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2 2009

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Magnetorheological characterisation of carbonyl iron based suspension

Kciuk M., Kciuk S., Turczyn R.

Journal of Achievements in Materials and Manufacturing Engineering

2009

Vol. 33, nr 2

135-141

Purpose: The main aim of this article was to present the investigation results of magnetorheological fluids (MR) composed of carbonyl iron (CI) particles and analyse their flow behaviour in terms of the internal structure formation by a control of applied external magnetic field. The morphology, magnetic properties, sedimentation stability, and magnetorheological properties of the examined MR fluids were studied. Design/methodology/approach: Model MR fluid was prepared using silicone oil OKS 1050 mixed with carbonyl iron powder CI. Furthermore, to reduce sedimentation Aerosil 200 was added as stabilizers. In the purpose to determine the properties of the analyzed fluids the sedimentation and dynamic viscosity were investigated. Findings: Dynamic viscosity of investigated magnetorheological fluids rapidly and reversibly change in response to the applied external magnetic field. Moreover added particles of fumed silica inhibited sedimentation of carbonyl iron particles. Research limitations/implications: MR fluids with excellent properties can be applied in various fields of civil engineering, safety engineering, transportation and life science. They offer an outstanding capability of active control of mechanical properties. But there are no systematic published studies of factors affecting the durability of MR fluids and devices. There is very little information on the effects of exposing different MR fluids to temperature, for this reasons further efforts are needed in order to obtain even better results. Originality/value: The investigation results are reliable and could be very useful both for designers and the practitioners of many branches of industry.

Wpływ mikrostruktury na właściwości magnetoreologicznych elastomerów

Boczkowska A., Awietjan S.

Czasopismo Techniczne. Mechanika

2009

R. 106, z. 1-M

31-36

Magnetoreologiczne elastomery (MREs) zawierające cząstki żelaza karbonylowego w osnowie poliuretanowej były wytwarzana i badane. Dzięki charakterystycznej mikrostrukturze kolumnowej MREs odpowiadają na działanie pola magnetycznego poprzez zmianę właściwości reologicznych. Zbadano próbki o różnym ułożeniu łańcuchów cząstek względem linii pola magnetycznego zastosowanego podczas pomiarów. Wytwarzano także próbki o izotropowym rozmieszczenie cząstek. Stwierdzono, że ukierunkowanie łańcuchów cząstek względem pola magnetycznego ma istotny wpływ na właściwości reologiczne MREs w polu magnetycznym. Moduł sprężystości postaciowej (G') silnie zależy od mikrostruktury MREs, a w szczególności od ułożenia cząstek. Uzyskane krzywe G'([omega]) były aproksymowane równaniem zgodnym z modelem Cassona. Uzyskano i porównano wartości naprężenia uplastyczniającego [tau]0 dla różnych MREs.

In this work urethane magnetorheological elastomers (MREs) consisting of carbonyl-iron particles and a polyurethane matrix were manufactured and studied. Due to the characteristic columnar microstructure, MREs respond to the magnetic field by changing their rheological properties. The samples with different arrangement of particle chains relative to the magnetic field lines during measurement were studied. Also samples with the isotropic particles distribution were fabricated. The significant influence of the ferromagnetic particles arrangement on the rheological properties of the MREs in the relation to an external magnetic field was found. Storage modulus (G') strongly depend on the MREs microstructure, in particular on particles arrangement. Measured G'([omega]) curves were approximated with Casson's model. According to the approximation values of yield stress [tau]0 for different MREs were compared.