• Title, Summary, Keyword: electromagnetic force

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A study on the Continuous Elimination of Inclusions in Al Alloy by Electromagnetic Force (전자기력을 이용한 알루미늄 합금중 개재물의 연속적 제거에 관한 연구)

  • Yoon, Eui-Pak
    • Journal of Korea Foundry Society
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    • v.22 no.3
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    • pp.130-136
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    • 2002
  • The growing use of aluminum for castings over the past decade has brought with it the increased scrutiny of component properties. One area that has received much attention is the effect of in inclusions - or impurities particles held in the metal - on casting properties. A new method of electromagnetic separation for removal of inclusions in aluminum alloy melts is proposed. The principle is that as the electromagnetic force induced in metal acts on inclusions due to low electric conductivity, they are moved to the direction opposite to electromagnetic force and can be separated and removed from the melt. Experiments were carried out on A356 melt mixed alumina particles and commercial Al alloys of ADC 10 and 12. In the experiment using A356, it was proved that $Al_2O_3$ particles was separated and removed continuously from matrix melt by electromagnetic force. Based on these results, the continuous separation experiment that used ADC 10, 12 was carried and the cleanliness of melt was assessed by the amount of porosity, hydrogen contents, PoDFA and mechanical properties through tensile test. As the results of analyses, the amount of porosity and hydrogen contents decreased without variation of chemical composition in the specimen that passed the electromagnetic continuous separator. In addition, tensile strength and elongation of this specimen increased by $20{\sim}30%$ because of reduction of inclusions.

Dynamic interaction analysis of actively controlled maglev vehicles and guideway girders considering nonlinear electromagnetic forces

  • Min, Dong-Ju;Lee, Jun-Seok;Kim, Moon-Young
    • Coupled systems mechanics
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    • v.1 no.1
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    • pp.39-57
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    • 2012
  • This study intends to explore dynamic interaction behaviors between actively controlled maglev vehicle and guideway girders by considering the nonlinear forms of electromagnetic force and current exactly. For this, governing equations for the maglev vehicle with ten degrees of freedom are derived by considering the nonlinear equation of electromagnetic force, surface irregularity, and the deflection of the guideway girder. Next, equations of motion of the guideway girder, based on the mode superposition method, are obtained by applying the UTM-01 control algorithm for electromagnetic suspension to make the maglev vehicle system stable. Finally, the numerical studies under various conditions are carried out to investigate the dynamic characteristics of the maglev system based on consideration of the linear and nonlinear electromagnetic forces. From numerical simulation, it is observed that the dynamic responses between nonlinear and linear analysis make little difference in the stable region. But unstable responses in nonlinear analysis under poor conditions can sometimes be obtained because the nominal air-gap is too small to control the maglev vehicle stably. However, it is demonstrated that this unstable phenomenon can be removed by making the nominal air-gap related to electromagnetic force larger. Consequently it is judged that the nonlinear analysis method considering the nonlinear equations of electromagnetic force and current can provide more realistic solutions than the linear analysis.

Comparison of Biot-Savart's Law and 3D FEM in the Study of Electromagnetic Forces Acting on End Winding

  • Kim, Ki-Chan
    • Journal of Electrical Engineering and Technology
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    • v.6 no.3
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    • pp.369-374
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    • 2011
  • An induction motor operated with high voltage source generally generates high current in starting mode and has a long transient time after being started. This large and sustaining starting current causes the end windings of the stator to have excessive electromagnetic force. This force is the source of vibration and has a negative and serious influence on the insulation of end windings. Therefore, designing the end winding part with an appropriate support system is needed. To design the support ring enclosing the end windings, we analyze the distribution of electromagnetic force on the end windings by applying the Biot-Savart's law and the 3D finite element method (FEM), and comparing two simulation methods. Finally, we verify the safety of the support structure of the end winding part using stress analysis, which is analyzed with the electromagnetic forces from the 3D FEM simulation.

Movement Characteristics Analysis of Single Phase Transformer Winding Using Finite Element Method (유한요소법을 이용한 단상변압기권선의 운동특성해석)

  • Choi, Myoung-Jun;Kim, Hyung-Seok;Park, Il-Han
    • Proceedings of the KIEE Conference
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    • pp.104-106
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    • 1996
  • In this paper, the dynamic motion driven by electromagnetic force of transformer windings is modeled and its characteristics are numerically analyzed. The electromagnetic field is obtained using the 2D finite element method taking account of anisotropic property of iron core, and the electromagnetic force on the transformer winding is calculated from Lorenz's force formula using the field distribution result. The system motion equation driven by electromagnetic force and gravitational force is numerically analyzed using the 4-order Runge-Kutta algorithm. Above analyses procedure is applied to a single-phase core-type transformer to validate its algorithm.

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A Study on the Effect of External Electromagnetic force in MIG Welding (MIG 용접 시 외부 전자기력이 미치는 영향에 관한 연구)

  • Kim Jae Seong;Kim Yong;Ryu Deok Hui;Lee Bo Yeong
    • Proceedings of the KWS Conference
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    • v.43
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    • pp.171-173
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    • 2004
  • Electromagnetic force is one of the most important factor that effect on metal transfer mode, short-circuit rate, spatter generation rate and mechanical properties of weld metal etc. Also, shielding gas and welding current have influence on metal transfer mode in GMAW. In this paper, different ways for external electromagnetic forces are applied by attaching cylindrically rounded conducting wire solenoid on touch tip holding. With the applied electromagnetic field, the arc transfer mode changes from normal mode to rotating mode and spatter generation decreased in electromagnetic fields(N-pole). In MIG welding, the influences of electromagnetic force on the spatter generation showed different tendency as in the $CO_2$ welding. It is possible reasons were discussed.

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Response of Spatially Developing Turbulent Boundary Layer to Spanwise Oscillating Electromagnetic Force (횡 방향 진동하는 전자기력에 대한 공간 발달하는 난류 경계층의 반응)

  • Lee, Joung-Ho;Sung, Hyung Jin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.11
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    • pp.1189-1198
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    • 2005
  • Direct numerical simulations were performed to investigate the physics of a spatially developing turbulent boundary layer flow subjected to spanwise oscillating electromagnetic forces in the near wall region. A fully implicit fractional step method was employed to simulate the flow. The mean flow properties and the Reynolds stresses were obtained to analyze the near-wall turbulent structure. It is found that skin friction and turbulent kinetic energy can be reduced by the electromagnetic forces. The decrease in production is responsible fur the reduction of turbulent kinetic energy. Instantaneous flow visualization techniques were used to observe the response of streamwise vortices and streak structures to spanwise oscillating forces. The near-wall vortical structures are affected by spanwise oscillating electromagnetic forces. Following the stopping of the electromagnetic force, the flow eventually relaxes back to a two-dimensional equilibrium boundary layer.

Study on the two-dimensional Formation Control of Free Surface of Magnetic Fluid by Electromagnetic Force (전자기력에 의한 자성유체의 2차원 자유표면 형상 제어에 관한 연구)

  • 안창호;지병걸;이은준;박명관
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.979-982
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    • 2003
  • In this study, because of change in electromagnetic force, deformation of the free surface motion of a magnetic fluid is changed. Deformation of the free surface motion of a magnetic fluid for the change in electromagnetic force is discussed and carried out theoretically and experimentally on the basis of Rosensweig Ferrohydrodynamic Bernoulli Equation. Objective of this study explicates free surface motion by electromagnetic force and planes to designed controller. To control free surface of magnetic fluid, it embody designed two-dimensional free surface form of magnetic fluid. By using this characteristics, they applied to oscillator for surface control, flow control, boundary layer control. Strength of magnetic field and height of free surface of magnetic fluid measure as a hall-effect sensor. As performing height control of magnetic fluid, the result will be presented possibility of free surface deformation control.

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A Study on the Characteristic of Noise and Vibration in 3-phase Induction Motor for the Forklift (전동 지게차용 3상 유도 모터의 소음 진동 특성에 대한 연구)

  • Kim, Woo-Hyung;Chung, Jin-Tai
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.1
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    • pp.3-9
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    • 2009
  • This paper presents the reduction of acoustic noise generated by electromagnetic force in an induction motor of the electrical forklift. After summarizing the electromagnetic excitation forces due to the interaction between the stator/rotor slot permeance and the stator winding magnetomotive force, the effects of the electromagnetic force on the noise and vibration of an induction motor are analyzed. In order to experimentally identify the noise sources of the motor, the signal analyses for noise and vibration are performed by using waterfall plots of noise and vibration spectrums. It is found that severe noise and vibration are caused by the electromagnetic force when the mode number of the excitation shape for a stator is low. Furthermore, it is verified that the motor noise is amplified if the excitation frequency of the electromagnetic force coincides with one of the natural frequencies of the stator. It is experimentally demonstrated that this severe noise can be considerably reduced by structure modifications. Finally, some design guidelines are suggested to develop an induction motor with a low level of noise.

Effect of Process Parameters in Electromagnetic Forming Apparatus on Forming Load by FEM (유한요소해석을 통한 전자기 성형장비 공정변수의 성형력에 미치는 영향)

  • Noh, Hak Gon;Park, Hyeong Gyu;Song, Woo Jin;Kang, Beom Soo;Kim, Jeong
    • Journal of the Korean Society for Precision Engineering
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    • v.30 no.7
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    • pp.733-740
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    • 2013
  • The high-velocity electromagnetic forming (EMF) process is based on the Lorentz force and the energy of the magnetic field. The advantages of EMF include improved formability, wrinkle reduction, and non-contact forming. In this study, numerical simulations were conducted to determine the practical parameters for the EMF process. A 2-D axis-symmetric electromagnetic model was used, based on a spiral-type forming coil. In the numerical simulation, an RLC circuit was coupled to the spiral coil to measure various design parameters, such as the system input current and the electromagnetic force. The simulation results show that even though the input peak current levels were at the same level in each case, the forming condition varied due to differences in the frequency of the input current. Thus, the electromagnetic forming force was affected by the input current frequency, which in turn, determined the magnitude of the current density and the magnetic flux density.

A Study on the Attracting Force of an Electromagnetic Contactor with Shading Coil (Shading Coil이 장치된 전자개폐기의 흡인력에 관한 연구)

  • 김시화;노창주
    • Journal of the Korean Institute of Navigation
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    • v.6 no.2
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    • pp.35-55
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    • 1982
  • The attempt of this paper is to examine the basic theory on the analysis of the effect of a shading coil fitted to an electromagnetic contactor, and to compare experimentally the attracting force of an AC electromagnetic contactor with that of a DC electromagnetic contactor, with varying the airgap length. Equations are also proposed for calculating the AC and DC attracting force per unit consumption wattage by using the circuit constants measured from the experiment, and these calculated attracting forces are compared with those actulally measured, and then, the experimental contactor is examined in the view of its design. The calculated attracting forces are appeared to coincide well with the measured ones and the experimental contactor fitted with shading coil is revealed not so well designed for reducing the fluctuation of the attracting force.

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