ducts are also drawn. The relaxation mechanism imposes a restriction on the type of vibrational gas flow through the capillaries, which takes into account the "throughput" capacity of the capillaries. The proposed model explains the presence of a maximum in the dependence of the attenuation coefficient on the capillary radius and its decrease with an increase in the volume (height) of the gas cavity.Conclusion. The proposed relaxation theory of vibrational gas flow through capillaries predicts anomalously large damping coefficients and almost complete damping of an oscillatory system with a magnetic fluid inertial element. The use of the data obtained is advisable in the design of new shock absorbers, since a magnetic fluid damper with capillaries is capable of damping low-frequency oscillations.

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“…In the usual way, an MRP is prepared by dispersing micron-sized magnetic or magnetizable particles into magnetically insensitive, soft polymer matrixes. An MRP behaves as an intermediate state between traditional fluid-like magnetorheological fluid (MRF) [2][3][4][5][6] and conventional solid-like magnetorheological elastomers (MREs) [7][8][9]. In contrast to the easily sedimentary MRF and the relatively low-magnetorheological-effect MRE, an MRP attractively possesses long-time stability and a higher magnetorheological effect.…”

Section: Introductionmentioning

confidence: 99%

Magneto-induced large deformation and high-damping performance of a magnetorheological plastomer

Liu

Gong

et al. 2014

Smart Mater. Struct.

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A magnetorheological plastomer (MRP) is a new kind of soft magneto-sensitive polymeric composite. This work reports on the large magneto-deforming effect and high magneto-damping performance of MRPs under a quasi-statical shearing condition. We demonstrate that an MRP possesses a magnetically sensitive malleability, and its magneto-mechanical behavior can be analytically described by the magneto-enhanced Bingham fluid-like model. The magnetoinduced axial stress, which drives the deformation of the MRP with 70 wt % carbonyl iron powder, can be tuned in a large range from nearly 0.0 kPa to 55.4 kPa by an external 662.6 kA m −1 magnetic field. The damping performance of an MRP has a significant correlation with the magnetic strength, shear rate, carbonyl iron content and shear strain amplitude. For an MRP with 60 wt % carbonyl iron powder, the relative magneto-enhanced damping effect can reach as high as 716.2% under a quasi-statically shearing condition. Furthermore, the related physical mechanism is proposed, and we reveal that the magneto-induced, particle-assembled microstructure directs the magneto-mechanical behavior of the MRP.

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Instabilities of a pressure-driven flow of magnetorheological fluids

Cited by 7 publications

References 41 publications

Magnetorheological fluids subjected to non-uniform magnetic fields: experimental characterization

Magnetorheological fluids subjected to non-uniform magnetic fields: experimental characterization

Damping of an Oscillatory System with Incomplete Sealing of the Air Cavity by a Magnetic Fluid

Magneto-induced large deformation and high-damping performance of a magnetorheological plastomer

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