International Journal of Applied Electromagnetics and Mechanics - Volume 64, issue 1-4

Authors: Xia, Hui | Li, Erlong | Wu, Jianbo | Qiu, Qiao | Wang, Jie | Luo, Jiqing | He, Sha

Article Type: Research Article

Abstract: Pulsed eddy current thermography (PECT) and eddy current lock-in thermography (ECLIT) are non-destructive testing (NDT) techniques of high promising and interest in subsurface defect detection. In the previous researches, the induction coil was set above the defect region and it always parallel to the defect orientation. However, the location and orientation of subsurface defects cannot be determined before detection. Therefore, the scanning induction thermography (SIT) based on dynamic thermography is proposed by some researchers to localize and distinguish the subsurface defects. Still, the main challenges of SIT are how to detect the subsurface defect orientation and quantify the depth. So …that, the quantitative analysis in SIT with the new feature extraction methods was investigated and improved to detect the subsurface defect orientation and quantify the defect depth within 5 mm by using experimental studies. Show more

Keywords: Scanning induction thermography, max thermal response, fast Fourier transform, defect orientation detection, depth quantification

DOI: 10.3233/JAE-209400

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 64, no. 1-4, pp. 869-877, 2020

Authors: Alshits, V.I. | Lyubimov, V.N. | Nowacki, J.P. | Drabik, A.

Article Type: Research Article

Abstract: The new analytical theory is developed describing propagation of plasmon polariton localized at the interface between a dielectric uniaxial crystal and an isotropic metal. The theory relates to the crystal cut choice corresponding to the sagittal plane parallel to the optical axis. For this geometry the compact dispersion equation is derived admitting exact explicit solutions for all physical parameters of the plasmon polariton for an arbitrary slope of the optical axis to the interface plane. Results are illustrated for a series of uniaxial crystals with gold coatings.

Keywords: Polaritons, plasmons, electromagnetic waves, anisotropy, uniaxial crystals, isotropic metals

DOI: 10.3233/JAE-209401

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 64, no. 1-4, pp. 879-885, 2020

Authors: Liu, Chengyong | Li, Erlong | Wang, Shiqiang | Wu, Jianbo | Fang, Hui | He, Sha

Article Type: Research Article

Abstract: Magnetic Barkhausen Noise (MBN) detection technology shows great potential in the pipeline detection of stress, microstructure, and fatigue damage. However, in actual application, some pipes such as those near power plant are exposed to external magnetic fields or contain remanence. The presence of these magnetic fields will affect MBN features and then influence the testing results. To investigate the effect of DC magnetic field on MBN signal characteristics, theoretical analysis and experimental verification were carried out in this paper. It is found that the intensity and direction of the DC magnetic field have great effects on MBN signal characteristics, including …the changes in the energy of MBN signal, the peak position and the shape of MBN signal profile. Show more

Keywords: Magnetic Barkhausen noise, DC magnetic field, signal characteristics, pipeline

DOI: 10.3233/JAE-209402

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 64, no. 1-4, pp. 887-894, 2020

Authors: Yamaguchi, Toshihiko | Mihalache, Ovidiu

Article Type: Research Article

Abstract: The paper focus on a new combined experimental methodology and signal processing for an EMAT based on a Halbach magnet system in order to increase smaller defect detection in thick metallic plates. The visualization of the EMAT signal using a novel dynamic C-scan procedure is based on a continuous movement of the transducer above plate and an off-line signal processing that is enhanced and optimized for detection of small defects (5%) located on the opposite side of metallic plates (50 mm). The feasibility and performance of the acquisition signal method, and several signal processing algorithms are validated using experimental measurements. The …results present an optimized two-dimensional visualization technique for EMAT signal, which can be used for continuous surface scans of plates for detection of smaller defects that self-calibrate as the scan is conducted. Show more

Keywords: Nuclear reactor vessel, austenitic stainless steel, EMAT, Halbach magnet array, C-scan

DOI: 10.3233/JAE-209403

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 64, no. 1-4, pp. 895-903, 2020

Authors: Mihalache, Ovidiu | Yamaguchi, Toshihiko

Article Type: Research Article

Abstract: The paper presents a fast and accurate algorithm to reconstruct the magnetization model of parallelepiped magnet (parts of a Halbach magnet array) or the Halbach magnet array used in an electromagnetic acoustic (EMAT) transducer. The model accuracy is validated against measurements of the magnetic flux distributions above surface of block magnets or Halbach magnet array using 2D/3D theoretical formula to compute magnetic flux distribution, validated by 2D/3D FEM simulations, and based on a non-uniform distribution of reconstructed magnetization model (using only main magnetization component). The illness of inverse reconstruction model is controlled through very small enough increments steps in an …adaptive iterative algorithm but large enough increments to assure faster reconstruction, and converging to the same magnetization model of magnet blocks or Halbach array magnet, independent of the initial magnetization values. Show more

Keywords: EMAT, Halbach magnetization reconstruction, 3D finite element

DOI: 10.3233/JAE-209404

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 64, no. 1-4, pp. 905-912, 2020

Authors: Zhang, Xu | Cheng, Jiang | Qiu, Gongzhe | Tu, Jun | Song, XiaoChun | Cai, Chen

Article Type: Research Article

Abstract: The electromagnetic acoustic transducer (EMAT) is widely used in In-Line Inspection of gas pipeline. However, the transduction efficiency of the EMAT transmitter is lower compared with the traditional piezoelectric transducer and needs improving. To enhance the amplitude of the received signal, an improved periodic-permanent-magnet EMAT is provided as well as its construction method to generate shear horizontal guided waves propagating in the circumferential direction. By designing a racetrack coil and magnetic array with the same radian of the annular pipeline, the EMAT is more suitable to generate the circumferential wave in the pipeline. The performance of the EMAT transmitter has …been assessed with the validated finite element model. Show more

Keywords: EMAT, circumferential shear horizontal guided wave, finite element method

DOI: 10.3233/JAE-209405

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 64, no. 1-4, pp. 913-919, 2020

Authors: Deng, Zhiyang | Wei, Shilin | Chen, Tao | Song, Xiaochun | Kang, Yihua

Article Type: Research Article

Abstract: In the determination of metal thickness by traditional electromagnetic nondestructive testing methods, the material’s electrical conductivity and magnetic permeability are required but practically unavailable or inexact. In this paper, a wall-thinning measuring method based on magnetic permeability variation of steel pipes is proposed. The direct current magnetization is applied to the ferromagnetic material, the internal magnetic field perturbation caused by the wall-thinning brings the permeability perturbation in the surface layer and be sensed by eddy current probe. The simulation results show that the permeability perturbation is closely related to wall thickness loss. The experiment results show that the signal amplitude …increases with the thickness of the wall-thinning and the new method can measure the 10% wall-thinning of pipe. Finally, theoretical range of magnetization current values are discussed. The new method takes advantage of the changes in permeability and is not limited by thickness of object to be detected. Show more

Keywords: Wall-thinning, magnetic permeability perturbation, eddy current, magnetization

DOI: 10.3233/JAE-209406

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 64, no. 1-4, pp. 921-930, 2020

Authors: Chai, Wenping | Kwon, Byung-il

Article Type: Research Article

Abstract: The paper proposes a hybrid-excited wound field synchronous machine (HE-WFSM), which can achieve high reluctance torque utilization. The key of the proposed HE-WFSM is that two permanent magnets (PMs) assist each rotor pole in forming an additional magnetic flux circle. It is opposite to the magnetic flux circle along the q -axis in the WFSM. The reduction of the q -axis flux can help to improve the saliency ratio and reluctance torque. Additionally, the asymmetrical flux linkage achieves a closest current phase angle between the maximum field torque and the maximum reluctance torque. To highlight the advantages of the proposed …HE-WRSM, a general WFSM was adopted as the basic machine and analyzed under the same operating conditions. All performances of the basic machine and proposed HE-WFSM were predicted using finite element analysis (FEA) in Jmag-Designer. Finally, it was confirmed that the proposed HE-WRSM can achieve high reluctance torque utilization. Show more

Keywords: Hybrid-excited wound field synchronous machine, high reluctance torque utilization, finite element analysis

DOI: 10.3233/JAE-209407

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 64, no. 1-4, pp. 931-939, 2020

Authors: Lee, Sung-hyun | Baloch, Noman | Kwon, Byung-il

Article Type: Research Article

Abstract: This paper proposes a double consequent pole changing vernier machine (DCPCVM) which adopts double consequent pole and flux modulation configuration. The proposed machine combines a vernier machine and a permanent magnet synchronous machine (PMSM) in a single topology. Therefore, the advantages of both machines can be realized in a single topology. The proposed machine provides high torque at low speed while operating in vernier mode whereas it operates in PMSM mode at high speed to avoid the disadvantages of vernier machines at high speeds such as high core losses. Parametric analysis of the proposed machine is performed to show the …effect of the main variables on the electromagnetic characteristics of the machine. A finite element method (FEM) analysis is conducted, and meaningful conclusions are drawn. Show more

Keywords: DCPCVM, pole changing, vernier machine, PMSM, parametric analysis

DOI: 10.3233/JAE-209408

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 64, no. 1-4, pp. 941-949, 2020

Authors: Liu, Tianhao | Jin, Yu | Pei, Cuixiang | Han, Jie | Chen, Zhenmao

Article Type: Research Article

Abstract: Small-diameter tubes that are widely used in petroleum industries and power plants experience corrosion during long-term services. In this paper, a compact inserted guided-wave EMAT with a pulsed electromagnet is proposed for small-diameter tube inspection. The proposed transducer is noncontact, compact with high signal-to-noise ratio and unattractive to ferromagnetic tubes. The proposed EMAT is designed with coils-only configuration, which consists of a pulsed electromagnet and a meander pulser/receiver coil. Both the numerical simulation and experimental results validate its feasibility on generating and receiving L(0,2) mode guided wave. The parameters for driving the proposed EMAT are optimized by performance testing. Finally, …feasibility on quantification evaluation for corrosion defects was verified by experiments. Show more

Keywords: Guided wave, EMAT, pulsed electromagnet, tube inspection

DOI: 10.3233/JAE-209409

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 64, no. 1-4, pp. 951-958, 2020