Papers by Keyword: Magnetic Force

Abstract: Single Point Incremental Forming (SPIF) has recently introduced the concept of material formability enhancement through localized deformation. Since material is processed by means of a pin tool attached to spindle, physical interference (especially in vertical direction) limits attainable shapes with the conventional process. The aim of the following work is to increase the variety of achievable geometries with SPIF through in-process magnetic field assistance. An innovative configuration managing SPIF tool movement using magnetic force is proposed. With this in mind, a magnet configuration was designed to generate a vertical load able to plastically deform a 0.5 mm thick AA1100 aluminum sheet. Experiments were carried out to prove the concept by manufacturing a truncated cone; the results demonstrated the feasibility of Magnetic Field-Assisted SPIF.

Abstract: Process of vertical vibrations of the weight suspended on a spring at harmonic kinematic excitation is examined. It is shown that the resonance tuning of a system can be done with the use of magnetic force which occurs if the coil turns while moving cross external magnetic field lines.

Abstract: This paper presents a design of mini actuator without using permanent magnet for auto-focus (AF) compact camera module (CCM) built on mobile phone, tablet PC and notebook. The current through the coils of electromagnets will yield magnetic force to move the moving part up and down. Comparing with conventional spring-type voice coil motor (VCM) and non-spring type VCM, the proposed actuator eliminates the concerns of rare earth supply and magnetic flux leakage which can fail the function of magnetic flux sensitive device such as e-compass. The proposed actuator also simplifies the power converter design from bipolar scheme as required by conventional non-spring type VCM to unipolar. A comprehensive electromagnetic analysis is performed by using finite element method to characterize the performance of the proposed actuator. Numerical simulations demonstrate that the magnetic flux leakage in the proposed actuator is much smaller than those by conventional design.

Abstract: The unprecedented attempt has been made to fully expand classical and often quoted (above all by magnetic separation regimes and conditions analysis) expression for the force affecting the ferroparticle in magnetic field with the functional character of the following parameters of this expression being taken into account: magnetic induction, magnetic gradient and ferroparticle magnetic susceptibility. For this purpose a particular case of force impact has been analyzed in field approximating one-dimensional field. This field is produced in module of two distantly oriented magnetic elements. The obtained dependences for magnetic induction, magnetic gradient and ferroparticle magnetic susceptibility (according to distance x to polar surface one of the magnetic elements) have been used. By the analysis the fact has been taken into account that ferroparticle magnetic susceptibility depends on its shape as well as substance magnetic susceptibility depends, in its turn, on magnetic field intensity around ferroparticle. In other words, magnetic susceptibility of material depends on distance x to polar surface usually being ignored. The analysis of the following expanded variant of magnetic force expression allows to determine that phenomenological dependence (on parameter x) which has a very simple exponential form can be an alternative to this expression. Such dependence can be reasonably used by decision-making in theoretical and practical tasks of magnetic separation. The undertaken attempt to specify the role of another parameter B₀ – magnetic induction on polar surface (that is often considered as the most essential) – shows the power (approximating square) character of magnetic force concerning this parameter.

Abstract: The effect of high magnetic field on diamagnetic fluid flow has been studied by in-situ optical observation. The Schlieren optics utilizable under high magnetic fields was developed to carry out in-situ observation of the behavior of feeble magnetic fluids. Using a crystal of the diamagnetic aluminum potassium sulfate dodecahydrate, the behavior of the downward flow of high concentration solution in the sample dissolution process was observed. It was found that the direction of diamagnetic fluid flow was changed under spatially varied magnetic field. This phenomenon was understood qualitatively by considering the magnetic force acting on the high concentration solution and the surrounding solution.

Abstract: The paper presents numerical modeling of an Axial Active Magnetic Bearing (AAMB) based on two-dimensional (2D) magnetic field computation. The calculations, assisted by the Finite Element Method (FEM), have focused on the determination of the magnetic flux density and the magnetic force. Obtained magnetic field parameters were then measured and verified on a physical model.

Abstract: Magnetic fluid is the key core of magnetic fluid sensor. Here magnetic model of magnetic fluid is analyzed. The magnetic curve of magnetic fluid is divided into 3 parts and the liner area is presented to make magnetic fluid sensor more sensitively. The magnetic force of magnetic fluid in magnetic field is calculated and analyzed. The magnetic permeability of magnetic fluid in sensor could be treated as a constant in the linear area of magnetization curve. And the magnetic force of magnetic fluid in magnetic field could be ignored if the length to diameter ratio of the solenoid is large enough.

Abstract: Abstract. To improve energy harvesting performance, a resonance frequency tunable piezoelectric (PZT) energy harvester for vibrating applications was presented and investigated experimentally. A piezoelectric vibrational energy harvester (PVEH) consisted of a piezo-cantilever with a permanent magnet at its free-end and another excitation magnet fixed on vibration structure. The two magnets are placed with the same magnetic poles facing each other to produce repulsive force. The cantilever has dimensions of 70x10x0.6mm³, clamped 10mm, and two magnets sized ø10x4mm³. The testing results show that the magnetic force, denoted by the initial separated distance between the magnetic dipoles (SDMD), exerts great influence on the generated performance. With the SDMD increasing from 15mm to 40mm, the generated voltage rises from 24.4V to 40V, and the resonant frequency increases from 33.75Hz to 38.75Hz.

Abstract: To improve energy harvesting performance, a magnet-coupled piezoelectric vibration energy harvester (MCPEH) for low-level and low-frequency vibration was presented and investigated experimentally. The MCPEH consisted mainly of a piezo-cantilever with a permanent magnet at its free-end and another excitation magnet fixed on vibration structure. The magnets are used to produce magnetic attractive force to enhance energy generation. A MCPEH was fabricated with a piezo-cantilever measured 60x10x0.5mm3 and two magnets sized ø12x3mm³. The testing results show that the magnetic force, denoted by the initial separated distance between the magnetic dipoles (SDMD), exerts great influence on all of the generated voltage, optimal frequency, and effective bandwidth. With the SDMD reducing from 40mm to 15mm, the optimal frequency decrease from 32.75Hz to 30.5Hz, the effective bandwidth for the MCPEH to generated voltage of 15V rises from 2.5Hz to 7.5Hz, and the generated voltage rises from 30.4V to 44.4V.

Abstract: A design system using a magnetic force with high efficiency to assist discharging dregs out of the electrode gap during the electrochemical finishing on the surface finish process that follows turning machining process is investigated in the current study. Through the equipment attachment, magnetic-assistance during electrochemical finishing can follow the turning process on the same machine. This process can be used for various turning operations. Among the factors affecting electrochemical finishing, the magnetic-assistance is primarily discussed. The experimental parameters are magnetic strength, distance between the two magnets, current rating, on/off period of pulsed current, feed rate of workpiece, and rotational speed of workpiece. A higher current rating with magnetic-assistance reduces the finishing time and avoids the difficulty of dreg discharge. Providing a large magnetic field intensity or using a small distance between the two magnets produces a larger magnetic force and discharge ability and better finishing. A large rotational speed of the workpiece and electrode produces better finishing. Pulsed direct current can slightly promote the effect of electrochemical finishing, but the current rating needs to be increased. The magnetic-assistance during the electrochemical finishing process makes a great contribution in a short time by making the surface of the workpiece smooth and bright.