Platform Design for Characterizing Shear Force Produced by Magnetized Magnetorheological Fluid

2019 ◽  
Author(s):  
Ping-Hsun Lee ◽  
Jen-Yuan (James) Chang
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Yield Stress ◽  
Flux Density ◽  
Shear Force ◽  
Permanent Magnets ◽  
Magnetic Flux Density ◽  
Finite Element Method Result ◽  
Mr Fluid ◽  
The Magnetic Field

Abstract In this paper we proposed a platform for measuring shear force of magnetorheological (MR) fluid by which the relationship of yield stress and magnetic flux density of specific material can be determined. The device consisted of a rotatable center tube in a frame body and the magnetic field was provided by two blocks of permanent magnets placed oppositely outside the frame body. The magnitude and direction of the magnetic field were manipulated by changing the distance of the two permanent magnets from the frame body and rotating the center tube, respectively. For determining the magnetic field of the device, we adopted an effective method by fitting the FEM (finite element method) result to the measured one and then rebuilt the absent components to approximate the magnetic field, which was hardly to be measured simultaneously as different device setup were required. With the proposed platform and analytical methods, the drawing shear force and the corresponding yield stress contributed by MR fluid could be evaluated in respect to the magnitude and direction of given magnetic flux density with acceptable accuracy for specific designing purposes without a large, complex, and expensive instrument.

scholarly journals Design of a New 1D Halbach Magnet Array with Good Sinusoidal Magnetic Field by Analyzing the Curved Surface

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2522
Author(s):  
Guangdou Liu ◽  
Shiqin Hou ◽  
Xingping Xu ◽  
Wensheng Xiao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Permanent Magnet ◽  
Flux Density ◽  
Permanent Magnets ◽  
Air Gap ◽  
Curved Surface ◽  
Magnetic Flux Density ◽  
Sinusoidal Magnetic Field ◽  
The Magnetic Field

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.

Numerical study of magnetic circuit response in magneto-rheological damper

2016 ◽  
Vol 14 (1) ◽  
pp. 196-210 ◽  
Author(s):  
Mohammad Sadak Ali Khan ◽  
A. Suresh ◽  
N. Seetha Ramaiah
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Yield Stress ◽  
Flux Density ◽  
Magnetic Force ◽  
Mr Damper ◽  
Magnetic Flux Density ◽  
Piston Velocity ◽  
Mr Fluid ◽  
Content Type

Purpose – The purpose of this paper is to evaluate the performance of the semi-active fluid damper. It is recognized that the performance of such a damper depends upon the magnetic and hydraulic circuit design. These dampers are generally used to control the vibrations in various applications in machine tools and robots. The present paper deals with the design of magneto-rheological (MR) damper. A finite element model is built to analyze and understand the performance of a 2D axi-symmetric MR damper. Various configurations of damper with modified piston ends are investigated. The input current to the coil and the piston velocity are varied to evaluate the resulting change in magnetic flux density (B), magnetic field (H), field dependent yield stress and magnetic force vectors. The simulation results of the various configurations of damper show that higher magnetic force is associated with plain piston ends. The performance of filleted piston ends is superior to that of other configurations for the same magnitude of coil current and piston velocity. Design/methodology/approach – The damper design is done based on the fact that mechanical energy required for yielding of MR fluid increases with increase in applied magnetic field intensity. In the presence of magnetic field, the MR fluid follows Bingham’s plastic flow model, given by the equation τ = η γ•+τ y (H) τ > τ y . The above equation is used to design a device which works on the basis of MR fluid. The total pressure drop in the damper is evaluated by summing the viscous component and yield stress component which is approximated as ΔP = 12ηQL/g3W + CτyL/g, where the value of the parameter, C ranges from a minimum of 2 (for ΔPτ ΔPη less than approximately 1) to a maximum of 3 (for ΔPτ/ΔPη greater than approximately 100). To calculate the change in pressure on either side of the piston within the cylinder, yield stress is required which is obtained from the graph of yield stress vs magnetic field intensity provided by Lord Corporation for MR fluid −132 DG. Findings – In this work, three different finite element models of MR damper piston are analyzed. The regression equations, contour plots and surface plots are obtained for different parameters. This study can be used as a reference for selecting the parameters for meeting different requirements. It is observed from the simulation of these models that the plain ends model gave optimum magnetic force and 2D flux lines with respect to damper input current. This is due to the fact that the plain ends model has more area when compared with that of other models. It is also observed that filleted ends model gave optimum magnetic flux density and yield stress. As there is reduced pole length in the filleted ends model, the MR fluid occupies vacant area, and hence results in increased flux density and yield shear stress. The filleted ends assist the formation of dense magnetic flux lines thereby increasing the flux density and yield stress. This implies that higher load can be carried by the filleted ends damper even with a smaller size. Originality/value – This work is carried out to manufacture different capacities of the dampers. This can be applied as vibration controls.

Study on Magnetic Field for Navigation of Articulated Needle

2012 ◽  
Vol 152-154 ◽  
pp. 952-957
Author(s):  
Hua Fang Huang ◽  
Yi Zhong Wang ◽  
Zong Guo Zhou ◽  
Yong Hua Chen
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Density ◽  
Permanent Magnets ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Magnetic Flux Density ◽  
Variable Direction ◽  
The Magnetic Field ◽  
Three Dimensional Space

When the magnetic articulated needle is inserting, the magnetic field which can produce the magnetic force of variable direction is required in order to implement the magnetic navigation in three-dimensional space. The paper puts forward a method for generating three-dimensional magnetic field based on the rotaion and translation of multiple permanent magnets. In this method, multiple permanent magnets form a circumference array. Every permanent magnet can rotate around the spin axis of itself in the array plane and move along the direction vertical to the array plane. Thus, in the array center, a magnetic fied which can produce the uniform magnetic flux density is obtained. The direction of magnetic fied is controllable in three-dimensional space and the magnitude of magnetic flux density is variable in a certain range. The simulations by ANSYS verify the feasibility of the proposed method.

A Mathematical Model of a Modified Voice Coil Energy Harvester

2011 ◽  
Author(s):  
Alireza Hekmati ◽  
Siamak Arzanpour
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Density ◽  
Peak Power ◽  
Magnetic Field Intensity ◽  
Magnetic Circuit ◽  
Magnetic Flux Density ◽  
Magnetic Conductor ◽  
Magnetic Circuits ◽  
The Magnetic Field

This paper presents a mathematical modeling of a modified voice coil generator, which consists of a moving coil within a fixed magnetic circuit. The simulation has been done with Comsol Multiphysics software, which is a powerful tool to demonstrate the pattern of magnetic field and calculate the induced current in the coil. In our simulations, the magnetic circuit consists of the magnetic conductor and the air gap. In this analysis, the magnetic flux density and the magnetic field intensity are calculated. Moreover, through calculation of the total reluctance of the magnetic circuit and employing the ohm’s law for magnetic circuits, the effect of the length and cross section of the total circuit on the magnetic flux are investigated. Finally, a pattern for the magnetic flux density are demonstrated and the simulation result indicates that the magnetic field is well concentrated on the coil area, therefore this prototype can capture and convert most of the kinetic energy to electricity. A prototype has been fabricated and tested on the shaker. The experimental results indicate that this setup is able to produce the maximum voltage of 0.326 V and the peak power equal to 2.605 mW in 35 Hz frequency and 1 mm peak to peak amplitude.

scholarly journals The influence of conductive passive parts on the magnetic flux density produced by overhead power lines

2019 ◽  
Vol 32 (4) ◽  
pp. 555-569
Author(s):  
Slavko Vujevic ◽  
Tonci Modric
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Density ◽  
Biological Effects ◽  
Research Work ◽  
Power Lines ◽  
Magnetic Flux Density ◽  
Human Beings ◽  
Overhead Power Lines ◽  
The Magnetic Field

There has been apprehension about the possible adverse health effects resulting from exposure to power frequency magnetic field, especially in the overhead power lines vicinity. Research work on the biological effects of magnetic field has been substantial in recent decades. Various international regulations and safety guidelines, aimed at the protection of human beings, have been issued. Numerous measurements are performed and different numerical algorithms for computation of the magnetic field, based on the Biot- Savart law, are developed. In this paper, a previously developed 3D quasistatic numerical algorithm for computation of the magnetic field (i.e. magnetic flux density) produced by overhead power lines has been improved in such a way that cylindrical segments of passive conductors are also taken into account. These segments of passive conductors form the conductive passive contours, which can be natural or equivalent, and they substitute conductive passive parts of the overhead power lines and towers. Although, their influence on the magnetic flux density distribution and on the total effective values of magnetic flux density is small, it is quantified in a numerical example, based on a theoretical background that was developed and presented in this paper.

scholarly journals Simulation: Early Detection of Brain Vessels Stroke by Applying Electromagnetic Waves Non-Invasively

2021 ◽  
Vol 9 (9) ◽  
pp. 01-10
Author(s):  
Ahmed El-Shahat ◽  
Ashraf. M ◽  
Waleed. A ◽  
K. Sayed
Keyword(s):  
Magnetic Field ◽  
Early Detection ◽  
Laminar Flow ◽  
Magnetic Flux ◽  
Flux Density ◽  
Electromagnetic Waves ◽  
Magnetic Flux Density ◽  
Permanent Disability ◽  
Stroke Type ◽  
The Magnetic Field

Introduction: Early recognition of stroke with its two types Ischemic and Hemorrhagic, is one of the most crucial research points, commonly used methods are CT- (computerized tomography), and MRI- (Magnetic resonance imaging). These techniques cause a delay in the detection of the condition, which causes permanent disability. The main reason behind the fatal consequences of stroke is the delay of detection. Therefore, this research paper aims to early detection of the type of stroke without delay until the appropriate diagnosis of each type is made, and then the appropriate treatment without delay. Method: Using a non-invasive and fast technique to determine the stroke type by wave, we simulate and design a vessel containing a liquid as a laminar flow with the same density and velocity of blood, and it was surrounded by a Homogenized multi-turn coil consisting of (n) turns to represent the magnetic field, using specific frequency (HZ) with Electrical field in coil current (A) to see the changing in magnetic flux density (MFD), Depending on the changes in MFD, the flow of blood in laminar flow can be affected by clotting (Ischemic) or Hemorrhagic (cutting) in our vessel designed. We have built three different scenarios to apply the technique which are: First: Normal Scenario (where the blood in vessel has no problem), second: clotting (ischemic, where the vessel blocked in specific three position) and Third: Cutting (Hemorrhagic, where the vessel cut in certain nine positions). Results: This paper presents-through our own design-the studying of applying the electromagnetic waves on blood inside the vessel to detect the stroke type in our three scenarios (normal, ischemic three positions or hemorrhagic nine positions), Studying the magnetic field and laminar flow. This study covered in three areas. First: coil geometry analysis, Second: stationary, and Third: frequency domain. through the changes in Magnetic Flux Density -MFD- waves. The results were promising and distinct for distinguishing between the three scenarios which are normal, ischemic (3 positions) and hemorrhagic (9 positions) the results of MFD are: 0.09 to 3.3*10^-3, 0.08 to 3.15*10^-4, 0.15 to 6.2*10^-3 respectively.

Study of the tribological properties of rolling element bearings under the effect of magnetic field

2019 ◽  
Vol 71 (10) ◽  
pp. 1200-1205
Author(s):  
Mustafa Kadıoğlu ◽  
Ertuğrul Durak
Keyword(s):  
Magnetic Field ◽  
Friction Coefficient ◽  
Magnetic Flux ◽  
Flux Density ◽  
Magnetic Flux Density ◽  
Rolling Element Bearings ◽  
Experimental Conditions ◽  
Content Type ◽  
Rolling Element ◽  
The Magnetic Field

Purpose The purpose of this study was to examine the effect of the magnetic field to the friction coefficient in the rolling element bearings which exists in electric motors. Design/methodology/approach To achieve this, the test rig was modified to adjust the density of the magnetic flux applied to the rolling ball element bearing. Experiments were carried out in the magnetic field from 0 to 7.5 mTesla at magnetic flux density range from 15, 40 and 65 N constant loads. Also, its rotary speed selected as 100, 200, 400, 800 to 1200 rpm, respectively. Findings In the majority of the experiments, it was observed that the magnetic field affected the friction coefficient. This influence reduced the friction coefficient in some experimental conditions and increased in some of them. Originality/value In the literature, there are very few studies on the effect of magnetic flux density to the friction coefficient in these rolling element bearings. It has become clear that more studies have been conducted on the effects of the magnetic field and/or electrical current on bearing damages and failures. This aspect is a study with specificity.

Compression Resistance of Magnetorheological Fluid

2010 ◽  
Vol 143-144 ◽  
pp. 624-628 ◽  
Author(s):  
Hong Yun Wang ◽  
Xiao Wang ◽  
Cheng Bi
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Yield Stress ◽  
Flux Density ◽  
Magnetic Flux Density ◽  
Compression Stress ◽  
Mr Fluids ◽  
Shear Yield ◽  
Compression Characteristics ◽  
Compression Resistance

The ability of magnetorheological(MR) fluids to resist compression in the direction of magnetic field was tested to investigate the quasi-static squeezing process of MR fluids. A experiment setup was designed and fabricated to test the compression characteristics. Under the different magnetic flux density, the curves of the MR fluids were studied for yield stress versus compression stress, compression stress versus compression strain. The compression resistance of MRF was then measured for the different magnetic flux density for comparison with the shear yield strength of the same magnetic field. The results showed that the compression resistance of the MRF was much stronger than its shear yield stress for the same magnetic field strength conditions. The compression resistance of MRF can be utilized to design new magnetorheological devices.

External Magnetic Field Control during EDM of a Permanent Magnet

2014 ◽  
Vol 1017 ◽  
pp. 806-811
Author(s):  
Hideki Takezawa ◽  
Nobuhiro Yokote ◽  
Naotake Mohri
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Flux ◽  
Permanent Magnet ◽  
Flux Density ◽  
Electrical Discharge Machining ◽  
Magnetic Flux Density ◽  
Internal Temperature ◽  
Set Up ◽  
The Magnetic Field

The effect of changes in the magnetic field on the magnetic flux density during the electrical discharge machining (EDM) of a permanent magnet is reported. During EDM of the permanent magnet, a second magnet for the external magnetic field was set up, and the internal temperature and surface magnetic flux density on the opposite surface of the permanent magnet during machining were evaluated. It was found that even though the internal temperature of the magnet remained unchanged, the surface magnetic flux density changed when the external magnetic field was varied. In addition, the magnetic field generated by the magnet changed when a plate with high permeability was pressed onto the surface of the permanent magnet.

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