Neutral Pion Electromagnetic Form Factor as a Bound System of 3 + 1 Dimensional QCD

We investigate a neutral pion electromagnetic form factor in momentum space and obtain Gaussian-like function for it. The characteristic form of our neutral pion electromagnetic form factor is consistent with the results published by Jefferson Lab Hall A Collaboration. .

The Pairing Analysis Improvement of Magnetized Structure in Electromagnetic Bulging Process in Case of Tube with Field Shaper

In the current practical science, the accuracy in the formability of metal alloys being the goal when using electromagnetic forming (EMF) technology, which is a high-speed processing technology that uses Lorentz forces to achieve plastic deformation of sheet metal;according to the previous analysis, the results have shown that in most cases, the Lorentz force acting on the workpiece (metal) is not uniform, there are uneven axial deformations of the metal plates which prevent the rapid advancement of today’s technology. In this article, we presented some advanced analyzes which will lead us to improve the technical solution for the problems of non-uniform axial deformations of the metals in the traditional tube electromagnetic forming technology (EMF). A field shaper is used as a practical forming tool to influence the magnetic field and magnetic pressure distribution, thereby improving the forming ability and result during the electromagnetic forming (EMF) process and we see that induced eddy current control is realized by changing the structural parameters of the magnetic field shaper;which improves the strength and controllability of the magnetic force that acts on the workpiece;thereby a greater radial magnetic pressure can be achieved with field shaper than the case without it;the field shaper regulates the electromagnetic force, the distribution of the magnetic pressure decreases, and the uniform force area of the tube increases which effectively enhances the uniform range of the pipe electromagnetic bulging and the electromagnetic induction coupling between the coil and the metallic workpiece is generally required to produce the Lorentz forces. Using COMSOL Multiphysics® simulation software helped us to accurately represent the real world, simulating multiple physical effects that happened in this model during the process.

3D modeling and deformation analysis for electromagnetic sheet forming process

Electromagnetic forming （EMF） is a high-speed forming method which can be quite effective in increasing the forming limits of metal sheet. However, the EMF process is complicated due to magnetic-structure coupling analysis. Numerical simulation offers an opportunity to overcome the problem. Nevertheless, most present models for EMF process are limited to 2D axisymmetric model. So, a three-dimensional （3D） finite element model was established to analyze the electromagnetic sheet bulging. The contact between the sheet and the die and the effect of sheet deformation on the magnetic field analysis were both taken into consideration during the forming process. The simulation results of deflection at the sheet center and 20 mm away from the center were in agreement with the experimental ones. The plastic strain energy and plastic strain were analyzed.

Alternative flat coil design for electromagnetic forming using FEM

Electromagnetic forming （EMF） is a high velocity forming process that uses impulse magnetic force. Coil is an important component of EMF system which needs to be designed depending on application. Flat spiral coils are generally used for electromagnetic forming of sheet metals. However, with this type of coil the central portion of the workpiece experiences marginal magnetic force. This leads to in-sufficient deformation at this portion and other problems like air entrapment. In this study, a conceptual design of flat coil was proposed for better distribution of magnetic forces over the workpiece. Comparative analysis of distribution of magnetic force, magnetic field and current density using the proposed and the existing coil designs were carried out using FEM. The result indicates that the proposed coil design produces comparatively better magnetic force distribution over the workpiece. Calculation of self-inductance of such coils was also carried out and was compared with FE simulation.

Effects of coil length on tube compression in electromagnetic forming

The effects of the length of solenoid coil on tube compression in electromagnetic forming were investigated either by theory analysis or through sequential coupling numerical simulation. The details of the electromagnetic and the mechanical models in the simulation were described. The results show that the amplitude of coil current waveform and the current frequency decrease with the increase of the coil length. And the peak value of magnetic pressure is inversely proportional to the coil length. The distribution of the magnetic force acting on the tube is inhomogeneous while the tube is longer than the coil. The shortened coil length causes the increases of the maximum deformation and energy efficiency. The numerically calculated result and the experimental one of the final tube profile are in good agreement.

Grain Refinement Mechanism and Texture Evolution of Polycrystalline Cu Sheets during the Electromagnetic Forming Process

The grain refinement mechanism and texture evolution of electromagnetically formed polycrystalline Cu sheets were investigated using the electron back-scattered diffraction(EBSD) technique. It is found that the average grain size decreases from 35.88 μm to 8.77 μm. The grain refinement was mainly attributed to dynamic recrystallization(DRX) at the grain boundary regions of bulged Cu samples where the inhomogeneous dislocation density and the large lattice misorientation were observed. The DRX mechanisms at the grain boundaries were discussed with respect to the strain-induced grain boundary migration nucleation. Moreover, the orientation distribution function(ODF) of the sample with the strain of 50% demonstrated a strong {110}<211> texture and a relatively weak {001}<100> texture. The texture evolution was discussed using the plastic work values of the grains with various orientations, which were calculated according to the Taylor model and the virtual work principle. The experimental results show that the expended plastic work of the grains with {110} orientation is 9.69 MPa, which is distinctly higher than those of the grains with the {001} and {111} orientations. This indicates that the formation of the {110} orientated texture would be preferred with increasing strain in good agreement with the experimental result.

INSIDE BEADING OF A HEXAGONAL TUBE BY ELECTROMAGNETIC FORMING

In this paper local compressive deforming of a hexagonal tube of aluminum (JISA1050) is investigated by an electromagnetic forming. The hexagonal tubes are annealed for 1h. at 400℃， which have 55mm width with 1mm thickness, and 10mm corner edius. The deformed ation of the hexagonal tube, i.e., bead width, is 10, 15, 20mm, respectively. The magnetic flux density in the gap between the field shaper and the external surface of hexagonal tube is measured, and the result is that the magnetic flux density for a given voltage is almost identical along the gap) and decreases with increasing the gap. The profiles and the strain distribution of the hexagonal tube de- formed are affected by the change Of the charging voltage and the dimensions of a bead width. The greater compressive strum in the cireuwtrential direction is develOPed on plane part near corner,while tensile strain on the corner occurs. A metallic block is inserted inside the hexagonal tube so that uniform profile can be obtained. The simulation of the forming is performed by a finite-element method and compared with the experimental results.

Study of Magnetic Force Distribution for Electromagnetic V-shape Bending Forming of Small Size Flat Sheet

Electromagnetic V-shape bending of small size sheet blank is investigated numerically and experimentally. Three-dimensional electromagnetic field models are established to calculate the magnetic force distribution on the sheet by software ANSYS / EMAG. Series of electromagnetic V-shape bending forming experiments are presented,in which small size uniform pressure coil and big size round flat spiral coil are used. The results show that small size uniform pressure coil is not suitable for electromagnetic forming of small size flat sheet,and the coil is susceptible to failure such as bulging,ablation and cracking. When the plane dimension of round flat spiral coil is bigger than sheet blank sizes,the induced current crowding effect will be resulted which seriously influence the magnetic force distribution on the sheet. In this case,magnetic force distribution can be adjusted through the change of the relative position between coil and sheet,the desired deformation can be obtained finally. Therefore,big size round flat spiral coil can be well applied to electromagnetic V-shape bending forming of small size flat sheet.

Finite element modeling and experiment for behavior estimation of AlMn0.5Mg0.5 sheet during electromagnetic forming

The electromagnetic forming is a procedure of high-speed processing,which favors the increase of the formability of some plastically deformed metals.In order to evaluate the capacity of some light metals,such as aluminum and its alloys,to be deformed through this procedure,it is useful to know the stress and strain state that occurs in the material during forming.In this work,the modeling of stresses and strains in electromagnetically deformed AlMn0.5Mg0.5 sheet was made.The modeling was achieved using the finite element method and it was verified through experimental tests.To determine the residual stresses,the X-ray diffraction method was used.The strains were established by measuring the displacements of the nodes in the network inscribed on the specimen by means of three coordinates measuring machine.A good agreement between the modeling results and experimental data was found.

Magnetic pressure in electromagnetic tube forming with echelon coil

The effects of geometrical characteristics of echelon coil on the magnetic pressure distribution and their contribution to the final shape of parts were focused and investigated through experiments and numerical simulation using FEM software ANSYS. The results show that the geometrical characteristics of echelon coil play a key role in controlling the magnetic pressure acting on the tube. They show a hump-like distribution near the interface between bigger diameter region and transition region of echelon coil, and affect the final shape of tubular parts then. With the reduction of relative diameter, the magnetic pressure in smaller diameter region decreases and its distribution gradient in transition region increases. With the augment of relative length, the magnetic pressure increases in bigger diameter region, while it almost remains constant in smaller diameter region, and the gradient in transition region enhances sharply. The distribution of magnetic pressure in the axial direction of tube agrees well with the profile of specimen.

Magnetic force distribution and deformation law of sheet using uniform pressure electromagnetic actuator

The distribution of magnetic forces and current on sheet and coil was analyzed in detail according to the structural parameter of the coil which was invalid.The result shows that the current direction based on simulation result agrees with the principles of uniform pressure electromagnetic actuator.The reason for coil failure was proposed.Then the magnetic forces on the sheet were input into an explicit finite element software ANSYS/LS-DYNA to analyze the deformation law of the sheet.

Numerical modeling and deformation analysis for electromagnetically assisted deep drawing of AA5052 sheet

Electromagnetic forming(EMF)is a high-velocity manufacturing technique which uses electromagnetic(Lorentz)body forces to shape sheet metal parts.One of the several advantages of EMF is the considerable ductility increase observed in several metals,with aluminum featuring prominently among them.Electromagnetically assisted sheet metal stamping(EMAS)is an innovative hybrid sheet metal processing technique that combines EMF into traditional stamping.To evaluate the efficiency of this technique,an experimental scheme of EMAS was established according to the conventional stamping of cylindrical parts from aluminum and the formability encountered was discussed.Furthermore,a "multi-step,loose coupling" numerical scheme was proposed to investigate the deformation behaviors based on the ANSYS Multiphysics/LS-DYNA platform through establishing user-defined subroutines.The results show that electromagnetically assisted deep drawing can remarkably improve the formability of aluminum cylindrical parts.The proposed numerical scheme can successfully simulate the related Stamping-EMF process,and the deformation characteristics of sheet metal reflect experimental results.The predicted results are also validated with the profiles of the deformed sheets in experiments.

A Review of Electromagnetic Energy Regenerative Suspension System&Key Technologies

The active suspension has undoubtedly improved the performance of the vehicle,however,the trend of“lowcarbonization,intelligence,and informationization”in the automotive industry has put forward higher and more urgent requirements for the suspension system.The automotive industry and researchers favor active energy regeneration suspension technology with safety,comfort,and high energy regenerative efficiency.In this paper,we review the research progress of the structure form,optimization method,and control strategy of electromagnetic energy regenerative suspension.Specifically,comparing the pros and cons of the existing technology in solving the contradiction between dynamic performance and energy regeneration.In addition,the development trend of electromagnetic energy regenerative suspension in the field of structure form,optimization method,and control technology prospects.

Electromagnetic Confinement and Shaping for Plate-Form Part

than 2.2, the electromagnetic pressure acting on melt can be simply expressed as Pm =B^2/wμ, and the melt shape would be known only by measuring the distribution of magnetic flux density. As a is small and makes the ratio a/8 less than 2.2, the melt shape and electromagnetic pressure for confining and shaping are determined not only by magnetic flux density B but also by melt thickness a, electromagnetic parameter μγ and current frequency f. In this paper, an equation used to calculate electromagnetic pressure acting on 'thin plate-form melt' is brought forward. The equation gives a precise relationship between electromagnetic pressure factor p and melt thickness a, electromagnetic parameter μγ and current frequency f.

Tendency of homogeneous radial deformation during electromagnetic compression of aluminium tube

Electromagnetic forming is one of the high-rate forming methods that can be extensively used to form and join axisymmetric metal sheet and tube. Tendency of homogeneous radial deformation during electromagnetic compression of aluminium tube was investigated through the design optimization method based on sequential coupling numerical simulation and experiments. The results show that the tendency depends on the length ratio of tube to coil (R), which has a critical value (Rc) corresponding to the relatively homogeneous radial deformation along axial direction. The tube length relative to Rc is insensitive to the discharge voltage. When R is greater than Rc, the deformed tube presents horn shape and the shorter coil makes for local deformation. If R is less than Rc, the deformed tube presents drum shape and the longer coil contributes to larger deformation at tube end. Rc increases with coli length and could approach to 1; inversely, it could approach to 0. These results indicate the design optimization method based on the sequential coupling numerical simulation is feasible, which can be used to realize the controllable and precise deformation of metal tube.

Proton and Neutron Electromagnetic Form Factors Based on Bound System in 3 + 1 Dimensional QCD

We propose a new description of a nucleon as a pair of pions. The baryon number of our description of nucleon is not 1 but 0. However, this is probable because the proton spin crisis shows that the baryon spin cannot tell the number of composing quarks anymore. Because we use the derived pion wave function to describe a nucleon, our description has automatically the pionic degree of freedom and can be compared to the constituent quark model. Using this description, we investigate the electric charge and magnetization density functions of protons and neutrons. The electric charge density function of neutron is quite similar to those of Galster model and Maints data except the magnitude of singularity. The density functions of proton also show the similar behavior as those of Kelly’s except near origin. Taking the Fourier transform of the density functions, we obtain the Sachs electromagnetic form factors that can be compared to those in the parametrization derived by Ye et al.

Numerical simulation on electromagnetic field,flow field and temperature field in semisolid slurry preparation by A-EMS

A two-dimensional computational model coupling an annular electromagnetic stirring（A-EMS） with a macroscopic heat and fluid flow analysis in Al-alloys semisolid slurry preparation was developed.The dynamic evolutions of the electromagnetic field,flow field,and temperature field were presented successfully by commercial software ANSYS 10.0 with corresponding experimental verification.A horizontally rotational electromagnetic field and,thereby,a more intensive velocity field were uniformly distributed in the stirred melt even at commercial frequency,and thus,a lower temperature difference in the stirred melt and subsequent uniformly fine microstructures were obtained compared with the normal electromagnetic stirring.The simulation results were in good agreement with experimental ones.

Hot top electromagnetic casting research of Al thin slab

The hot top EMC (electromagnetic casting) method was put forward, namely, the shape of top liquid column was formed by the hot top in the screen and the semi suspended liquid column was formed by the electromagnetic force nearby the liquid solid interface frontier. Using the numerical simulating technique, the temperature distribution was discussed, the effect of parameters such as upper conduct distance (UCD), cooling water rate of flow, pouring temperature and liquid column height on casting velocity were studied, the relationship among them was confirmed finally. According to the calculated results, the hot top EMC shaping system was designed and a lot of experiments were performed. The pure Al thin slabs of 480 mm×20 mm×850 mm were made successfully. The result showed that the casting velocity curve obtained experimentally almost coincides to the calculated one.

THE ELECTROMAGNETIC FIELD CALCULATION AND ANALYSIS OF LEVITATION MELTING WITH COLD CRUCIBLE

In this paper, using the quasi-3D coupled current method, the influences of structure of cold crucible, the power frequency, the electricity property of melt, the coil position and current on the electromagnetic field (EMF) and the levitation characteristics in the melting processes are analyzed. It is shown that in the processes of levitation melting with cold crucible, the power frequency and cold crucible structure are the decisive factors for the ability of magnetic flux penetrating into cold crucible. The magnetic flux density in cold crucible is reduced as the increasing of power frequency, and this tendency becomes stronger when the power frequency is higher than 100kHz. The segmented structure of cold crucible can reduce the induction eddy in itself effectively, and the higher the power frequency is, the better the result is. So, a cold crucible can be segmented into 16-20 sectors for high frequency electromagnetic field and/or 8-12 sectors for lower frequency one. It is also shown that the levitation force of melting charge is related to coil current as a parabolic function.

A FINITE-ELEMENT ANALYSIS OF ELECTROMAGNETIC SHEET METAL-EXPANSION PROCESS

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