Papers by Keyword: Magnetic Field

Abstract: In the paper, a new polishing head is researched and developed. How to set a magnetic feild is a key factor in magnetic-electrochemical compound polishing. To add a magnetic field that is parallel to electrical field, the electrochemical reaction can be changed greatly. Additionally, to add a magnetic field whose direction is changed to and fro, the efficiency of the polishing can be improved especially. In order to adapt to this theory, a new polishing head in magnec-electrochemical compound polishing is required resarch and development. Furthermore,the tool can be fixed on spindle of CNC easily and the tool is flexible so it can make the polishing head and workpiece touch evenly each other. Especially being noticed, the head of magnetic-electrochemical compound polishing tool is a series in order that the head can be replaced conveniently according to different surface. At last, the tool is tested and its function is perfect.

Abstract: A dual-stator toroidal motor with hybrid excitation was proposed and its structure and operating principal were introduced. The spiral currents of worm armature coils were resolved into two orthogonal components. The FEM analytic models for current components were built. Distributions of static magnetic field were simulated. Air gap flux density curves were obtained. The simulation results justify the rationality of the electromagnetic parameters of the motor. The research results are useful for analyzing electromagnetic characteristics of the motor, and offer meaningful instruction for further research and practical application of the novel motor.

Abstract: Abst r a c t -Magneto rheological aqueous is an old advancing to the bazaar at top speed. Excellent appearance like fast response, simple interface amid electrical ability ascribe and automated ability output, and absolute controllability accomplish MRF technology adorable for abounding applications.The aim of this project is preparation of MR-fluids by using the different types of carrier fluid mixed with iron powder and stability and magnetic properties are analysed. Thesedimentation of iron particles can be reduced by using additives. The sedimentation can be analysed by boundary variation of the clear fluid to the fluid turbulence. The viscosity of smart fluid can be increased by varying the applied magnetic field.The performance of the MR-damper depends on the applied maximum magnetic field and the hydraulic circuit design. The MR-damper force by increasing the magnetic field can be analysed by sing the FEMM V4 Software.Damping force depends on the excitation of current and magnetic field.Key words: Rheological, magnetic field, damping force, FEMM, flux density

Abstract: The changing magnetic field will induce eddy currents in the conductor. These currents will dissipate energy in the conductor and generate drag force. It is found that Aluminium is the best material as conductor compared to Copper and Zinc. Also, it is found that the larger thickness of disc, more number of turns of electromagnet and higher electrical conductivity of conductor influences the generation of greater braking torque. Conventional braking system relies on adhesion force between rail and wheel. It is found that a brake built up from permanent magnet pieces that combine both magnetic rail brake and eddy current brake permits the most profitable braking action through the whole range of acceptable speeds. Permanent magnet eddy current brake uses Neodymium - Iron - Boron (NdFeB) magnets. The analysis of permanent magnet eddy current shows that the parallel magnetised eddy current topology has the superior braking torque capability. In electrically controlled eddy current braking system subjected to time varying fields in different wave forms, the triangular wave field application resulted in highest braking torque. Electromagnetic brakes were found to interfere with the signalling and train control system. Permanent magnet eddy current brakes are a simple and reliable alternative to mechanical or electromagnetic brakes in transportation applications. Greater the speed greater is the eddy current braking efficiency. Hence, author intends to work on the development and investigation of permanent magnet eddy current braking system.

Abstract: The constitutive equations of MEE materials are used to derive the finite element equations involving the coupling between mechanical, electrical and magnetic fields. The candidate materials for this study are piezoelectric (BaTiO₃) and magnetostrictive (CoFe₂O₄) material. The linear buckling and vibration behavior of layered MEE beam under uniform magnetic field is carried out using finite element method. The present study is limited to clamped-clamped boundary conditions. The influence of stacking sequences and piezoelectric coupling on critical buckling magnetic field and vibration behaviour is investigated.

Abstract: To provide appropriately high and uniform magnetic field for micro electroforming process, a permanent magnet generator was specially developed which based on the fundamental process requirements. On the basis of determining the number of permanent magnet combinations numerically. Mainly, the geometrical shape of the permanent magnet blocks and magnetic circuit structure were optimized, and then the working gap regulating mechanism for this generator was designed. Utilizations indicated that the developed generator met the requirements well.

Abstract: Phosphate buffer solution (PBS) was exposed for different times to static magnetic field (MF) generated from six neodymium magnet (B=250mT) at flow conditions. The PBS conductivity and DO were measured as a function of time following the application of MF. It was found that the MF increases the PBS conductivity, and decreases the DO; they all have largest effect at the flow rate of 3m/s. Besides electrochemical reasons, this maybe can explains why the MFC have good performance by exposure to MF.

Abstract: We report nanotesla resolution in a three-phase Metglas/FeNi/PZT-5A multiferroic composite with one end rigidly clamped operating in the first-order bending resonant mode for low-frequency magnetic field detection. Strong bending magnetoelectric (ME) couplings induced by the ununiform strain distribution in the free-clamped magnetostrictive beam are achieved without the benefit of nonmagnetic tip mass, and its natural resonant frequency is much lower than that in operating free-free mode. In addition, high-permeability materials Metgals are attached on the magnetostrictive beam for magnetic flux concentrating and resolution improvement. Experimental results reveal that the three-phase ferromagnetic/magnetostrictive/piezoelectric composite with a cantilever beam structure exhibits a high bending ME coefficient of ~32.17 V/cm·Oe at the resonant bending frequency of 819Hz under Hdc=175Oe. At the resonant excitation, the maximum resolution of 7nT is acquired under Hac=1Oe. The proposed ME cantilever structure with high resolution provideds a promising application in low-frequency magnetic transducer and sensors.

Abstract: With the development of electric power system, Power-frequency Magnetic Field (MF) has become a matter of concern recently. In order to speed up the computation and modeling process, the small-scale experimental technique and simplified model for air-core reactors are introduced as a novel way to assess the MF of air-core reactors in this paper. Firstly, the scaling rules of the parameters for air-core reactors are summarized. Then, the scaling rules modification is put forward to reduce the error. Thirdly, three simplified models were established for air-core reactors, including one loop model, two loops model and three loops model. It is concluded after that the two loops model in configuration 2 can be considered as the optimal simplified model.

Abstract: Ceramic coatings were prepared on ZM5 magnetism substrate by micro-arc oxidation method with and without magnetism filed in silicate electrolyte. The morphology of the MAO coatings was investigated by scanning electron microscope (SEM). The friction coefficient of the MAO coatings prepared with magnetism is about 0.2 and more stable than the coatings prepared without magnetism. The polarization test indicated that the coating prepared with magnetism has better corrosion resistance.