• Title, Summary, Keyword: Magnetorheological Fluid

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Effect of Wall Groove Characteristics on Yield Stress Measurement of Magnetorheological Fluid

  • Tian, Zuzhi;Guo, Chuwen;Chen, Fei;Wu, Xiangfan
    • Journal of Magnetics
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    • v.22 no.2
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    • pp.281-285
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    • 2017
  • To suppress the wall slip effect and improve the yield stress measurement precision of magnetorheological fluid, measurement disks with different grooves are first manufactured. Then, the influence of groove characteristics on the yield stress of magnetorheological fluid is investigated by the method of experiments. Finally, the optimization wall grooves of measurement disks are obtained, and the yield stress of a self-prepared magnetorheological fluid is measured. Results indicate that the groove type and groove width have a slight influence on the shear yield stress, whereas the measured yield stress increases with enhanced groove density, and the optimized groove depth is 0.3 mm. The measured shear yield stress of self-prepared MR fluid can be improved by 18 % according to the optimized grooved disks, and the maximum yield stress can reach up to 65 kPa as the magnetic flux density is 0.5 T.

Conditioning of Magnetorheological finishing (자성유변연마의 컨디셔닝 기술)

  • 신영재;이응숙;김경웅;김영민
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.557-560
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    • 2003
  • Magnetorheological finishing(MRF) is a newly developed and recently commercialized for finishing optical components. The magnetorheological fluid consists of a water based suspension of carbonyl iron, nonmagnetic polishing abrasives, and small amounts of stabilizer. This magnetorheological fluid is pumped from conditioner on the rotating wheel and suctioned back to the conditioner, where it cooled to setpoint temperature and evaporative losses are replaced. This method could produce some problems in suction. So newly designed MRF tools is proposed in which MR fluid is not circulated and conditioned by the slurry. The new polishing mechanism is experimented. Measured surface roughness supports the validity of this mechanism.

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Study on the Preparation Process and Properties of Magnetorheological Fluid Treated by Compounding Surfactants

  • Wu, Xiangfan;Xiao, Xingming;Tian, Zuzhi;Chen, Fei
    • Journal of Magnetics
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    • v.21 no.2
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    • pp.229-234
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    • 2016
  • Aiming to prepare high performance magnetorheological fluid, firstly, oleic acid and sodium dodecyl benzene sulfonate are chosen as surfactants. And then, the mechanical stirring process including stirring time, stirring temperature and stirring speed are optimized by measuring sedimentation ratio and zero-field viscosity. Finally, the properties of prepared magnetorheological fluid are elaborated. The results indicate that the compounding of oleic acid and sodium dodecyl benzene sulfonate can improve the properties of magnetorheological fluid distinctively, and the optimistic compounding content is 4g:4g or 5g:5g. The surfactants adding orders and the second stirring time have little effect on the properties of magnetorheological fluid, while obviously of the first stirring time, temperature and speed. Moreover, the sedimentation ratio of prepared magnetorheological fluid is less than 5.2% in two weeks, the zero-field viscosity is smaller than $0.6Pa{\cdot}s$ at $20^{\circ}C$, and the maximum yield stress is higher than 50 kPa.

Magnetorheological Finishing (자성유체를 이용한 연마)

  • 신영재;이응숙;황경현;김경웅
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.775-778
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    • 2000
  • Magnetorheological Finishing(MRF) is a newly developed and recently commercialized for finishing optical components. The magnetorheological fluid consists of a water based suspension of carbonyl iron, nonmagnetic polishing abrasives, and small amounts of stabilizer. Theoretical analysis of MRF, based on Bingham lubrication theory, is illustrated and a correlation between surface shear stress on the workpiece and material removal is obtained.

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Magnetorheological fluids subjected to tension, compression, and oscillatory squeeze input

  • El Wahed, Ali K.;Balkhoyor, Loaie B.
    • Smart Structures and Systems
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    • v.16 no.5
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    • pp.961-980
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    • 2015
  • Magnetorheological (MR) fluids are capable of changing their rheological properties under the application of external fields. When MR fluids operate in the so-called squeeze mode, in which displacement levels are limited to a few millimetres but there are large forces, they have many potential applications in vibration isolation. This paper presents an experimental and a numerical investigation of the performance of an MR fluid under tensile and compressive loads and oscillatory squeeze-flow. The performance of the fluid was found to depend dramatically on the strain direction. The shape of the stress-strain hysteresis loops was affected by the strength of the applied field, particularly when the fluid was under tensile loading. In addition, the yield force of the fluid under the oscillatory squeeze-flow mode changed almost linearly with the applied electric or magnetic field. Finally, in order to shed further light on the mechanism of the MR fluid under squeeze operation, computational fluid dynamics analyses of non-Newtonian fluid behaviour using the Bingham-plastic model were carried out. The results confirmed superior fluid performance under compressive inputs.

A Study on the Effect of the Material and Applied Magnetic Field Strength on the Friction Characteristics of Magnetorheological Fluids (재질과 자기장 세기가 자기유변유체의 마찰 특성에 미치는 영향)

  • Zhang, Peng;Lee, Kwang-Hee;Lee, Chul-Hee
    • Tribology and Lubricants
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    • v.29 no.1
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    • pp.39-45
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    • 2013
  • Magnetorheological (MR) fluid belongs to the group of smart materials. In MR fluid, iron particles in base oil form chains in the direction of the applied magnetic field, thus resulting in a variation in the stiffness and damping characteristics of the fluid. Research is being carried out on controlling the stiffness and damping characteristics as well as the tribological characteristics of the MR fluid. In this study, the friction characteristics of MR fluid have been evaluated using three types of materials and magnetic fields of different strengths. The coefficients of friction of the three types of MR fluid are measured, and the relationship between the coefficient of friction and the strength of the applied magnetic field is obtained.

Hysteresis Investigation of Magnetorheological Fluid Using Preisach Model (Preisach모델을 이용한 MR 유체의 히스테리시스 특성 고찰)

  • Han, Y.M.;Lim, K.H.;Choi, S.B.
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.1
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    • pp.3-11
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    • 2006
  • This paper presents a new approach for hysteresis modeling of a magnetorheological (MR) fluid. The field-dependent hysteresis of MR fluid is investigated using the Preisach model. The commercial MR product (MRF-132LD, Lord Corporation) is employed. Its field-dependent shear stress is then obtained using a rheometer (MCR 300, Physica). In order to show the applicability of the Preisach model to the MR fluid, two significant properties; the minor loop property and the wiping-out. property are experimentally examined. Subsequently, the Preisach model for the MR fluid is identified using experimental first order descending (FOD) curves in discrete manner. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one. In addition, the hysteresis model proposed in this work is compared to Bingham model.

Hysterisis Investigation of Magnetorheological Fluid Using Preisach Model (Preisach 모델을 이용한 MR 유체의 히스테리시스 특성 고찰)

  • Han, Y.M.;Lim, K.H.;Choi, S.B.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.350-355
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    • 2005
  • This paper presents a new approach for hysteresis modeling of a magnetorheological (MR) fluid. The field-dependent hysteresis of MR fluid is investigated using the Preisach model. The commercial MR Product (MRF-132LD, Lord Corporation) is employed. Its field-dependent shear stress is then obtained using a rheometer (MCR 300, Physica). In order to show the applicability of the Preisach model to the MR fluid, two significant Properties; the minor loop property and the wiping-out property are experimentally examined. Subsequently, the Preisach model for the MR fluid is identified using experimental first order descending (FOD) curves in discrete manner. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one. In addition, the hysteresis model proposed in this work is compared to Bingham model.

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Effect of Particle Characteristics and Temperature on Shear Yield Stress of Magnetorheological Fluid

  • Wu, Xiangfan;Xiao, Xingming;Tian, Zuzhi;Chen, Fei;Jian, Wang
    • Journal of Magnetics
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    • v.21 no.2
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    • pp.244-248
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    • 2016
  • Aiming to improve the shear yield stress of magnetorheological fluid, magnetorheological fluids with different particle characteristics are prepared, and the influence rules of particle mass fraction, particle size, nanoparticles content and application temperature on shear yield stress are investigated. Experimental results indicate that shear yield stress increases approximate linearly with the enhancement of particle mass fraction. Particle size and the nanoparticles within 10% mass fraction can improve the shear yield stress effectively. When the application temperature is higher than $100^{\circ}C$, the shear yield stress decreases rapidly because of thermal expansion and thermal magnetization effect.

The Principle of Magnetorheological finishing for a micro part (자성 유체를 이용한 미세연마가공의 원리)

  • 김동우;신영재;이응숙;조명우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.1840-1843
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    • 2003
  • The Magnetorheological fluid has the properties that its viscosity has drastic changed under some magnetic fields therefore, Magnetorheological fluids has been used for micro polishing of the micro part( for example, a aspherical surface in a micro lens). The polishing process may appears as follows. A part rotating on the spindle is brought into contact with an Magnetorheological finishing(MRF) fluids which is set in motion by the moving wall. In the region where the part and the MRF fluid ate brought into contact, the applied magnetic field creates the conditions necessary for the material removal from the part surface. The material removal takes place in a certain region contacting the surface of the part which can be called the polishing spot or zone. The polishing mechanism of the material removal in the contact zone is considered as a process governed by the particularities of the Bingham flow in the contact zone. Resonable calculated and experimental magnitudes of the material removal rate for glass polishing lends support the validity of the approach.

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