International Journal of Applied Electromagnetics and Mechanics - Volume 55, issue S1

Authors: Cheng, Zhiguang | Zhu, Jianguo | Li, Yongjian | Sievert, Johannes

Article Type: Research Article

DOI: 10.3233/JAE-172251

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. S1, pp. 1-, 2017

Authors: Moses, Anthony J.

Article Type: Research Article

Abstract: This paper is intended to stimulate discussion of some effects of not properly accounting for material microstructure in some established methods of measurement and prediction of losses in electrical steel laminations. Aspects of methods which have been used for many years are briefly discussed and some constraints or pitfalls are raised which users should be aware of. The basic cause of losses is summarised in order to set the scene for discussion of the analysis of losses into classical eddy current, hysteresis and anomalous loss. The possible presence and consequences of transverse flux in grain-oriented (GO) steels is raised followed …by an explanation of some effects of the strong anisotropy of GO steel on flux density, magnetic field and loss measurement in stacks and single strips of GO steel. The presentation concludes with some questions on how circular rotational magnetisation can be made and precautions needed when assessing the effect of flux harmonics on the losses. Show more

Keywords: Electrical steel, losses, grain-oriented silicon iron, anisotropy

DOI: 10.3233/JAE-172252

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. S1, pp. 3-13, 2017

Authors: Gao, Yanhui | Eguchi, Yuto | Ebrahimi, Hassan | Dozono, Hiroshi | Muramatsu, Kazuhiro | Guan, Weimin | Yuan, Jiaxin | Tian, Cuihua | Chen, Baichao

Article Type: Research Article

Abstract: In this paper, numerical techniques for simulation of magnetic domain structures of ferromagnetic materials using micromagnetics with large cells are investigated to save the computation cost. The exchange energy is modified to be applicable to large cells considering the angle between two neighboring cells. The demagnetizing energy is also modified to take account of erroneous magnetic surface charges which appear around the domain walls as a result of discretization. The method is then applied to a simple model and the result shows that an ideal vortex magnetic domain structure and domain wall motion can be represented.

Keywords: Magnetic domain, micromagnetics, exchange energy, demagnetization energy

DOI: 10.3233/JAE-172253

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. S1, pp. 15-21, 2017

Authors: Leuning, Nora | Steentjes, Simon | Hameyer, Kay

Article Type: Research Article

Abstract: The Villari Effect (inverse magnetostrictive effect), which describes the sensitivity of magnetic properties of ferromagnetic materials to mechanical stress is pivotal for actual operational characteristics of electrical machines. In rotating electrical machines mechanical stress is inevitable. It is inherent in processed parts from processing and manufacturing as well as induced by operation of the machine (e.g. centrifugal force). Consequently, magnetic behavior of non-oriented (NO) electrical steel (ES) needs to be characterized not only in its unstressed state as determined by standardized testing, but also considered with regard to its stress dependency. Due to non-uniform distributions of crystallographic orientations within the …material, interdependencies between stress and occurring anisotropies have to be identified in order to explain magnetic properties in the entire sheet plane of NO laminations. In this paper the effect of tensile and compressive stress on the magnetic properties of a conventional 2.4 wt % Si electrical steel is studied. Particular attention is paid to the comparison between different directions of applied mechanical stress with respect to the rolling direction. Therewith, the initial anisotropy and interrelating effects due to mechanical stress are evaluated. Show more

Keywords: Electrical steel, hysteresis, mechanical stress, plastic deformation

DOI: 10.3233/JAE-172254

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. S1, pp. 23-31, 2017

Authors: Ren, Yajun | Zhang, Yanli | Gong, Yuan | Zhang, Dianhai | Ren, Ziyan | Xie, Dexin

Article Type: Research Article

Abstract: A magnetostriction single-sheet tester with an air compressor was developed and the magnetostriction in an electrical steel sheet was measured by a triaxial strain gauge under applied stresses externally and higher harmonic of field. The magnetostriction property’s sensitivity on the applied stress was described. This investigation also tried to understand the relationship between the presence of higher harmonics in the magnetization waveform and those in the magnetostriction waveform under a certain stress. The study results for the magnetostriction under stresses and harmonics show that the appearance of harmonic of magnetic field cannot be ignored, which aggravates the principal strain harmonics.

Keywords: Magnetostriction, harmonic fields, electrical steel sheet, applied stress, magnetic flux

DOI: 10.3233/JAE-172255

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. S1, pp. 33-38, 2017

Authors: Ripka, Pavel | Vyhnánek, Jan | Chirtsov, Andrey

Article Type: Research Article

Abstract: Magnetic sensors used for non-destructive testing, metal detection and other applications are subjected to large perpendicular field. In this paper we show that the existing models describing the response of anisotropic magnetoresistors (AMR) cannot be used for fields larger than the critical value, which is 350 μ T for the Honeywell HMC1001. This critical value is one order of magnitude lower than the anisotropy field and it is decreasing with increased value of the measured field. From our findings it is clear that AMR sensors cannot be safely used in applications in which fields above 250 μ …T can appear. Neither flipping, nor feedback compensation can compensate for this error. We show that this behaviour is caused by the fact that the single-domain state of the AMR is broken at the mentioned critical field. Compared to that, fluxgate sensors including microfluxgates are by principle immune against the crossfield. Unlike in AMR, crossfield sensitivity in fluxgate sensors is second-order effect, which can be kept under control by proper design. We show that even crossfield of 10 mT does not cause significant degradation of the sensor precision. Show more

Keywords: Magnetic sensors, crossfield sensitivity

DOI: 10.3233/JAE-172256

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. S1, pp. 39-47, 2017

Authors: Xie, Shejuan | Tian, Mingming | Chen, Hong-En | Zhao, Ying | Wu, Lei | Chen, Zhenmao | Uchimoto, Tetsuya | Takagi, Toshiyuki

Article Type: Research Article

Abstract: One of the major safety issues in nuclear power plants is pipe wall thinning where the pipe is mainly of magnetic material. Due to the large magnetic relative permeability of piping and the skin depth effect, the conventional PECT method is difficult for detecting the opposite side wall thinning. In this study, a pulsed eddy current testing (PECT) method under magnetic saturation was proposed and validated through numerical simulations and experiments. First, the mechanism of how magnetic saturation can increase the skin depth was studied through numerical simulation with help of COMSOL Multiphysics software. Second, the detection sensitivity of magnetic …field signal and voltage signal for wall thinning defect of specimens with various magnetic permeability was investigated through numerical simulation. Finally, the experiments of magnetic saturation PECT were conducted, and the feasibility and superiority of the proposed magnetic saturation PECT method were demonstrated. Show more

Keywords: Magnetic material, magnetic saturation PECT, numerical simulation, experiment, detection sensitivity

DOI: 10.3233/JAE-172257

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. S1, pp. 49-59, 2017

Authors: Shilyashki, Georgi | Pfützner, Helmut

Article Type: Research Article

Abstract: Recently, we presented a novel tangential induction sensor for measurements of local induction values in soft magnetic lamination of machine cores. In contrast to traditional tangential field-coil sensors, it exhibits a soft magnetic ribbon as a nucleus. Sensors with SiFe ribbon were effectively tested for transformer core surfaces, while showing poor reproducibility in the interior. Also tests with thin Fe-based amorphous ribbons proved to lack reproducibility, mechanical stress through core clamping causing magneto-elastic effects. An alternative would be Co-based amorphous ribbons of minimum magnetostriction, however, linked with low saturation magnetization. As an optimum solution, we present here nanocrystalline ribbons …of 20 μ m thickness, combining high permeability, high saturation magnetization and almost zero-magnetostriction. The tendency of saturation due to very high permeability is met by optimized shortening of the nucleus, the demagnetizing effect offering good performance in a wide range of induction. Assembling by a combined 3D/2D printing procedure promises a total sensor thickness of the order of 100 μ m. Prototypes were effectively tested in the interior of a 3-package transformer core. While earlier sensors were restricted to peak induction measurements, the nanocrystalline ones offer detection of the waveform of local inductions. For the first time, measurements are possible in completely non-destructive way. Show more

Keywords: Nanocrystalline ribbons, magnetic sensors, induction distribution, laminated machine cores, transformer cores

DOI: 10.3233/JAE-172258

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. S1, pp. 61-68, 2017

Authors: Zhao, Hanyu | Ferrara, Enzo | Paltanea, Veronica Manescu | Paltanea, Gheorghe | Gavrila, Horia | Fiorillo, Fausto

Article Type: Research Article

Abstract: Strip samples of widths ranging between 5 mm and 30 mm were cut from different types of non-oriented magnetic steel sheets by means of guillotine shear cutting and water-jet technology and characterized from DC to 400 Hz. The measured magnetization curves and energy losses and their dependence on the strip width, that is, on the proportion of damaged to pristine sample cross-section, have been analyzed and modeled. While confirming an expected lighter material deterioration engendered by water-jet cutting, the analysis of the results remarkably shows that the evolution of the normal magnetization curve and the quasi-static magnetic losses with the …width of the cut strip follows a hyperbolic law. This novel finding permits one to predict, using minimum pre-emptive information, the evolution of normal magnetization curve and hysteresis loss from indefinitely wide to narrow fully degraded strip. The highly strain-hardened region is, in this way, estimated to propagate from the strip edge by about 2.1 mm and 1.6 mm in the punched and water-jet cut samples, respectively. The dynamic loss behavior is assessed by analysis of the excess loss component, in accordance with the statistical theory of losses. A small to moderate increase of the dynamic loss (i.e. of the excess loss) with decreasing strip width is found, following to some extent the behavior of the quasi-static loss. Show more

Keywords: Magnetic losses, non-oriented steel sheets, strain-hardening

DOI: 10.3233/JAE-172259

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. S1, pp. 69-76, 2017

Authors: He, Manru | Tong, Zongfei | Chen, Hong-En | Xie, Shejuan | Chen, Zhenmao

Article Type: Research Article

Abstract: To ensure the safety of nuclear power plants, the evaluation of material degradation due to mechanical micro-damages is of great importance. In previous researches, Non-destructive Evaluation (NDE) methods based on electromagnetic material properties such as the Magnetic Barkhausen Noise (MBN) method, the Magnetic Incremental Permeability (MIP) method and the Magnetic Flux Leakage (MFL) method were studied to evaluate the plastic deformation in ferromagnetic material such as the Reduced-activation Ferritic/Martensitic (RAFM) steel, which is a candidate fusion reactor material of special material property. However, the residual stress and plastic deformation are indivisible in most practical cases, which make the conventional NDE …methods hard to be applied to a satisfactory precision. To develop a method for simultaneous evaluation of residual stress and plastic deformation in a structure of RAFM steel, a hybrid NDE method using the signals of MBN, MIP and MFL methods was proposed and experimentally validated in this paper. At first, an online integrated NDE system of these three magnetic NDE techniques was developed and was adopted to measure the NDE signals during loading process for RAFM steel test-pieces of different residual plastic strains. A strategy to get both the stress and strain information from groups of the measured NDE signals was then proposed and validated. It was demonstrated that the residual stress and plastic deformation can be properly evaluated based on some selected feature parameters of the measured magnetic NDE signals by using the proposed evaluation procedure based on the known NDE calibration information of the target material. Show more

Keywords: Magnetic NDE, simultaneous evaluation, plastic deformation, residual stress, integrated method

DOI: 10.3233/JAE-172260

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. S1, pp. 77-85, 2017