Experimental and numerical studies of squeeze mode behaviour of magnetic fluid

Magneto-rheological (MR) fluids are suspensions of micron-sized ferromagnetic particles in a non-magnetic carrier fluid. The essential characteristic of MR fluid is the rapid and reversible transition from the state of a Newtonian-like fluid to the behaviour of a stiff semi-solid by applying a magnetic field of ∼0.1–0.4 T. This feature can be understood from the fact that the particles form chain-like structures aligned in the field direction. The MR fluid offers three modes of operation, namely the direct shear mode, the valve mode, and the squeeze mode. The latter is of particular interest due to its highly non-linear behaviour, which is still not fully understood and therefore expected to give rise to new industrial applications. A test rig for the exploration of the MR-fluid behaviour was designed for experimental purposes. The present article describes the results of measurements under sinusoidal loading modes. Special emphasis was posed on the dependence of the MR-fluid response with respect to parameter variations of the applied static magnetic field, the cyclic loading amplitude, and frequency values. Cavitation effects have been investigated and partially suppressed by pre-pressurizing the MR fluid, which enables a more thorough insight into particle chain disruption and segregation effects. Well-pronounced hysteresis loops are observed and exhibit characteristic kinks, which cannot be understood within the frame of elementary constitutive laws such as for Bingham fluids. To describe the squeeze mode phenomenon numerically, adequate constitutive laws were applied, checked numerically by utilizing finite-element simulations, and validated against experimental data. New perceptions attained so far provided reason to design an adaptive MR-fluid bearing in squeeze mode behaviour for industrial applications.

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Magnetorheological Fluids Behaviour in Tension Loading Mode

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.47-50.242 ◽

2008 ◽

Vol 47-50 ◽

pp. 242-245 ◽

Cited By ~ 5

Author(s):

Saiful Amri Mazlan ◽

Ahmed Issa ◽

Abdul Ghani Olabi

Keyword(s):

Magnetic Field ◽

Tensile Stress ◽

Magnetic Particles ◽

Electrical Current ◽

High Ratio ◽

Solid Particles ◽

Mr Fluid ◽

Carrier Fluid ◽

Mr Fluids ◽

Water Based

In this paper, the behaviours of three types of MR fluids under quasi-static loadings in tension mode were investigated. One type of water-based and two types of hydrocarbon-based MR fluids were activated by a magnetic field generated by a coil using a constant value of DC electrical current. Experimental results in terms of stress-strain relationships showed that the MR fluids had distinct unique behaviours during the tension process. A high ratio of solid particles to carrier liquid in the MR fluid is an indication of high magnetic properties. The water-based MR fluid had a relatively large solid-to-liquid ratio. At a given applied current, a significant increase in tensile stress was obtained in this fluid type. On the other hand, the hydrocarbon-based MR fluids had relatively lower solid to liquid ratios, whereby, less increases in tensile stress were obtained. The behaviours of MR fluids were dependent on the relative movement between the solid magnetic particles and the carrier fluid. A complication occurs because, in the presence of a magnetic field, there will be a tendency of the carrier fluid to stick with the magnetic particle

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Modeling of Magnetorheological Fluids by the Discrete Element Method

Journal of Tribology ◽

10.1115/1.4006021 ◽

2012 ◽

Vol 134 (3) ◽

Cited By ~ 8

Author(s):

Mickaël Kargulewicz ◽

Ivan Iordanoff ◽

Victor Marrero ◽

John Tichy

Keyword(s):

Magnetic Field ◽

External Magnetic Field ◽

Discrete Element Method ◽

Discrete Element ◽

Magnetic Interactions ◽

Time Interval ◽

Mr Fluid ◽

Carrier Fluid ◽

Mr Fluids ◽

Element Method

Magnetorheological (MR) fluids are fluids whose properties vary in response to an applied magnetic field. Such fluids are typically composed of microscopic iron particles (~1-20μm diameter, 20-40% by volume) suspended in a carrier fluid such as mineral oil or water. MR fluids are increasingly proposed for use in various mechanical system applications, many of which fall in the domain of tribology, such as smart dampers and clutches, prosthetic articulations, and controllable polishing fluids. The goal of this study is to present an overview of the topic to the tribology audience, and to develop an MR fluid model from the microscopic point of view using the discrete element method (DEM), with a long range objective to better optimize and understand MR fluid behavior in such tribological applications. As in most DEM studies, inter-particle forces are determined by a force-displacement law and trajectories are calculated using Newton’s second law. In this study, particle magnetization and magnetic interactions between particles have been added to the discrete element code. The global behavior of the MR fluid can be analyzed by examining the time evolution of the ensemble of particles. Microscopically, the known behavior is observed: particles align themselves with the external magnetic field. Macroscopically, averaging over a number of particles and a significant time interval, effective viscosity increases significantly when an external magnetic field is applied. These preliminary results would appear to establish that the DEM is a promising method to study MR fluids at the microscopic and macroscopic scales as an aid to tribological design.

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Study of the Vibration Control of a Rotor System Using a Magnetorheological Fluid Damper

Journal of Vibration and Control ◽

10.1177/1077546305049481 ◽

2005 ◽

Vol 11 (2) ◽

pp. 263-276 ◽

Cited By ~ 16

Author(s):

J. Wang ◽

G. Meng

Keyword(s):

Magnetic Field ◽

Vibration Control ◽

Control Method ◽

Rotor System ◽

Shear Mode ◽

Rotor Vibration ◽

Mr Fluid ◽

Critical Speeds ◽

Fluid Damper ◽

Mr Fluid Damper

A shear mode magnetorheological (MR) fluid damper used for rotor vibration control is designed and manufactured, and the theoretical model of a cantilevered rotor system with the MR fluid damper is established. The response properties of the rotor system are studied theoretically and experimentally. It is found from the study that the Coulomb friction of the damper is increased as the magnetic field strength applied to the MR fluid increases. As a result, the vibration amplitude of the rotor system supported by the MR damper is decreased near the undamped critical speeds, but is increased in a rotating speed range between the first and the second undamped critical speeds. At the same time, the damped critical speed of the rotor system is increased with the increase of the applied magnetic field. Based on these characteristics, a simple on-off control method is used to suppress the rotor vibration across the critical speeds, and the results show that the method is very effective.

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Synthesis and Characterization of Magnetorheological Fluids

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.e2887.049620 ◽

2020 ◽

Vol 9 (6) ◽

pp. 272-277

Keyword(s):

Magnetic Field ◽

Three Dimensional ◽

Temperature Stability ◽

High Strength ◽

Industrial Applications ◽

Magnetorheological Fluids ◽

Carrier Fluid ◽

Performance Requirements ◽

Mr Fluids ◽

Mr Effect

Magnetorheological fluids (MRF) are mixture of ferromagnetic micron sized particles in silicon or hydraulic oil carrier fluid. By application of external varying strength magnetic field various physical properties of these fluids can be controlled and they becomes semi-solids depending on magnetic field strength application.MR fluids fulfill the desired performance requirements i.e. on application of magnetic field exhibits high shear and low initial viscosity, quick response , low hysteresis, low power consumption and temperature stability These special properties of MR fluids made them suitable for many type of industrial applications including machining. Hence fluids can be very effectively used in magnetorheological finishing process (MRF) which has unique feature of finishing truncated and complicated geometrical shapes and surfaces and capable of producing surface in nanometers. As surface finish is an important parameter in precision fits, product quality, and high-strength applications. The three dimensional surfaces finishing works such as different angled deep pockets or projections. Many industries have this type of i.e. mould & dies manufacturing, automobiles manufacturing, aerospace industry, semiconductor machining and optics machining etc. Such application leads to enhanced demand of nano-finishing of 3D surfaces without damaging surfaces/sub-surfaces. As due to change in properties because of change in composition the MR effect is also influenced. Therefore the composition of MR fluids is very important to achieve desired MR effect. The composition of magnetorheological fluids can be evaluated with the help of characterizations and desire MR fluid can be synthesized according to requirements of the process. This paper will explain in detail how we can synthesize and characterize the Magnetorheological fluids using state of the art equipments and can optimize their performance.

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Investigation of ultrasonic properties of MR fluid under various sweep rates of magnetic field

Magnetohydrodynamics ◽

10.22364/mhd.49.3-4.34 ◽

2013 ◽

Vol 49 (3-4) ◽

pp. 430-433

Author(s):

A. Isnikurniawan ◽

Y. Fujita ◽

S. Tanimoto ◽

T. Sawada

Keyword(s):

Magnetic Field ◽

Mr Fluid ◽

Ultrasonic Properties

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Magnetoviscosity of a Magnetic Fluid Based on Barium Hexaferrite Nanoplates

Materials ◽

10.3390/ma14081870 ◽

2021 ◽

Vol 14 (8) ◽

pp. 1870

Author(s):

Dmitry Borin ◽

Robert Müller ◽

Stefan Odenbach

Keyword(s):

Magnetic Field ◽

Experimental Study ◽

Magnetic Nanoparticles ◽

External Magnetic Field ◽

Shear Flow ◽

Magnetic Fluid ◽

Barium Hexaferrite ◽

Dipole Interaction ◽

Field Dependent ◽

Fluid Behaviour

This paper presents the results of an experimental study of the influence of an external magnetic field on the shear flow behaviour of a magnetic fluid based on barium hexaferrite nanoplates. With the use of rheometry, the magnetoviscosity and field-dependent yield-stress in the fluid are evaluated. The observed fluid behaviour is compared to that of ferrofluids with magnetic nanoparticles having high dipole interaction. The results obtained supplement the so-far poorly studied topic of the influence of magnetic nanoparticles’ shape on magnetoviscous effects. It is concluded that the parameter determining the observed magnetoviscous effects in the fluid under study is the ratio V2/l3, where V is the volume of the nanoparticle and l is the size of the nanoparticle in the direction corresponding to its orientation in the externally applied magnetic field.

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Design, Analysis and Test of a Hyperbolic Magnetic Field Voice Coil Actuator for Magnetic Levitation Fine Positioning Stage

Energies ◽

10.3390/en12101830 ◽

2019 ◽

Vol 12 (10) ◽

pp. 1830

Author(s):

Yiheng Zhou ◽

Baoquan Kou ◽

He Zhang ◽

Lu Zhang ◽

Likun Wang

Keyword(s):

Magnetic Field ◽

High Precision ◽

Magnetic Levitation ◽

Structural Parameters ◽

Industrial Applications ◽

Degree Of Freedom ◽

Force Density ◽

Precision Positioning ◽

Element Analysis ◽

Voice Coil Actuator

The multi-degree-of-freedom high-precision positioning system (MHPS) is one of the key technologies in many advanced industrial applications. In this paper, a novel hyperbolic magnetic field voice coil actuator using a rhombus magnet array (HMF-VCA) for MHPS is proposed. Benefiting from the especially designed rhombus magnet array, the proposed HMF-VCA has the advantage of excellent force uniformity, which makes it suitable for multi-degree-of-freedom high-precision positioning applications. First, the basic structure and operation principles of the HMF-VCA are presented. Second, the six-degree-of-freedom force and torque characteristic of the HMF-VCA is studied by three-dimensional finite element analysis (3-D FEA). Third, the influence of structural parameters on force density and force uniformity is investigated, which is conducive to the design and optimization of the HMF-VCA. Finally, a prototype is constructed, and the comparison between the HMF-VCA and conventional VCAs proves the advantage of the proposed topology.

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Effects of T5 and T6 Heat Treatments Applied to Rheocast A356 Parts for Automotive Applications

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.141-143.237 ◽

2008 ◽

Vol 141-143 ◽

pp. 237-242 ◽

Cited By ~ 16

Author(s):

Mario Rosso ◽

Ildiko Peter ◽

R. Villa

Keyword(s):

Fatigue Behaviour ◽

Cyclic Stress ◽

Industrial Applications ◽

Fatigue Tests ◽

Controlled Cooling ◽

Test Analysis ◽

Heat Treated ◽

Mechanical Performances ◽

Semi Solid ◽

Number Of Cycles

The correlation between the evaluation of the mechanical and of the fatigue behaviour of the rheocast, T5 and T6 heat treated SSM A356 aluminium alloy with respect to the microstructures of the component has been investigated. The study has been carried out on a suspension arm injected in a rheocasting 800 tons plant in Stampal S.p.A. The new rheocasting is a process that allows obtaining the alloys in a semisolid state directly from the liquid state, by controlled cooling of the molten alloys. The resulting microstructures are very fine, free from defects and homogeneous: these characteristics improve the mechanical properties of the alloys and specially the response to cyclic stress, an important issue for a suspension component. After a preliminary tensile test analysis, axial high frequency fatigue tests have been carried out at room temperature on specimen cut out from the suspension arm to determine the Wöhler curve and the number of cycles to failure. The results of this work allow a comparison of the effects of heat treatment process, T5 or T6, on Semi-Solid components for industrial applications in the automotive field. On the basis of these analysis the correlation between microstructure and mechanical performances can be established.

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Study on the Unbalanced Curl Seal Failure of the Magnetorheological Fluid Sealing Device of the Hydraulic Turbine Main Shaft under Different Speed Abrupt Conditions

Processes ◽

10.3390/pr9071171 ◽

2021 ◽

Vol 9 (7) ◽

pp. 1171

Author(s):

Jie Cheng ◽

Zheng-Gui Li ◽

Yang Xu ◽

Wang-Xu Li ◽

Xin-Rui Li

Keyword(s):

Magnetic Field ◽

Sudden Change ◽

Hydraulic Turbine ◽

Frictional Heat ◽

Main Shaft ◽

Mr Fluid ◽

Friction Heat ◽

Sealing Ability ◽

Sealing Failure ◽

Sealing Device

The fluid flow in the runner of a hydraulic turbine has serious uncertainties. The sealing failure of the magnetorheological (MR) fluid sealing device of the main shaft of the hydroturbine, caused by a sudden change in speed, has always been a difficult topic to research. This study first derives the MR fluid seal pressure and unbalanced curl equations of the hydroturbine main shaft, and then analyzes the seal pressure and friction heat under different rotational speed mutation conditions through experiments. After verification, the temperature field and magnetic field distribution of the MR fluid sealing device of the main shaft of the hydraulic turbine are obtained via numerical calculation. The results show that the external magnetic field affects the magnetic moment of the magnetic particles in the MR fluid, resulting in a significant change in frictional heat, thereby reducing the saturation of magnetic induction intensity of the MR fluid. This results in a decrease in the sealing ability of the device. The size and abrupt amplitude of the main shaft of the hydraulic turbine, and friction heat is positively correlated reducing the sealing ability of the device and causing sealing failure. Based on our results, we recommend adding the necessary cooling to the device to reduce the frictional heat, thereby increasing the seal life of the device.

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