Rheological properties of a model colloidal suspension under large electric fields of different waveforms

Espin, M. J.; Delgado, A.V.; González‐Caballero, F.; Rejón, L.

doi:10.1016/j.jnnfm.2007.01.007

Cited by 7 publications

(6 citation statements)

References 45 publications

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“…There is no point at which sine could be used to achieve a higher pressure drop. The effect that AC square shows a superior performance has also been observed by Bauerochs et al (2018) and Espin et al (2007).…”

Section: Resultssupporting

confidence: 56%

“…Yield stress investigation on microchannels with fluids of different particle volume fractions was performed by Helal et al (2016). Chen and Luckham (1993), Ginder and Ceccio (1995), 1 Ma et al (1996), Misono et al (2004) and Espin et al (2007) described the alternating current (AC) response of ER-Fluids and showed a dependence on the electric frequency. This manifests itself in such a way that a decreasing pressure drop occurs with a frequency increase.…”

Section: Introductionmentioning

confidence: 99%

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Alternating current response and visualization of electrorheological fluid

Bauerochs

Huo

Yossifon

et al. 2019

Journal of Intelligent Material Systems and Structures

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The electrorheological effect produced by an ER-Fluid with an applied electric field is not yet fully understood. However, it is significant to understand how the viscosity increases, and thus, the ER-Effect works to optimally design ER-Applications. In this article, the ER-Effect and its response to different voltage forms with varying frequencies within a miniature fluidic device are described and visualized using a microscope. The different pressure drops across the channel are measured. Problems such as long saturation times using microchannels in combination with low flow velocities are described and explained. An electric frequency dependence of the chain formation has been discovered and that the use of alternating current offers superior performance in comparison with direct current. The optimal operating point for achieving the largest possible pressure difference is from 5 to 10 Hz for square wave voltages. In this frequency range, the performance of the electrorheological effect is greater than using direct current. From approximately 10 Hz, the power decreases with increasing electric frequency. Above 20 Hz, direct current is superior to alternating current voltage, so is not recommended for use in this range.

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Section: Resultssupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Alternating current response and visualization of electrorheological fluid

Bauerochs

Huo

Yossifon

et al. 2019

Journal of Intelligent Material Systems and Structures

View full text Add to dashboard Cite

show abstract

“…Experimental results obtained using a rheometer are different from the results gained in flow channel experiments (Freyer et al, 2015). The rheological properties of a model colloidal suspension under large electric fields of different waveforms were well studied (Espin et al, 2007). But the effects of different external electric fields on the pressure drops of ER valve are still absent.…”

Section: Introductionmentioning

confidence: 99%

A test of giant electrorheological valve in DC and square wave AC fields with different frequencies

Han

et al. 2017

Journal of Intelligent Material Systems and Structures

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The high price and less content of current Braille displays keep most of visually impaired persons from using them. The compact arrangement of Braille dots regulated by Braille standard presents a rigid limitation to develop a full-page Braille display. Electrorheological valve gives a possibility to meet these severe demands, and its pressure drop is a key parameter to design a full-page Braille display. A giant electrorheological valve in DC field and square waveform AC field with different frequencies was investigated. It was shown that the pressure drop of valve increases with the electric field strength, and decreases with increasing frequency of square waveform AC field. The pressure drop of the giant electrorheological valve is high enough for the purpose in application of a full-page Braille display. The results also show that only square waveform AC field with low frequency can provide higher pressure drops. A forcing flow of giant electrorheological fluids in channel of valve may be a solution of solving the aggregations of nanoparticles on the electrodes.

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“…ER fluids usually show a liquid (close to Newtonian) behavior in the absence of the field, while becoming viscoelastic (or even solid-like) materials, with a significant yield stress and elastic modulus, under the application of an external electric excitation. Understanding the mechanisms by which such changes take place is an interesting and difficult challenge since the ER response is controlled not only by the magnitude and characteristics of the applied field [4] but also by a wide range of properties of the system itself. For ER fluids consisting of particles dispersed in a fluid (heterogeneous ER fluids), this effect is controlled by a number of parameters, including the volume fraction of solids, the electrical conductivities and permittivities of the solid and liquid phases, the particle size and shape and the contents of water and other additives in the samples [1,5,6].…”

Section: Introductionmentioning

confidence: 99%