Rheology and microstructural evolution in pressure-driven flow of a magnetorheological fluid with strong particle–wall interactions

Ocalan, Murat; McKinley, Gareth H.

doi:10.1177/1045389x11429601

Cited by 11 publications

(8 citation statements)

References 23 publications

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“…Interestingly, the difference in moduli curves in figure 2(e) suggests a change in the failure mode between the two fluids. Specifically, the cMRF shows a rapid decline in both G ′ and G ′′ prior to ultimate failure that may be the result of slip, which is known to occur in MR fluids and has been mitigated in the past using experimental changes such as using roughened or ferromagnetic plates [25,34]. Strikingly, the stMRF did not exhibit this slip phenomena, which we hypothesize was due to the shear thickening nature of the fluid.…”

Section: Resultsmentioning

confidence: 85%

Shear thickening prevents slip in magnetorheological fluids

Rendos¹,

Woodman²,

McDonald³

et al. 2020

Smart Mater. Struct.

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Magnetorheological (MR) fluids are smart fluids that solidify upon the application of a magnetic field by virtue of suspended magnetic particles forming chains. Here, the effect of shear thickening additives on the performance of MR fluids is explored and found to increase yield stress by 60% in fluids that have the same iron content. In order to explore the origin of this improvement, a series of flow-and oscillation-based rheology experiments were performed at various plate separations and the results were compared with a discrete dipole model of chain formation and breakage. Ultimately, conventional MR fluids, which are typically shear thinning, are found to yield at small strains that are consistent with slip failure where chains shear apart at one particle-particle joint. In contrast, shear thickening fluids reliably yield at high strain in a manner consistent with affine failure of the chain where each joint is pulled apart equally. The prevention of slip failure is attributed to the shear thickening additive locally increasing the effective viscosity as slip begins, thus preventing it from leading to yield. In addition to motivating the use of shear thickening agents broadly in MR fluids, these findings highlight the importance of additive choice in tuning rheological properties of MR fluids and the benefit of considering the microstructural and bulk behavior of the fluid simultaneously when synthesizing smart fluids.

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Section: Resultsmentioning

confidence: 85%

Shear thickening prevents slip in magnetorheological fluids

Rendos¹,

Woodman²,

McDonald³

et al. 2020

Smart Mater. Struct.

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“…Moreover, it was assumed that the MR fluid was homogenous in the control volume. However, it can be expected that the magnetophoretic force [25] causes the migration of particles in the fluid due to the magnetic flux density gradient. Therefore, the concentration of ferromagnetic particles (density) in the active zone was not constant and the magnetic properties (relative permeability, magnetic saturation, etc.)…”

Section: Fe Calculationsmentioning

confidence: 99%

Assessment of the Dynamic Range of Magnetorheological Gradient Pinch-Mode Prototype Valves

Žáček,

Goldasz,

Sapinski

et al. 2023

Actuators

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Magnetorheological (MR) fluids have been known to react to magnetic fields of sufficient magnitudes. While in the presence of the field, the material develops a yield stress. The tunable property has made it attractive in, e.g., semi-active damper applications in the vibration control domain in particular. Within the context of a given application, MR fluids can be exploited in at least one of the fundamental operating modes (flow, shear, squeeze, or gradient pinch mode) of which the gradient pinch mode has been the least explored. Contrary to the other operating modes, the MR fluid volume in the flow channel is exposed to a non-uniform magnetic field in such a way that a Venturi-like contraction is developed in a flow channel solely by means of a solidified material in the regions near the walls rather than the mechanically driven changes in the channel’s geometry. The pinch-mode rheology of the material has made it a potential candidate for developing a new category of MR valves. By convention, a pinch-mode valve features a single flow channel with poles over which a non-uniform magnetic field is induced. In this study, the authors examine ways of extending the dynamic range of pinch-mode valves by employing a number of such arrangements (stages) in series. To accomplish this, the authors developed a prototype of a multi-stage (three-stage) valve, and then compared its performance against that of a single-stage valve across a wide range of hydraulic and magnetic stimuli. To summarize, improvements of the pinch-mode valve dynamic range are evident; however, at the same time, it is hampered by the presence of serial air gaps in the flow channel.

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“…To explore the microscopical behaviour of the MRF, past studies have mainly used bright field microscopy [12], [13]. Their observations revealed the variation in the distribution of ferromagnetic particles in the MRF if a magnetic field was applied to the fluid [14].…”

Section: Introductionmentioning

confidence: 99%

“…Their observations revealed the variation in the distribution of ferromagnetic particles in the MRF if a magnetic field was applied to the fluid [14]. In order to perform the measurements, different setups have been developed and used, but most of them were using a Polydimethylsiloxane (PDMS) microchannel with a magnetic circuit surrounding it, to apply the magnetic field on the MRF [12], [13]. In the current work, the variations of the MRF magnetic properties are studied with a measurement setup similar to a valve.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic device for analysis of magnetorheological fluids’ properties

Loayza

Ntella

Mohaghegh

et al. 2022

2022 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM)

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The valve mode is the most common operational mode of magnetorheological fluid (MRF) devices in engineering applications. Magnetorheological (MR) valves have been studied upon their self-sensing capabilities resulting from the electromagnetic induction phenomenon. In parallel, studies have been carried out regarding the microstructural properties and the analytical modeling of MRFs used in valves. This paper presents the design and fabrication of a microfluidic system in the form of a magnetic circuit, consisting of a MRF flow channel, with dimensions close to those of previously studied miniaturized MR valves. The channel is enclosed in ferromagnetic and transparent sheets. The sheets facilitate the magnetic field distribution, created by a coil. The channel allows the microscopical MRF particles observation and their correlation with the MRF magnetic and rheological properties when the self-sensing phenomenon occurs.

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Rheology and microstructural evolution in pressure-driven flow of a magnetorheological fluid with strong particle–wall interactions

Cited by 11 publications

References 23 publications

Shear thickening prevents slip in magnetorheological fluids

Shear thickening prevents slip in magnetorheological fluids

Assessment of the Dynamic Range of Magnetorheological Gradient Pinch-Mode Prototype Valves

Microfluidic device for analysis of magnetorheological fluids’ properties

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