Field Shaper Research Articles

Novel multi-layer field shaper in electromagnetic manufacturing process technology of tube joining for uniform deformation

Electromagnetic joining technology is widely utilized in assembling tubular components due to its ability to exert uniform magnetic pressure. To augment this pressure, a field shaper structure has been introduced. However, the conventional design may impair the uniformity of deformation, particularly at the seam. This study presents a novel multi-layer field shaper (MLFS) to enhance deformation uniformity. The performance of the MLFS was evaluated and optimized through experimental trials and simulation analysis. The results showed that MLFS achieved a 300 % increase in minimum deformation with a 56 % reduction in the aspect ratio, demonstrating that our design effectively balances efficiency with deformation uniformity. The magnetic cubic decay formula could fit the simulation data well with R2 higher than 0.999. MLFS was found to enhance uniformity by creating a more even magnetic field that decreased the curvature near the plastic hinge. Compared to altering the interlayer thickness, adjusting the interlayer angle can further enhance uniformity. When the rotation angle is 60°, the radius range can be further reduced by 32.5 %, 39.0 %, and 12.2 % at energy levels of 27 kJ, 30 kJ, and 33 kJ, respectively. The above results indicate that by designing and optimizing MLFS, sufficiently large and uniform electromagnetic forces were obtained.

Experimental Investigation and Optimization of Electromagnetic Force Distribution of Magnet Based on Two Field Shaper Modules

Experimental Investigation and Optimization of Electromagnetic Force Distribution of Magnet Based on Two Field Shaper Modules

Experimental investigation on microstructure, hardness and corrosion resistance of an electromagnetic welded titanium-stainless steel dissimilar materials

The electromagnetic welding (EMW), often known as magnetic pulse welding, is a solid-state welding technology that is used to join two different materials using high-velocity impact. In this study an attempt was made to join the Titanium(Ti)- Stainless Steel(SS 304) materials with the help of multi turn disc coil along with the field shaper. A comparative investigation was conducted on the joint’s microstructure, as well as its mechanical and corrosion properties. Inverted optical microscopy (OM) and x-ray diffraction (XRD) were used to do the microstructural characterization of the joint. The micro-Vickers hardness test was used to analyse the material’s mechanical properties. In addition, electrochemical experiments were run on the Ti-SS 304 EMW junction as well as the component materials to establish how resistant they were to corrosion. Using an electrochemical impedance analyzer, the levels of corrosion that were caused by the structures were measured while they were submerged in a solution of nitric acid at room temperature. The microstructural pictures revealed a wave-like pattern at the material’s interface, which is evidence of strong adhesion between the components. The micro vickers hardness of the joints was within the permitted range, as was the corrosion rate.

Development of Multi-Part Field-Shapers for Magnetic Pulse Welding Using Nanostructured Cu-Nb Composite

Magnetic pulse welding (MPW) employs a strong pulsed magnetic field to accelerate parts against each other, thus forming an impact joint. Single-turn tool coils and field-shapers (FSs) used in MPW operate under the most demanding conditions, such as magnetic fields of 40–50 T with periods lasting tens of microseconds. With the use of conventional copper and bronze coils, intense thermo-mechanical stresses lead to the rapid degradation of the working bore. This work aimed to improve the efficiency of field-shapers and focused on the development of two- and four-slit FSs with a nanocomposite Cu 18Nb brazed wire acting as an inner current-carrying layer. The measured ratios of the magnetic field to the discharge current were 56.3 and 50.6 T/MA for the two- and four-slit FSs, respectively. FEM calculations of the magnetic field generated showed variations of 6–9% and 3% for the two- and four-slit FSs, respectively. The ovality percentages following copper tube compression were 27% and 7% for the two- and four-slit FSs, respectively. The measured deviations in the weld-joining length were 11% and 1.4% in the two- and four-slit FSs, respectively. Compared to the previous experiments on an entirely steel inductor, the novel FS showed significantly better results in terms of its efficiency and the homogeneity of its magnetic field.

Design of field shaper suitable for plate and experimental research on welding of dissimilar materials

Magnetic pulse welding realizes solid-state connection through a high-speed collision of materials, which can effectively overcome the welding difficulties of light metal materials. In the magnetic pulse welding system, in order to improve the welding efficiency, a field shaper is usually applied between the multi-turn coil and the workpiece to concentrate the magnetic field in the welding area, thereby improving the electromagnetic force. However, a large number of researchers are currently on the tube-welded field shaper, and very few researchers have studied the structure of the plate-welded field shaper. Therefore, this paper proposed a new field shaper for plate welding. The effect of the structure parameter of the field shaper on the magnetic field and electromagnetic force on the aluminum plate was analyzed in the COMSOL multiphysics software. The optimal structure parameters of the field shaper were selected. The plastic deformation and the generation of jets under different voltages and the welding of the same/dissimilar metal materials at different standoff distances were studied experimentally, which verifies the feasibility of the new field shaper.

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

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

A High Vacuum, High Electric Field Pulsed Power Interface Based on a Ceramic Insulator

Improving the flashover voltage in a vacuum interface between a pulsed-power system and a vacuum region has been a goal for many years. The interface problem is difficult because of the electrical, mechanical, and vacuum issues that must be satisfied simultaneously. In this paper, according to the theories of vacuum flashover and the design rules for high electric field insulators, a ceramic insulated vacuum interface is presented. The electrostatic field along the ceramic surface was obtained by ANSYS simulations. By optimizing the field shaper and shielding rings, the electric fields were well distributed and the fields around the cathode and anode triple junctions were effectively controlled. The high voltage test was carried out on a ~40 GW, ~100-ns pulser, and results show that the vacuum interface can work stably with the hold-off voltage of 600 kV. The experimental results agree with the theoretical and simulated results. Finally, the influence of the surface treatment on the ceramic flashover characteristics was also discussed.

Mechanism of oxide film removal and analysis of diffusion behavior of interfacial elements during magnetic pulse-assisted semi-solid brazing

The magnetic pulse-assisted semi-solid brazing (MPASSB) for Cu/Al tubes is proposed, in order to effectively remove oxide film to ensure the metallurgical bonding of Cu/Al brazing and joint performance. By designing a field shaper with a specific taper angle, the axial distribution of the electromagnetic force, tube deformation, and filler metal shear rheology are controlled to obtain the interface joining characteristics under different mechanical conditions. The relationship between the deformation behavior of the tube and filler metal with the interface element diffusion and metallurgical bonding is analyzed through the forming process simulation and interface microscopic characterization. In addition, the mechanical mechanism of oxide film removal is discussed as well. The results show that metallurgical bonding and element diffusion depend on the comprehensive effect of the interface compressive stress and the shear rheology of the filler metal. The larger the compressive stress, the better the oxide film removal. The stress at the bottom Cu/filler metal interface is the weakest, with an oxide layer thickness of 11.5 µm. The higher the shear rheological rate, the less the element diffusion depth. The filler metal flow rate at the bottom Cu/filler metal interface is the slowest, with a maximum depth of element diffusion of 13.5 µm. On the premise of ensuring the effective removal of the oxide film, the shear rheological rate (compressive stress) should not be too high.

Designing of a Field Shaper for Electromagnetic Crimping of Multi-Tube-Tube and Multi-Tube-Rod in Single Discharge Energy

Abstract This paper designed a unique field shaper, which can crimp multiple end tubes in single discharge energy. This design will surely provide an advantage of crimping different diameter tube-tube-tube and tube-tube-rod in single discharge energy. The design of the field shaper not only shows the feasibility of the multi-tube-tube and multi-tube-rod crimping for different electrical and fluid transfer applications but also explores the idea that multi-joining is also possible if carried out at the correct machine and tool parameters. The feasibility of the new process was proven by doing numerical analysis using the electromagnetic (EM) module of the ls-dyna software. Discussions on variables like current density, magnetic field, effective stress, impact velocity, and slit change are carried out. The work was validated using the tube deformation, the cross-sectional analysis of the crimped samples, and the impact velocity of the flyer tube that was measured using the PDV system. Post-processing of the samples was also carried out like a pull-out test, which justifies the numerical data interpreted. Some new important observation of the pressure waves generated during the process is discussed. Those intense pressure waves still exist after the peak current value is achieved during the current first cycle. As predicted, it may also be one of the reasons affecting the lifecycle of the field shaper. The design of the field shaper will provide a unique method for carrying out the multiple samples crimping in the single discharge energy and enhancing the production rate.

Toward Flexible Actuator Design for Electromagnetic Flanging of Sheet and Tube Metal

This paper proposed a new flexible actuator for electromagnetic forming processes, which combined a solenoid coil with a field shaper to tailor the distribution of the pulsed magnetic field. The leading contribution of our proposal is the flexible control of Lorentz force for forming sheet and tube metal workpieces by using the same actuator, which is difficult for the conventional electromagnetic actuator. To validate the feasibility of the proposal, the principle, design procedure, and realization of the actuator were firstly analyzed and discussed. On this basis, the forming experiments were then carried out, in which multi-step discharge processes were adopted to ensure forming quality control. Accordingly, the experimental results showed that the maximum die-fitting gaps of the flanged sheet and tube were within 0.3 mm, verifying the feasibility of the proposed actuator.

An accelerated analytical method for predicting workpiece velocity and displacement during electromagnetic forming

This paper presents complementary analytical analyses, experiments, and numerical simulations of the electromagnetic tube compression (EMTC) process using a multi-turn axisymmetric coil with a field shaper. In earlier contributions, we proposed an analytical model capable of predicting the magnetic pressure, radial velocity, and radial displacement for EMTC. In the present paper, our understanding of EMTC is expanded with the aid of a modified analytical model, a series of experimental tests with various materials, and 3D coupled electromagnetic-mechanical numerical simulations. First, the analytical model was improved by generating elements across the entire landing area of the field shaper. This modification provided a more accurate induced magnetic pressure in the analytical model. In addition, the experimentally measured coupling coefficients between the coil, field shaper, and workpiece tube were directly incorporated into the analytical model as opposed to utilizing them as correction factors during the magnetic pressure calculation in the previous studies. In the proposed analytical model, at each time increment, the magnetic field geometry is updated in response to the tube deformation. Second, to assess the proposed analytical model, experimental tests with Photon Doppler Velocimetry (PDV) were carried out for three different materials with different thermo-mechanical properties, i.e., Al6061-T6, Cu101, and Cu260 (Brass). Third, to compare the computational cost of the analytical model and to determine the accuracy of the proposed analytical model compared to the existing software packages in the market, a 3D coupled electromagnetic-mechanical finite element model was used. To investigate the influence of discharge energy on tube deformation, all three methods were examined at three different charging energies, i.e., 2.4, 3.6, and 4.8 kJ. Reasonably good agreement between all three approaches validates the ability of the analytical model to accurately capture the deformation velocity and displacement for this complex multi-physics manufacturing process in a computationally cost-effective manner. Such an analytical model can be used as a base model for predicting the impact velocity during electromagnetic pulse welding and crimping processes prior to performing expensive and time-consuming experimental tests or numerical simulations.

Analysis of field shaper materials on the deformation behavior of (AA6061) tube in electromagnetic forming process through simulation and experiments

Field shaper (FS) is an important tooling of an electromagnetic forming (EMF) systems. Therefore, FS materials and its geometry plays a crucial role in the effective forming and joining process of EMF systems. The materials used to fabricate FS should exhibit high strength and non-magnetic property with good conductivity. The cost of Electromagnetic manufacturing depends on the material of FS. In this study, the effect of various FS materials on process parameters was discussed. Properties such as conductivity, tensile strength and composition of material, were experimentally verified. Comparison of mechanical properties of different FS materials in terms of strength and performance have been analyzed. The electrical parameters, such as the inductance, resistance and Quality factor of FS materials experimentally measured. The factrography analysis of the failure of different FS materials have been carried out and the effect of EMF process parameters and their effect on the deformation of tubular workpiece have been analyzed. Finite element analysis (FEA) analysis was used to validate the experimental results of deformation with simulation to establish performance of FS materials. It was found that CuBe and CuTi alloy can be used as an alternative to Cu for fabricating FS with enhanced durability without compromising its performance.

Performance Measurements of Photodiodes for X-Ray Detection

The X-ray free-electron laser (XFEL) at the Pohang Accelerator Laboratory (PAL), Pohang, South Korea, provides X-ray energies of up to 15 keV depending on the experimental purpose. Silicon-based devices have been used as diagnostic devices and detectors for X-rays in experimental stations. Considering recent domestic and international circumstances, developing silicon-based detectors in-house is necessary. We developed a silicon p-intrinsic-n (PIN) photodiode (PD) for X-ray detection, and its performance was investigated and compared with that of a commercial PD used in the PAL-XFEL. The PD was designed to be 1 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times1$ </tex-math></inline-formula> cm in size, and it used the junction side for signal readout and the ohmic side for X-ray entrance. Considering the absorption length of 12-keV X-rays suitable for crystallography, a 500- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ {\mu }\text{m}$ </tex-math></inline-formula> -thick silicon wafer with a high resistivity was used for PD fabrication. It has a guard ring, an n+ edge field shaper, and an antireflection coating (ARC) and is available in four different types based on the metal structure of the junction and ohmic sides. We present here the electrical characteristics of the PDs. The depletion voltage at which the bulk of the PD is fully depleted was determined to be 119.7 ± 8.2 V from bulk capacitance measurements, and the operation voltage of the PD was set to 200 V. PDs with leakage currents less than 30 nA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at the operation voltage were chosen for performance measurements. The signal-to-noise ratio (SNR) with a Sr-90 radioactive source corresponding to the minimum ionizing particle (MIP) and the quantum efficiency (QE) for wavelengths of 300–1000 nm were measured. Beam tests were conducted at the PAL-XFEL using 600-, 900-, and 1200-eV X-rays where the responses to ultrahigh brightness and ultrashort X-ray pulses were checked. The energy resolutions were measured using gamma-ray radioactive sources, Am-241 (59.5 keV), and Ba-133 (31.0 and 81.0 keV). The differences in performance among the PD types are presented herein in terms of the electrical characteristics, SNR, QE, response to X-ray pulses, and energy resolutions. The results of the fabricated PDs were also compared with those of a commercial PD.

A study on the effect of process parameters on the joint strength and leak tightness in electromagnetically assisted adhesive Cu-SS tube-to-tube joining through statistical analysis

This work studies an improved hybrid joining technique combining electromagnetic forming and adhesive joining to create a leak-tight Cu-SS tube-to-tube joint named as electromagnetically assisted adhesive joining (EAAJ). An experimental investigation is performed considering three discharge energy (3.9 kJ, 4.4 kJ and 5.0 kJ), four adhesive application lengths (20 mm, 15 mm, 10 mm and 5 mm), three adhesives (Loctite 638, Loctite 567, and Loctite SI 596) and four curing times (24 h, 48 h, 96 h and 120 h) ad process parameters. The mechanical properties of the joints are investigated using testing techniques like pull-out, compression, and micro-hardness tests. An increase in joint strength is observed with the decrease in adhesive application length and increase in curing time. Maximum joint strength, 90% of the base copper tube strength, is obtained in the case of Loctite 638, with 5 mm of adhesive application length, 5.0 kJ of discharge energy and 96 h of curing time. Furthermore, a three-way analysis (3-way ANOVA) of variance technique is implemented to calculate the contribution of the three factors (discharge energy, adhesive application length, type of adhesives) on the joint strength. A cohesive and adhesive failure mode combination leading to sliding failure mode is observed as a joint failure mechanism during pull-out and compression testing. A leak testing setup has been developed to investigate the joint's leak tightness by an air pressure decay test. An increment in leak tightness by 1000 times is observed in 638 EAAJ samples compared to samples joined without adhesives. A 3-way ANOVA analysis is also performed to calculate the contribution of different factors on leak tightness of the joint. Micro-hardness is observed to be increased near the joint interface compared to the base metal. Deformation analysis has highlighted the impact of field shaper slit causing a non-uniformity in radial deformation in the circumferential direction and leading to non-uniform circumferential accumulation of adhesive.

Experimental and numerical investigations on electromagnetic powder compaction of Aluminium 6061 alloy powder

The present research's objective is to investigate the electromagnetic radial powder compaction process and its effect on the densification, microstructure and mechanical properties of the Al 6061 alloy powder. Cylindrical product has been prepared from Al 6061 powder using the electromagnetic powder compaction method. In this method, electromagnetic force shrinks the packing tube and utilises the deformation of the tube to compact the Al 6061 powder. The electromagnetic forces were generated between the field shaper's inner cylindrical surface and the outer surface of the packing tube when a high voltage current is flowing through the solenoid coil. In this study, the Al 6061 powder is compacted at various discharge voltages such as 13 kV, 14 kV, 15 kV and 16 kV using a 20 kV and 40 kJ capacity electromagnetic forming machine. Sintering is performed on the compacted samples at 620 °C for 1 h in an N2 tubular furnace. The simulation was carried out using loosely coupled multi-physics software, and simulated results were validated with the experimental results. Ansys Maxwell is used to analyse the electromagnetic field, and Ls-Dyna is used for structural analysis. To describe the deformation behaviour of the packing tube, the Cowper –Symonds model was used. The deformation in the compact and stress-strain variation was analysed using simulation results and experimental results. The effect of field shaper on powder compaction is investigated using the magnetic field analysis of the Ansys Maxwell results. The velocity of the packing tube is analysed for various input discharge voltages. The Vickers micro-hardness of electromagnetic powder compacted samples increases with compaction voltage. Finally, the results predicted by numerical simulation were verified with experimental results and found in good agreement.

Electromagnetic flanging using a field shaper with multiple seams

Electromagnetic flanging using a field shaper with multiple seams

Effect of field shaper tapered angle on the electromagnetic crimping of tubes on rods

Effect of field shaper tapered angle on the electromagnetic crimping of tubes on rods

Effect of field shaper tapered angle on the electromagnetic crimping of tubes on rods

Effect of field shaper tapered angle on the electromagnetic crimping of tubes on rods

The effect of assembly of coil and field shaper on electromagnetic pulse crimping

Electromagnetic pulse crimping (EMPC) technology is expected to be applied to the connection of high-voltage (HV) wiring harnesses and terminals for electric vehicle (EV). As an important part of the EMPC system, the assembly of the field shaper and the coil can directly affect the effect of EMPC. An EMPC system was established in this work, including the control part, energy storage capacitor bank, discharge switch, coil, and field shaper. The relationship between structure parameters of the field shaper and the coil was analyzed through the EMPC experiment of Al tubes. The results showed that the relative position and height of field shaper and coil have no obvious effect on the deformation length of the Al tube. When the angle between the gap of the field shaper and the gap of the coil is 90°, the deformation of Al tube is the most uniform. When the total height of field shaper is slightly less than the welding coil, the crimping effect is the best. This work can help design the field shaper and the coil for EMPC.

Improving the quality of Al-Fe tube joints manufactured via magnetic pulse welding using an inclined-wall field shaper

Due to the mismatched impact parameters between the velocity and the angle, a joint with an unbonded zone in the middle and the microdefects at the interface was fabricated by magnetic pulse welding (MPW). In this study, an oblique angle in the working zone was prefabricated to make an inclined-wall field shaper (FS) for MPW and thereby improve the quality of the joint. The effects of the span and size of the inclined wall on the impact parameters were evaluated by numerical simulations. With increasing span, the location where the maximum impact velocity occurred approached the free end of the joint. With increasing size of angle, the initial impact angle evidently increased. The microstructure indicated that the flat interface was changed into the wavy one, and the thick transition layer with microdefects could be removed using an inclined-wall FS. The double bonding zone was changed into the single one, which formed a continuous range with a length of above 3 mm where the impact parameters matched with each other. The length of the unbonded zone in the initial collision zone decreased from about 1 mm to 0.3 mm via using an inclined-wall FS with the span of 6.4 mm and the size of 5°. Shear test results showed that the zones with high strength were merged in the initial collision region. The maximum shear strength of about 81 MPa could be obtained using an inclined-wall FS with the size of 3° and the span of 6.4 mm, which was increased by 33% higher than that without an inclined wall.