• Title/Summary/Keyword: magnetorheological suspensions

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Behaviour of field-responsive suspensions under oscillatory shear flow

  • Keentok, Matti;See, Howard
    • Korea-Australia Rheology Journal
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    • v.19 no.3
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    • pp.117-123
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    • 2007
  • There has been considerable interest in recent years in field-responsive suspensions, which are of some importance in industry in many different applications. The microstructure of these materials is a significant issue which can be probed by rheological measurements. In this study, measurements were made of a magnetorheological fluid (MRF) under steady and oscillatory shear flow, with and without a magnetic field. Mathematical inversion was used to derive the relaxation time spectrum of the MRF from oscillatory shear data. Experimental evidence is presented of the gel-like properties of this MRF.

Magnetic-field-tuned Insulator to Conductor Transition in Magnetorheological Suspension

  • Yang, Xiongbo;Jiang, Yuhuan;Huang, Yuehua;Xu, Ruizhen;Piao, Hongguang;Jia, Gaomeng;Tan, Xinyu
    • Journal of Magnetics
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    • v.19 no.4
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    • pp.345-348
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    • 2014
  • Magnetorheological suspensions (MRSs) are smart materials that have the potential to revolutionize several industrial sectors because of their special rheological behaviors. In this paper, MRS, based on carbonyl iron (CI) microparticles that were dispersed in silicone oil with oleic acid, were prepared. We showed that the electroconductibility of MRS was significantly influenced by the intensity of the external magnetic field that was applied. The resistance value can vary from infinite to below $300{\Omega}$ after applying an external magnetic field. The results indicated that this MRS had the property of magnetic-field-tuned insulator to conductor transition. This system has potential applications in controllable MRS electrical devices.

Influence of Oleic and Lauric Acid on the Stability of Magnetorheological Fluids

  • Huang, Yuehua;Jiang, Yuhuan;Yang, Xiongbo;Xu, Ruizhen
    • Journal of Magnetics
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    • v.20 no.3
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    • pp.317-321
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    • 2015
  • In this paper, magnetorheological fluids (MRFs) based on micro-sized iron particles dispersed in silicone oil are presented. The iron particles are modified by adding different ratios of oleic acid and lauric acid as surfactants to the suspensions. Lauric acid was found to reduce the stability of the MRFs, and more lauric acid results in a higher rate of sedimentation. Further study showed that the formation and structure of lauric acid may result in the sedimentation of micrometer-sized particles. Meanwhile, the electro-resistance of MRF in this paper shows a decrease from beyond $6000M{\Omega}$ to $190{\Omega}$ with an increase in the external field from 0 mT to 400 mT.