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The armature is an important part affecting the energy conversion efficiency of a reluctance accelerator. In this paper, six kinds of soft magnetic materials are chosen and four structures are designed for the armature. At first, the circuit and magnetic force are theoretically analyzed. Then the armatures with different materials and structures are used in the simulation, and the performances are compared and analyzed. At last, the experiment verifies the theory analysis and simulation design. It is concluded that the saturation flux density and conductivity of the material are the key factors affecting the armature force, and the optimization of armature structure can effectively restrain the eddy current, reduce negative force and improve efficiency. Compared with cutting slits in solid armatures, laminating the sheets radially can reduce the eddy current more efficiently. Although slitting can prevent the eddy current to a certain extent, meanwhile, it will decrease the magnetic force because of the losing of magnetized volume and the surface area. Hence, choosing the high saturation flux density material and making out the armature with radially_laminated sheets will improve the efficiency of the reluctance accelerator. In this paper, the silicon steel radially_laminated armature is a better choice for the armature design of the reluctance accelerator.

Bu çalışmada, çelik üzeri alüminyum kaplanmış (ACS: Aluminum Clad Steel) tel olarak nitelendirilen iletken tellerin tahribatsız muayene sürecinde kullanılmakta olan çevreleyici bir prob tasarımı yapılmıştır. İletken materyallerin üretim ve kalite kontrol süreçlerinde tahribatsız muayene yöntemlerinden olan girdap akımları sistemleri yaygın bir şekilde kullanılmaktadır. Bu sistemlerde, materyal türüne bağlı olarak farklı tipte probların tasarlanması ve kullanılması mümkündür. Boruların, tellerin ve plaka şeklindeki iletken materyallerin muayenesi için sırasıyla dahili, çevreleyici ve yüzey prob türleri kullanılmaktadır. Bu problar ile iletken yüzeylerindeki süreksizlikler tespit edilip, proba ait bobinlerin indüktans değerlerinde meydana gelen değişiklikler elektronik donanımlar ile analiz edilerek materyalin kalite kontrolü sağlanmaktadır. Bu çalışmada, tel yüzeylerindeki çeşitli kusurların algılanabilmesi için hassas bir prob tasarımı gerçekleştirilmiştir. Tasarlanan proba ait indüktans değerleri, iki ve üç boyutlu sonlu elemanlar analizi (SEA) kullanılarak hesaplanmış ve elde edilen bu değerler karşılaştırılmıştır. Proba ait indüktans değişimi, içerisinde farklı türden kusurlar içeren numune ACS teller varken bir LCR metre vasıtasıyla ölçülmüş, bu değerler tabloda verilmiş ve değişim grafiği çizdirilmiştir. Aynı zamanda, prob ile bir empedans köprü devresi kurularak bobin üzerinde meydana gelen voltaj indüklenmesindeki değişim sonuçları osiloskop çıktısı olarak verilmiştir., In this paper, an encircling probe design used in the inspection of conductive wires, which are qualified as aluminum clad steel (ACS) wire is made. The eddy current systems are widely used for the quality control of conductive materials as one of non-destructive testing methods. In these systems, it is possible to design and to use different types of probes according to the material type. Internal, encircling and surface probe types are used for the inspection of pipes, wires and plate conductive materials, respectively. The discontinuities on the conductor surfaces are detected and the changes in the inductance values of the coils of probes are analyzed with the electronic hardware and the quality control of the material is ensured. In this study, a sensitive probe design is realized to detect various defect on wire surfaces. The inductance value of the designed probe is calculated by using two and three dimensional finite element analysis (FEA) and the obtained results are compared. The inductance change of the probe was measured by an LCR meter while the probe contained sample ACS wires with different types of defects, these values are given in the table and the change graph is plotted. In addition, an impedance bridge circuit was set up with the probe and the results of the change in voltage induction on the coil are given as an oscilloscope image.

The problem of reducing magnetic losses (no-load losses) in the steel of the magnetic cores of electrical machines is investigated. The tasc of determining the optimal thickness of steel sheets of the magnetic circuit of an electric machine is considered. The criterion for optimality is the minimum power of magnetic losses in steel. Currently, this problem does not have an exact solution due to the fact that the exact ratio of the hysteresis and eddy current components of magnetic losses in steel is unknown. Analyzed the power of magnetic losses in modern electrical machines and devices, depending on the thickness of the sheets of electrical steel. A method is proposed for determining the optimal thickness of steel sheets of the magnetic circuit of an electric machine based on the wattmeter method. In the course of the experiment, two identical magnetic circuits were selected from steel sheets of different thicknesses, for which the losses in steel were measured at different frequencies of magnetization reversal and the optimal thickness of the sheets was calculated. The proposed formula for calculating the thickness of the sheets is valid for both isotropic and anisotropic steel. The proposed technique can be used for both transformers and electric motors and generators.

It is still a big challenge to calculate the probability of defect detection for inspecting pits on austenitic stainless steel welding using traditional POD models. Because we determine the decision threshold, the POD curve has a lot of changes as the decision threshold changes, there is no clear reason to insist which threshold is reasonable. This study proposes a new probability of detection (POD) model to quantitatively assess the detection capability of eddy current probes for inspecting pits on austenitic stainless steel welding. The experimental results show that the proposed model is more reasonable than traditional ones. The novel POD model was employed to analyze three eddy current probes, uniform, TR, plus-point probes on austenitic stainless steel welding. The results reveal that the uniform eddy current probe has the best detection capability for inspecting pits on among the three probes.

The continuous eddy current pulse treatment (ECPT) combined with heat treatment was employed to heal the microcracks in spin formed Mg alloy tubes and improve their mechanical properties in this study. The results show that all the microcracks in different tube specimens were almost healed after different continuous ECPT schemes up to 15 cycles. The schemes with less cooling intervals exhibited better healing effect and increased the strength and elongation of Mg alloy tubes more obviously. After aging treatment, the strength improvement of the specimens with ECPT was more remarkable than that of the specimens without ECPT, and the elongation decrease of the specimens with ECPT was less evident than that of specimens without ECPT due to the segregation of RE elements on the crack surface. Besides, after solution treatment, the strength reduction and ductility improvement of the specimens with ECPT were more pronounced than that of the specimens without ECPT owing to the notable decrease of dislocation density of the specimens with ECPT. Both narrowed cracks induced by ECPT and the segregation of precipitates in the vicinity of microcrack surface during aging treatment contributed to the maximum strength in the as-spun specimens with ECPT followed by aging treatment.

In this study, we explore the vector magnetic properties of the electrical steel sheet under dc-biased flux and rotating magnetic field of different frequencies. The corresponding iron loss and the rotational eddy current loss are discussed. An enhanced vector magnetic hysteresis model is proposed to describe the $B$ – $H$ behavior under these conditions. The accuracy of the proposed model is verified by the close agreement between the hysteresis loops calculated with the proposed model and those measured experimentally, as well as by the neglectable calculation error of the total iron loss.

This article proposes a novel analysis method for the losses in a litz wire considering the circulating and eddy currents. In the proposed method, the macroscopic complex permeability is introduced to evaluate the eddy current loss owing to the proximity effect. Homogenization-based finite element analysis using the macroscopic complex permeability can effectively compute the proximity effect loss. The loss owing to the circulating currents is evaluated by solving the corresponding circuit equation. It is shown that the eddy current loss is dominant for the solenoidal and spiral coils without magnetic cores because of the uniform magnetic field distribution along the wire. Moreover, the magnetic reactors in which the circulating current loss cannot be ignored are analyzed using the proposed method. It is shown that the losses computed by the proposed method agree well with the measured results.

The soft magnetic performances including frequency-dependent permeability, core loss, and DC-bias properties of the Fe-6.5 wt.%Si (FeSi) soft magnetic composites (SMCs) coated with different contents of NiZn-ferrite and compacted with different forming pressures were compared and analyzed. The retained permeability at an applied field of 7960 A/m has a proportional relationship to the real part of complex permeability, which is observed to be closely related to cores’ bulk density. A three-dimensional loss separation model and its related fitting analysis on the domain walls and magnetic objects were established to investigate the relative loss mechanism for the FeSi SMCs fabricated under different parameters. The variation of total core loss (Pcv) is mainly induced by the changes of hysteresis loss (Ph) and excess loss (Pexc) with different fabrication parameters, wherein both the Ph and Pexc are sensitive of the number of pinning site that inhibits the motion of domain wall. The inter-part eddy current loss is only 1/600–1/250 of total core loss for all the ferrite-coated SMCs owing to the relatively high electrical resistivity of 1.22–2.8 Ω m. These results offer an in-depth observation into regulating the comprehensive soft magnetic properties of the SMCs coated with magnetic insulating layer for high-frequency and high-power applications in electromagnetic components.

Soft magnetic composites (SMC) with a bionic shell structure and a delicate, regular layered arrangement were prepared via a casting process. The permeability of composite samples was 140 at 5 MHz for plane anisotropy, while that of the spherical-particle-constructed material is only 14. According to classical loss separation results, the layered bulk material without an SiO2 coating exhibited lower hysteresis loss. In contrast, the layered bulk material coated with SiO2 showed lower eddy current loss, attributed to the increase in resistivity resulting from the SiO2 coating. The magnetic loss of the layered bulk materials was 588 kW/m3 at 50 mT and 100 kHz. SMC materials with this structure are anticipated to have strong potential for magnetic cores used in high-efficiency power supplies.

FeSiAl/SrFe12O19 composites with different SrFe12O19 contents were prepared, and their microstructure magnetic properties were studied. It can be seen from the SEM morphology picture that the SrFe12O19 powder is relatively fine, filling the gaps between the FeSiAl spherical particles. The SrFe12O19 ferrite has a higher resistivity than FeSiAl alloy and can be used as an insulating agent. Hysteresis loop results show that the saturation magnetization of all composites is relatively high (up to 163 emu/g). Magnetic loss analysis shows that the hysteresis loss increases with the increase in the SrFe12O19 content, which may be caused by the high anisotropy of SrFe12O19 powder. The eddy current loss is the smallest when the SrFe12O19 content is 10.7 wt%. Our research illustrates that proper addition of SrFe12O19 content can reduce eddy current loss and SrFe12O19 can be used as an insulating agent for soft magnetic composites.

In order to calculate the iron loss in motors with high accuracy, it is necessary to consider skin effect of the eddy current in laminated electrical steel sheets. To solve this problem, the post 1-D analysis is used. It divides every element along the thickness and calculates the distribution of the eddy current and magnetic flux density. In this article, we propose improved post 1-D analysis using the distribution of the differential permeability. In this method, 1-D equation has second differential term using differential permeability coefficient. By using the differential permeability, it is possible to express the sensitivity of the magnetization correctly.

This article presents an algorithm for identification of anomalous magnetic field and loss in silicon steel sheet (SSS). Since the magnetic field in an SSS consists of static hysteresis, eddy current, and anomalous magnetic fields, the anomalous magnetic field is extracted from the measured hysteresis field by excluding the static hysteresis and eddy current fields. In order to predict the anomalous magnetic field for an arbitrary $B$ -waveform, an artificial neural network model with deep learning algorithm is suggested. Through comparisons with experimental measurements over a non-oriented electrical steel sheet, 35PN440, the proposed algorithm is validated.

Eddy currents induce velocity errors (veddy) that influence PC-MRI derived parameters; static tissue corrections aim to minimize these veddy influences. Local and global static tissue corrections have been proposed; however, these separate strategies have yet to be thoroughly characterized. The dependence of local and global static tissue corrections on SNR and the amount of static tissue used for correction is not well understood. To characterize these relationships, corrections were analyzed within a static phantom and flow phantom experiment. Corrections were repeated for a range of SNR and for increasing amounts of static tissue used for polynomial fitting. Local and global corrections were separately applied to reduce velocity offset within ROIs within a static tissue phantom. Global correction reduced velocity offset in 100% of ROIs and local correction reduced velocity offset in ~96% of ROIs. Local correction introduced error in ~4% of ROIs (always when SNR < 30). Correction differences between local and global strategies in the static phantom experiment were on the order of 0.9 cm/s for low SNR protocols and 0.2 cm/s for high SNR protocols. Velocity offset within static ROIs was reduced by up to an additional ~0.6 cm/s by increasing static tissue coverage for low SNR protocols (~0.05 cm/s for high SNR protocols). Local and global corrections were separately applied to correct total volumetric flow estimates within a flow phantom. Veddy errors induce differences between total flows measured at different locations along a flow phantom. Static tissue corrections reduced these differences between total flow estimates in 90% of corrections. Of these cases, global correction provided a larger reduction in flow difference ~67% of the time. Local fitting introduced error in ~27% of total corrections, and errors were observed for a range of SNR. Global fitting introduced one instance of error (for lowest SNR). Flow differences were reduced by up to an additional ~2 mL by increasing static tissue coverage. This study indicates that: 1) Local static tissue correction is suitable only for higher SNR PC-MRI applications and 2) Maximizing the amount of static tissue used during polynomial fitting improves performance of applied corrections for low SNR applications.

Sensors for structural health monitoring (SHM) need to be permanently integrated on structures and withstand the harsh service environments, which has been a big challenge for the application of SHM in aircrafts. This paper focuses on the durability of flexible eddy current array (FECA) sensors in harsh service environments of aircrafts, including vibration environment and several typical exposed environments. First, a kind of FECA sensor is illustrated and its integration method is proposed. Moreover, in order to study the durability of the sensor in vibration environment, the modal analysis is performed by the finite element method. According to the simulation results, the durability experiment in vibration environment is carried out under the fourth order vibration mode, which makes the sensor suffer the harshest vibration loads. During the vibration experiment, output signals of the sensor keep stable and the sensor is well bonded to the structure, which shows the integrated sensor has high durability in vibration environment. Finally, the durability of integrated sensors is separately tested in three exposed environments, including salt fog corrosion environment, fluid immersion environment, as well as hygrothermal and ultraviolet-radiation environment. After these environmental exposure experiments, all sensors are well bonded to structures and can effectively monitor fatigue cracks, which shows great durability. Therefore, FECA sensors can survive in harsh service environments of aircrafts, which provides important support for the engineering applications of FECA sensors.

Litz wire has been widely utilized in power transformers and inductors as a wire with low copper loss at high-frequency operation. The Litz wire is commonly made of many thin isolated strands twisted in multiple levels. Due to its complicated structure, the copper loss prediction of the Litz wire has been difficult, hindering the design optimization of the Litz wire structure. To overcome this difficulty, preceding studies have investigated the analytical copper loss models of the constituting elements of the Litz wire, i.e., the strands and the bundles of strands. The purpose of this article is to propose an analytical copper loss model of the Litz wire by utilizing these preceding knowledge. The proposed model is formulated only with parameters that can be measured by basic testing instruments. Besides, the proposed model considers the bundle structure of the Litz wire, which affects the local ac current distribution, and the twisting pitch, which causes the inclination of the Litz wire strands. The proposed model was tested by comparing the analytical prediction and experimental measurements of the ac resistance of commercially available Litz wires. As a result, the predicted ac resistance showed good agreement with the measured ac resistance, suggesting the appropriateness of the proposed model.

Fe-based soft magnetic composites (SMCs) co-coated with Bi2O3 and silane, used as the low melting point binder and the insulating layer, respectively, were successfully prepared. The SMCs show improved mechanical strength, thermal stability, and insulation compared to other soft magnetic composite materials. The obtained SMCs exhibit a high Bm of 1.2607 T at 5000 A/m, 50 Hz, a high μmax of 497, and a low Pcm of 81.8 W/kg at 50 kHz and 50 mT for a completely homogeneous thin insulating coating. In addition, the transverse rupture strength of such materials is up to 81.2 MPa, which is extremely important for high-speed motors. Furthermore, the permeability and magnetic loss are stable under stress. Nonlinear curve fitting was used to build the loss model and then separated into the hysteresis loss, the eddy current loss, and the excess loss. The loss mechanism of SMCs with different coatings and micro-stress was explored and verified via this model. When compared to traditional SMCs, this material coated with Bi2O3 and silane shows a lower loss and a higher transverse rupture strength. This research expands the application fields of iron-based SMCs, especially in practical applications of soft magnetic components in high-speed motors.

Magnetic materials, as a key component used in electrical equipment, directly determine the equipment performance. The total core loss formula derived by the Poynting vector represents the flow of electromagnetic energy through a closed surface, but it does not include the energy consumption of heat due to eddy current. Also, the permeability of magnetic materials is not uniform in the period of magnetization, even for isotropic materials. This study derives the electromagnetic energy formula considering tensors of permeability and permittivity, and the modified total core loss formula is given. The formula contains three components. The first component is the modified form of the Poynting vector, the second component is the expression of eddy current loss, and the third component is the loss between the axial directions under rotational magnetizations. The experiments of nonoriented silicon steel B35A210 at 20, 50, 100, and 200 Hz are carried out on a 2-D magnetic properties measurement system. The experimental results are compared with the theoretically derived results to understand the eddy current loss and hysteresis loss.

In this article, multifrequency eddy current testing is proposed to detect hydrogen concentration in alloy titanium. The effect of hydrogen on the titanium alloy was explored across the surface layer of the material. The sample has a fixed surface area, and the samples with the same thickness and different hydrogen concentrations are analyzed. Output voltage amplitudes and dielectric loss tangent in hydrogen-filled titanium VT1-0 were studied in the range of hydrogen concentration from 0.019 to 0.290 wt.% using the instrument Micromagnetic Multiparameter Microstructure and Stress Analysis (3MA-II) at the frequency from 200 to 1000 kHz. This article proposes a method of analyzing the internal conductivity of metals by eliminating surface effects. The linear relationship between hydrogen concentration and conductivity is obtained, and the experimental results that are closer to the theory than the four-probe method and the inclusion surface are obtained. The results show that the output signal amplitudes decreased with an increase of the hydrogen concentration and frequency, and in addition, the dielectric loss tangent obtains a similar result at the hydrogen concentra- tion >0.100 wt.%. It is shown that this method can be used to evaluate the concentration of hydrogen in metal.

Spinel ferrites are very popular due to their large flexible properties and loss eddy current loss. Among spinel ferrites, Ni-Zn nanoferrites plays vital in industry because of its numerous applications in r due to its high permeability and high mechanical strength. Ni – Zn are very good magnetic materials and its magnetic, electrical and structural properties can be varied by changing ions at tetrahedral and octahedral sites. Ni-Zn nano ferrites papers were studied and summarized the conclusions of different studied by varying synthesis methods, varying shape of nanomaterials, changing dopant, changing sintering temperature and changing annealing temperature.

The nonferromagnetic pans with a low equivalent resistance are desired to generate sufficient power for heating by larger eddy current. First, Maxwell 3D is used to estimate the equivalent heating resistance of a copper pan and select the optimal number of turns for a induction coil by Litz wire according to its size limitations and efficiency. Furthermore, the optimal resonant frequency is determined by maximizing the heating efficiency. Finally, the electric parameters are obtained to construct a simulation environment for the design of control strategies. A full-wave rectifier, buck converter, and half-bridge resonant converter are cascaded to construct the converter. Because of low equivalent resistance and high quality factor of the copper pan, a high slope ratio of the resonant current to the frequency is obtained. Therefore, the resonant converter is operated at a fixed switching frequency to reduce low-frequency oscillations of the resonant current. The buck converter is used to control the DC link voltage with third-harmonic injection, which enables heating power control, increases heating power and satisfies the standard, IEC-61000-3-2 Class A. Moreover, a resonant frequency estimator is developed to detect the resonant frequency for various positions of the pan on the induction coil to determine the optimal heating frequency. Finally, TMS320F28075-based converter with 100 A of peak resonant current is built. The heating effect and power loss on a copper pan is then measured, and the maximum heating efficiency is 69%. The measurement results verify the effectiveness of the proposed induction cooker and exhibits excellent agreement with the simulated results.

This paper provided a method to improve the conversion efficiency and lessen the lift-off effect of spiral coil electromagnetic acoustic transducer (EMAT) for some specific situations, for example, irregular sample surface, online inspection and varying coating. Moreover, a new evaluation method for the performance of EMAT is proposed. To study the effect of the structural parameters on the performance of EMAT, the orthogonal test method with five factors and four levels is employed. Consequently, the degree of five factors on the lift-off performance and the theoretical maximum value of amplitude are obtained. The results show almost all factors have an obvious impact on the theoretical maximum value of amplitude, while only the magnet-to-coil distance can affect the lift-off performance effectively. The experiment results well agree with the numerical results, in which the improvement of the lift-off performance and the theoretical maximum value of amplitude is 31.94% and 78.79% respectively. In addition, the conversion efficiency of EMAT is increased by 125% when the lift-off is 1 mm. These imply the performance of spiral coil electromagnetic acoustic transducer is improved dramatically and the detectable lift-off is increased as well.

When studying transients in pulsed current traction motors, it is important to take into consideration the eddy and hysteresis losses in engine steel. Magnetic losses are a function of the magnetization reversal frequency, which, in turn, is a function of the engine shaft rotation frequency. In other words, magnetic losses are a function of time. Existing calculation procedures do not make it possible to derive the instantaneous values of magnetic losses as they are based on determining average losses over a period. This paper proposes an improved model of magnetic losses in the steel of a pulsed current traction motor as a function of time, based on the equations of specific losses. The adequacy criteria of the procedure for determining magnetic losses in electrical steel have been substantiated: the possibility to derive instantaneous values of magnetic losses in the magnetic material as a function of time; the possibility of its application for any magnetic material; and the simplicity of implementation. The procedure for determining magnetic losses in the steel of a pulsed current traction motor has been adapted by taking into consideration the magnetic properties of steel and the geometry of the engine's magnetic circuit. In order to determine the coercive force, the coefficient of accounting for the losses due to eddy currents, as well as the coefficient that considers the losses on hysteresis, the specifications' characteristics of specific losses in steel have been approximated using the pulsed current traction motor as an example. The simulated model of magnetic losses by the pulsed current traction motor has demonstrated the procedure for determining average magnetic losses and time diagrams of magnetic losses. The proposed model for determining magnetic losses could be used for any magnetic material and any engine geometry under the condition of known material properties and the characteristics of change in the magnetic flux density in geometry

The aim of this research is to prove that when a current carrying cable is sized sufficiently to carry a large current and is placed in a steel pipe, the main energy loss is eddy current and not joule heating or I2R loss. To prove this, two methods were used to negate the eddy current which are by placing live and neutral cables in the same pipe and the other was to place the same cable in HDPE pipes where eddy current cannot be induced. It was conclusively proved that eddy current was the main generator of heat. Heat was also observed all over the circuit and it was discovered that joints had the most heat. Finally, the steel pipe itself was made part of another circuit to attempt to drain off the induced eddy current but this did not prove effective.

Due to uneven surface and lift-off effect, it is difficult to detect weld crack by eddy-current testing. A new orthogonal eddy-current probe for weld crack detection of carbon-steel plate was designed in this paper. Based on COMSOL Multiphysics, the influence of scanning angle on detection sensitivity of the probe was compared firstly. Then, the effects of coil width, coil side length, detection coil height, and lift-off distance on detection sensitivity of the probe were studied, respectively. Finally, the test piece of carbon-steel plate weld with crack, and the physical probe used to verify the crack detection effect were made. The experimental results show that the weld crack of carbon-steel plate with length × width × depth of 20.0 mm × 0.3 mm × 1 mm can be effectively identified, and the lift-off noise can be effectively suppressed by the method presented in this paper. At the same time, the signal-to-noise ratio of the probe keeps constant in the lift-off distance range of 0.3 mm–3.0 mm.

This study proposes a method to probabilistically evaluate the area of coverage of nondestructive inspections to detect defects on a surface of a structure. For the specific problem, this study considers the effect of the distance between two neighboring scanning lines on the detectability of eddy current testing against near-side cracks. Thirty-eight type 316L stainless steel plates having a fatigue crack were prepared, and eddy current examinations were performed with a sufficiently fine scanning pitch. The full width at half maximum of the spatial distribution of the amplitude of the signals was approximated using a Gaussian function. A probability of detection model considering the distance between two neighboring scanning lines is proposed because in actual inspections a scanning line does not always run directly above a crack. The results demonstrated that the proposed model enables a reasonable probabilistic evaluation of the effect of the distance between two neighboring scanning lines.

Aluminum alloys are commonly used in commercial aircraft due to their low density and excellent mechanical properties. However, they need to become increasingly competitive in order that aluminum plate manufacturers maintaining market share. One way to ensure this is to improve or control parameters used in heat treatments. It is well known that electrical conductivity of metal alloys varies with microstructural change. Therefore, it is believed that In-Situ control of microstructural evolution can lead to optimization of treatment time, reduced energy consumption, increased production and final product quality, as well as reduction of costs, nonconformities and rework, having low implementation cost. In this way, eddy current sensors can be coupled to the furnace controller to optimize time and quality of heat treatment through the analysis of electrical conductivity with low implementation cost. Therefore, the objective of this work is to design, model and validate an eddy current sensor to monitor heat treatment of precipitation hardenable aluminum alloys in real time. Samples of 2024 alloy were prepared by solution treatment at 495 °C for 3 h and monitorization of aging treatment was performed at 190 °C for 9 h. Hardness, metallography, electrical conductivity (outside furnace) and relative electrical conductivity (inside furnace) were analyzed. The results were compared with the literature. There is a lot of discrepancy in the results of other authors. The eddy current sensor showed that behavior is similar to electrical conductivity through four-terminal method outside furnace.

In the conventional electromagnetic forming processes, the Lorentz force is induced by the eddy current in the specimen, so the coil should be specifically designed to form the electrical current return. Here, a novel electromagnetic forming method is suggested for aluminum alloy strip or profile, in which the inverse current is imposed instead of eddy current to generate Lorentz force. As an electromagnetic actuator, a very simple strip of copper was connected in parallel with the aluminum alloy strip. When the impulse currents flowed synchronously along the opposite directions between the copper and aluminum alloy strips, the Lorentz force was generated to deform the aluminum alloy strip. The electromagnetic forming of AA5754 aluminum alloy strip by imposing inverse current was investigated by numerical simulation. It was finally validated by comparison with the experimental results.

Faraday shields are widely used in high-frequency transformers to conduct the common-mode (CM) current to the ground. They are normally located in the high magnetomotive force (MMF) region, where severe eddy currents are induced and contribute considerable magnetic field losses. In this article, an analytical procedure is presented for the magnetically-induced loss in Faraday shields. It is originally derived from shields of foil conductors. Then, it is extended to different shields with round and Litz wire, and different configurations, e.g., multilayer shields, interleaved windings, and coaxial transformers. It is verified by the finite element method (FEM) and experimental results in six case studies. Moreover, the criteria to determine the losses of Faraday shields is given and a design procedure is presented to reduce the shield losses at a certain level while keeping the functionality. Finally, a case study is provided to verify the shield design procedure on a 100-kHz transformer.

Thin metallic coatings are used in a wide range of industrial settings to protect or enhance the properties of the underlying material. We propose a new swept-frequency eddy-current-based technique to simultaneously measure the thickness and conductivity of metallic coatings, which thickness in the order of tens of micrometers. Variations in coil impedance with lift-off were discussed when the coil was placed above a conductive plate with and without a thin metallic coating. Then, an impedance coordinate transformation method was presented to eliminate the lift-off effect. In the new impedance coordinate system, the impedance of the coil placed above the plate under testing was normalized by the impedance of the coil placed above two reference plates to form a new model containing the variables that are the coating thickness and conductivity, and the conductivity of the underlying plate. A combination of the least-squares method and the Levenberg–Marquardt (LM) algorithm was applied to solve it. The proposed method can be extended to measure the parameters of a conductive plate with multilayer metallic coatings. The results of the experiments in this study showed the proposed method has high accuracy and sensitivity.

The application of high-temperature superconductors to accelerator magnets for future particle colliders is under study. Numerical methods are crucial for an accurate evaluation of the complex dynamical behavior of the magnets, especially concerning the magnetic field quality and thermal behavior. We present a coupled $\textbf{A}$-$\textbf{H}$ field formulation for the analysis of magneto-thermal transients in accelerator magnets. The magnetic field strength $\textbf{H}$ accounts for the eddy current problem in the source regions containing the superconducting domains, while the magnetic vector potential $\textbf{A}$ represents the magnetoquasistatic problem in the normal and non-conducting domains. Furthermore, we include a slab approximation for the source regions, making the formulation suitable for large scale models composed of thousands of tapes. In this work, the relevant equations are derived and discussed, with emphasis on the coupling conditions. The weak formulation is derived, and numerical results are provided in order to both, verify the formulation and scale it to the size of an accelerator magnet., Comment: 10 pages, 11 figures

Iron loss prediction is extremely crucial to performance and thermal analysis for high-speed permanent-magnet (PM) machines, but it is difficult to conduct at arbitrary frequency especially high frequency. Due to the frequency-dependent coefficients of iron loss model, although iron loss can be calculated by loss model with constant coefficients under fixed frequencies, it is not feasible to measure the required loss data of non-oriented electrical steel under each frequency. Moreover, toroid tester is better to obtain accurate loss data of steel, but the data under specific high frequency cannot be directly measured due to the limitation of equipment and tester. Thus, this study presents a three-term iron loss model with variable coefficients to predict iron loss of machines at arbitrary frequency, especially high frequency based on measured loss data of steel at low frequency. Although both proposed three-term model and conventional two-term model with variable coefficients can predict iron loss of machines at an arbitrary frequency, the comparison shows that the accuracy of the three-term model is higher. In addition, experiments validate that proposed three-term model with variable coefficients is accurate and feasible for iron loss prediction in high-speed PM machines.

For the high-speed permanent magnet synchronous motors (HSPMSMs), their magnetic fields are more complicated with the rotating magnetization and harmonics considered. Furthermore, there are interaction effects on motor iron loss from high frequency, temperature, and compressive stress. In order to obtain the accurate HSPMSM iron loss calculation model, different iron loss models are proposed, in this article, considering these physical factors, and the iron loss model considering the interaction effect of the multiphysics factors is given. The magnetic field, temperature field, and stress field are analyzed for HSPMSM by finite-element method (FEM). Then, the proposed models are employed to calculate the iron loss of the silicon steel sheet and the prototype. The accuracy of the proposed iron loss model, which can consider the interaction effect of the multiphysics factors, is verified by the experimental test measurements on the prototype.

The electro-erosive wheel dressing exerts a significant impact on the machining accuracy of an article and the efficiency of the profile grinding process. To effectively control machining accuracy, the most important is the error due to the wear of a diamond wheel. The wheel should be dressed when wear approaches to the border but does not go beyond the tolerance field. This would reduce the number of defects at machining and bring down the utilization of diamonds. In addition, this reduces the dressingtime and, therefore, improves the efficiency of profile diamond grinding. The paper reports the methodology and results of an experimental study into the wear of profiled diamond wheels. The specific utilization of diamonds was examined on the grinding wheels of the direct profile. The amount of a wheel linear wear was measured by a contactless method applying a special device based on the use of eddy current sensors. This was followed by determining the integrated amount of the worn volume of a diamond layer; after that, the weight of the used diamonds was measured. The mass of the sanded material was determined by weighing it before and after machining. A mathematical method of planning and analysis of experiments was used to establish the functional dependence of the specific utilization of diamonds on the technological machining modes and the diamond layer parameters. The result of regression analysis is the derived functional dependence of diamond specific utilization on the following factors: the concentration of diamonds in a wheel, the grit of the tool, the grinding wheel velocity, the depth of grinding, and the speed of an article. To determine the patterns of wear of the shaped diamond wheel, we received an imprint of its profile on a control plate made from a solid alloy and measured the coordinates of the points of the working part of the profile relative to the non-utilized areas. Determining the difference of coordinates before and after the experiment has helped find the amount of radial wear of the grinding wheel at the appropriate profile point

The article deals with the issue of non-destructive testing of riveted joints. In the article, the authors used a non-destructive eddy current array technique, which was applied to detect simulated corrosion in the field of aircraft riveted joints of aluminum sheets. In aircraft maintenance, the eddy current method is used to control the outer surface of the aircraft skin, especially the areas around the riveted joints. This method makes it possible to detect hidden cracks and corrosion that may occur during aircraft operation. Especially hidden are hidden cracks and corrosion of aircraft structures, which cannot be detected during a visual inspection of the aircraft. The aim of the experimental measurements was to reveal simulated corrosion in the area of riveted joints formed on the experimental sample. Corrosion was simulated by gluing aluminum powder to the surface of the aluminum sheets from which the sample was made. The simulated corrosion in the second and third layers of the riveted sample was reliably detected. The settings, the method of control and the results of measurements are given in the article in the experimental part and the results of measurements. Measurements were performed using a defectoscope with an ECA measurement module, with appropriate measuring probes suitable for this type of inspection.