Wall material and roughness effects on transmittable shear stresses of magnetorheological fluids in plate–plate magnetorheometry

Laun, H. M.; Gabriel, Claus; Kieburg, Christoffer

doi:10.1007/s00397-011-0531-8

Cited by 35 publications

(18 citation statements)

References 13 publications

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“…However, as observed, values of the shear stress for a given value of the shear rate were considerably higher for measuring plates with a magnetic layer coating. This enhancement of the MR effect can be explained as a result of the better transmission of forces to the working plate, in agreement with previous works [12,17]. On the other hand, the N-like shape was not so significant in the absence of applied magnetic field (Figure 5a).…”

Section: B N-like Shaped Rheogramssupporting

confidence: 92%

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N-like rheograms of concentrated suspensions of magnetic particles

López–López¹,

Rodríguez‐Arco²,

Zubarev³

et al. 2016

Journal of Rheology

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International audienceWe investigate the rheograms of concentrated suspensions of magnetic particles obtained under imposed shear rate in parallel plate geometry. We show that under magnetic field application the usual trend of the rheogram, i.e., increasing shear stress for the whole range of shear rates, is altered by the appearance of a region in which the shear stress decreases as the shear rate is increased. The existence of this region gives to the rheograms an N-like shape. The two initial regions (pre-yield regime) of these N-like rheograms present unstable flow, characterized by the oscillation of the shear stress with time for each imposed value of shear rate. We also show that rheograms obtained at different sample thicknesses approximately overlap in the developed flow regime, whereas there is a tendency of the shear stress to increase as the thickness is decreased in the pre-yield regime. This tendency is likely due to the strengthening of preexisting particle structures by compression as the gap thickness is decreased. Finally, we analyze the effect of the applied magnetic field strength, H, and demonstrate that the rheograms 2 scale with H 1.5 to a single master curve, for the range of applied magnetic fields under study

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Section: B N-like Shaped Rheogramssupporting

confidence: 92%

“…Haake [12]. For this aim we glued a layer of Fe-CC particles to each of the working surfaces of the set of parallel plates.…”

Section: (I)mentioning

confidence: 99%

N-like rheograms of concentrated suspensions of magnetic particles

López–López¹,

Rodríguez‐Arco²,

Zubarev³

et al. 2016

Journal of Rheology

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“…9 Chain or column structures are the key phenomena in MR effects, 10,11 and the shear stress of MR fluids comprises the magnetic, friction, and viscous forces of the base oil. [12][13][14] However, the insufficient understanding of MR effects impedes the potential applications of MR fluids. In fact, some interesting phenomena have been observed in MR fluids.…”

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confidence: 99%

Unexpected shear strength change in magnetorheological fluids

et al. 2014

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Smart materials of magnetorheological (MR) fluids could be turned from a liquid state into a solid state, which solidification extent or shear strength often increases monotonically with the applied magnetic field. In this study, the shear stress of a dilute MR fluid decreased with increasing applied magnetic field at a constant shear rate. The dynamic shear stress was significantly higher than the stable counterpart at medium magnetic fields. They are ascribed to the slow particle structure transformation. A higher shear rate and particle volume fraction could reduce the transient time and the shear strength difference.

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“…All features and parameters of this device have been analysed thoroughly by Laun et al (2010Laun et al ( ), (2011Laun et al ( ), (2008. A dual thermometer RS-1314 with a K-type thermocouple and an uncertainty of 0.8 K has been used to measure 500 nm …”

Section: Characterizationmentioning

confidence: 99%

Magnetorheological behaviour of propylene glycol-based hematite nanofluids

et al. 2015

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The study of nanofluids represents an innovative research area with remarkable development. Properties of ferric magnetic nanofluids, also denoted as ferrofluids, under the influence of an external magnetic field have attracted increasing attention. A set-up for performing rheological and magnetorheological tests of propylene glycol-based hematite (α-Fe 2 0 3 ) nanofluids is presented. The nanoparticle concentration dependence of the magnetorheological properties of this nanofluid was analysed at 303.15 K, ranging from 0.2 to 6.18 vol%, while external magnetic fields up to 0.7 T were applied. The rheological and magnetorheological experiments were performed using a rotational Physica MCR 101 rheometer, (Anton Paar), which is equipped with a magnetorheological device (MRD 170/1T) to control the magnetic flux density. A detailed study about the thixotropic behaviour of the samples as well as viscosity curves of magnetization and demagnetization responses, an analysis of the fractal dimension of the aggregates and conclusions about the magnetic field effect on the size of formed aggregates as a function of concentration has been developed in this work. Rheological tests show that the nanofluid studied presents non-Newtonian shear thinning, thixotropic and viscoelastic behaviour. Finally, the magnetic saturation of the material has been studied.

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Wall material and roughness effects on transmittable shear stresses of magnetorheological fluids in plate–plate magnetorheometry

Cited by 35 publications

References 13 publications

N-like rheograms of concentrated suspensions of magnetic particles

N-like rheograms of concentrated suspensions of magnetic particles

Unexpected shear strength change in magnetorheological fluids

Magnetorheological behaviour of propylene glycol-based hematite nanofluids

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