Dynamic Viscoelasticity of a Magnetorheological Fluid in Oscillatory Slit Flow

The nonlinear dynamic viscoelasticity of an MR fluid in oscillatory slit flow under magnetic flux normal to the flow has been investigated by using a newly developed oscillatory pressure flow type rheometer. An MR fluid consisting of micron-sized, magnetically polarizable particles dispersed into a carrier medium is evaluated. The dynamic viscoelasticity remarkably depends on a fluid strain amplitude and a magnetic field strength. Both of the storage modulus (G′) and loss modulus (G″) increase dramatically with the increase of applied magnetic field strength H from 0 to 160 kA/m. And for the increase of the strain amplitude, both of them dramatically decrease, while the loss tangent ( tan δ) increases remarkably, showing the dominance of viscoelastic plastic property. The above results are discussed in terms of three deformation regions of the MR fluid; pre-yield, yield, post-yield.

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Dynamic Viscoelasticity in Oscillatory Slit Flow of an ER Suspension Containing Sulfonated Polymer Particles

International Journal of Modern Physics B ◽

10.1142/s0217979299001909 ◽

1999 ◽

Vol 13 (14n16) ◽

pp. 1870-1877 ◽

Cited By ~ 2

Author(s):

Masami Nakano ◽

Kouya Ito ◽

Makoto Konno ◽

Ryuji Aizawa

Keyword(s):

Shear Flow ◽

Field Strength ◽

Strain Amplitude ◽

Applied Field ◽

Plastic Property ◽

Oscillatory Shear ◽

Polymer Particles ◽

Dynamic Viscoelasticity ◽

Oscillatory Shear Flow ◽

Slit Flow

An oscillatory slit flow type rheometer has been developed to measure the dynamic viscoelasticity in an oscillatory slit flow of an ER fluid. Using the rheometer, an ER suspension of numerously sulfonated polymer particles in an insulating oil is evaluated. The results are compared with those for the oscillatory shear flow. In the slit flow, the dynamic viscoelasticity of the ER suspension mainly depends on the fluid strain amplitude and the applied electric field strength. In the fluid strain amplitude of less than about 50% the viscoelastic property becomes dominant, while in the fluid strain amplitude of more than that the viscoelastic plastic property dominates. As the applied field strength increases, the dynamic viscoelasticity changes from viscoelastic plastic to linear viscoelastic. In an oscillatory shear flow, on the other hand, the dynamic viscoelasticity of the ER suspension largely depends on the fluid strain and hardly on the applied field strength. The differences between the dynamic viscoelasticity in the two flow modes can be explained based on the formation and deformation of ER particle clusters which span the electrodes.

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Measurements on the Temperature, Dynamic Strain Amplitude and Magnetic Field Strength Dependence of the Dynamic Shear Modulus of Magnetosensitive Elastomers in a Wide Frequency Range

Journal of Vibration and Acoustics ◽

10.1115/1.4025063 ◽

2013 ◽

Vol 135 (6) ◽

Cited By ~ 6

Author(s):

Jonas Lejon ◽

Leif Kari

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Shear Modulus ◽

Magnetic Field Strength ◽

Strain Amplitude ◽

Wide Frequency Range ◽

Dynamic Strain ◽

Dynamic Shear Modulus ◽

Frequency Range ◽

Temperature Dynamic

A measurement study is conducted to investigate how changes in temperature, dynamic strain amplitude, and magnetic field strength influence the behavior of a magnetosensitive material. During the measurements seven temperatures, four magnetic fields, and three dynamic strain amplitudes are used over a 200 to 800 Hz frequency range. The results indicate a decrease in shear modulus magnitude as the dynamic strain amplitude is increased. As the frequency and magnetic field strength increases the magnitude increases. However, the measurements indicate that the temperature is the most influential of the parameters as the material stiffens significantly when the temperature reaches the transition phase. Understanding the temperature dependence increases the knowledge of magnetosensitive materials.

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Selection of Materials in Designing Magnetorheological Brake

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.663.700 ◽

2014 ◽

Vol 663 ◽

pp. 700-704

Author(s):

Lailatul Hamidah Hamdan ◽

Saiful Amri Mazlan ◽

Shamsul Sarip ◽

Hairi Zamzuri ◽

Mohd Azizi Abdul Rahman

Keyword(s):

Magnetic Field ◽

Magnetic Material ◽

Field Strength ◽

Magnetic Field Strength ◽

Advanced Technology ◽

Brake Disc ◽

Finite Elements Analysis ◽

Mr Fluid ◽

The Magnetic Field ◽

Selection Of

The braking system is among the most significant active safety systems in a vehicle application for preventing injuries and property damage. Whether for light or heavy vehicles, brakes are no longer a small issue whereas it becomes a crucial problem to maintain the safety and to avoid the unpredictable cases especially on the road. Advanced technology in automotive industry has produced a new coming design of Magnetorheological (MR) brake which a field change is triggered off by changing the current in the coils exciting the magnetic field. MR fluid is one of the members of smart material which applicable usage to achieve the standard of rotary high speed similar as the existing brake disc in hydraulic system. A new MR brake disc was proposed using the squeeze mode rather than only conventional mode at the upper and lower rotating rotor. Parameters that have been considered are the types of MR fluid, selection of magnetic material, non-magnetic material and coil configurations. Then a finite elements analysis was performed to analyse the result of magnetic circuit and magnetic field strength within the MR brake configuration. MRF-140CG has been selected to represent the fluid to enhance the maximum magnetic flux density. The results showed that AISI 1020 and Stainless Steel 316 meet the requirement of material selection of magnetic and non-magnetic. Indirectly, yield stress has been significant increase when the magnetic field strength rises at certain value. Therefore, intention on design innovation of MR brake is useful to efficient control by upgrading function of those parameters which has been presented.

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Dynamic Properties of Squeeze Type Mount Using MR Fluid

Design Engineering, Volumes 1 and 2 ◽

10.1115/imece2003-55187 ◽

2003 ◽

Cited By ~ 1

Author(s):

Jong-Yong Ha ◽

Young Kong Ahn ◽

Bo-Suk Yang ◽

Dong-Jo Kim ◽

Mehdi Ahmadian

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Magnetic Field Strength ◽

Dynamic Properties ◽

Wide Frequency Range ◽

Mr Fluid ◽

Damping Characteristics ◽

Exciting Frequency ◽

Magneto Rheological ◽

Mr Effect

This paper presents an investigation of damping characteristics of a squeeze mode type MR (Magneto-Rheological) mount. Since the damping property of an MR fluid is changed by the variation of the applied magnetic field strength, the squeeze mode type MR mount proposed in this study has variable damping characteristics. In the present work, the performance of the mount was experimentally investigated according to the magnetic field strength and exciting frequency. The experimental results show that the MR mount can effectively reduce the vibration amplitude in a wide frequency range by controlling the field strength. Viscous damping and stiffness coefficients of the MR mount tend to be changed according to the variation of the applied currents in this study and MR effect is reduced by increasing exciting frequency.

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On the Configuration of the Magnetic Field of β CrB

International Astronomical Union Colloquium ◽

10.1017/s0252921100080933 ◽

1976 ◽

Vol 32 ◽

pp. 613-622

Author(s):

I.A. Aslanov ◽

Yu.S. Rustamov

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Radial Velocity ◽

Magnetic Field Strength ◽

Complex Shape ◽

Rotation Period ◽

Field Variation ◽

Magnetic Field Variation ◽

Secular Variations ◽

The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

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Suppress of neurotransduction in injured spinal cord of rats with moderate magnetic field strength

Neuroscience Research ◽

10.1016/s0168-0102(00)81259-6 ◽

2000 ◽

Vol 38 ◽

pp. S69

Author(s):

H Tatsuoka

Keyword(s):

Magnetic Field ◽

Spinal Cord ◽

Field Strength ◽

Magnetic Field Strength ◽

Injured Spinal Cord ◽

Moderate Magnetic Field

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2D analysis of magnetic field strength in GO SiFe steel sheets

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:19982133 ◽

1998 ◽

Vol 08 (PR2) ◽

pp. Pr2-579-Pr2-582 ◽

Cited By ~ 1

Author(s):

S. Tumanski ◽

M. Stabrowski

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Magnetic Field Strength ◽

Steel Sheets

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MAGNETIC FIELD, PRESSURE AND TEMPERATURE DEPENDENT OPTICAL PROPERTIES IN A GaAs 9.0 P 1.0 QUANTUM DOT

JOURNAL OF ADVANCES IN PHYSICS ◽

10.24297/jap.v6i2.1791 ◽

2014 ◽

Vol 6 (2) ◽

pp. 1178-1190

Author(s):

A. JOHN PETER ◽

Ada Vinolin

Keyword(s):

Magnetic Field ◽

Optical Properties ◽

Quantum Dot ◽

Field Strength ◽

Magnetic Field Strength ◽

Photon Energy ◽

Nonlinear Optical ◽

Binding Energies ◽

Nonlinear Optical Properties ◽

Optical Rectification

Simultaneous effects of magnetic field, pressure and temperature on the exciton binding energies are found in a 9.0 1.0 6.0 4.0 GaAs P / GaAs P quantum dot. Numerical calculations are carried out taking into consideration of spatial confinement effect. The cylindrical system is taken in the present problem with the strain effects. The electronic properties and the optical properties are found with the combined effects of magnetic field strength, hydrostatic pressure and temperature values. The exciton binding energies and the nonlinear optical properties are carried out taking into consideration of geometrical confinement and the external perturbations.Compact density approach is employed to obtain the nonlinear optical properties. The optical rectification coefficient is obtained with the photon energy in the presence of pressure, temperature and external magnetic field strength. Pressure and temperature dependence on nonlinear opticalÂ susceptibilities of generation of second and third order harmonics as a function of incident photon energy are brought out in the influence of magnetic field strength. The result shows that the electronic and nonlinear optical properties are significantly modified by the applications of external perturbations in a 9.0 1.0 6.0 4.0 GaAs P / GaAs P quantum dot.

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