International Journal of Applied Electromagnetics and Mechanics - Volume 59, issue 4

Authors: Wu, Jianbo | Xia, Hui | Huang, Xiaoming | Wu, Tingjun | Li, Erlong | Kang, Yihua

Article Type: Research Article

Abstract: Defects are usually developed on the outside of heat exchanger tubes due to large friction between the support plate and the tube. In this paper, in order to improve the accuracy of the MFL (magnetic flux leakage) testing for heat exchanger tubes, the influence of support plate on MFL testing is investigated. Firstly, the influence of support plate on the magnetization status is theoretically analyzed by magnetic circuit analysis. Then, numerical simulations are conducted to investigate the magnetization intensity of the tube at different locations. Finally, MFL experiments for heat exchanger tubes are performed, in which a differential induction coil …array is proposed to eliminate the background signal caused by support plate. The testing results show that the MFL signal amplitude is increasing with the defect moving from the center of the support plate to the edge, which should be taken into consideration in the evaluation of heat exchanger tubes. Show more

Keywords: Heat exchanger tube, support plate, MFL (magnetic flux leakage) testing, magnetization intensity

DOI: 10.3233/JAE-171102

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 4, pp. 1349-1356, 2019

Authors: Su, Zhiyi | Rosell, Anders | Ye, Chaofeng | Udpa, Lalita | Udpa, Satish S. | Tamburrino, Antonello

Article Type: Research Article

Abstract: Eddy current methods are commonly used in the inspection of riveted multilayer structures. In a practical scenario, steel rivets may be magnetized to varying levels which can distort the magnetic field and pose a major challenge since the distortion can result in false positives and negatives. This paper presents an invariance transformation procedure that renders the signal insensitive to changes in magnetization while retaining the sensitivity to defect information. The approach is first implemented on simulated data, where the signals from magnetized steel rivets can be generated under controlled variation of relative permeability. The algorithm is then validated on experimental …data acquired using steel rivets with different residual magnetization levels. Show more

Keywords: Nondestructive evaluation, eddy current, magnetoresistance, invariance transformation

DOI: 10.3233/JAE-171037

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 4, pp. 1357-1364, 2019

Authors: Woloszyn, Miroslaw

Article Type: Research Article

Abstract: This paper presents a magnetometric system with scalar sensors mounted on two independent platforms, which is used to detect sunken shipwrecks. Increasing the distance between the sensors allows for more precise measurement of the difference in the magnetic induction module than in the case of sensors mounted e.g. on the aeroplane’s wings. This type of system makes it possible to enlarge detection range of the sunken wrecks.

Keywords: Magnetic field, magnetometer, localization

DOI: 10.3233/JAE-171231

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 4, pp. 1365-1375, 2019

Authors: Pávó, József | Gyimóthy, Szabolcs | Bálint, Botond | Bilicz, Sándor | Vértesy, Gábor | Tomáš, Ivan

Article Type: Research Article

Abstract: Magnetic flux simulations were utilized in a novel magnetic measurement method performed for the detection of local thinning of ferromagnetic plates. It was shown by numerical simulation, how parameters affect detectability of the defects. Linear relationship was found between the evaluated parameters and size of the artificial slot. Good correlation was found between theoretical and experimental results.

Keywords: Magnetic nondestructive testing, magnetic flux simulation, magnetic adaptive testing

DOI: 10.3233/JAE-171211

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 4, pp. 1377-1384, 2019

Authors: Jomdecha, Cherdpong | Cai, Wenlu | Xie, Shejuan | Li, Yong | Chen, Zhenmao

Article Type: Research Article

Abstract: The purpose of this study is to characterize the features of magnetic flux density perturbation as a result of the variation of conductivity in an equivalent model of the stress-corrosion crack (SCC). By using numerical computation of A-𝜙 method, the magnetic field nearby the inspection target was simulated for an eddy current probe of large rectangular excitation coil and a conductor plate with a modeled SCC. A conductive notch was set in the center of the conductor plate as an equivalent crack model of a real SCC. Different conductivities and crack depths were varied into the equivalent SCC model for …analyzing their influences to the distribution of magnetic flux density perturbation above the model plate. Numerical results showed that the distributions of magnetic flux density were suitable to distinguish the difference of the conductivities of the SCC between 0% and 20% of the base material for normal testing frequencies. In addition, it was also found that the profile of distributed conductivity along the crack length can be better represented with the field induced by the excitation current laterally to the crack length. Show more

Keywords: Magnetic flux distribution, stress corrosion crack, equivalent conductivity, eddy current testing

DOI: 10.3233/JAE-171140

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 4, pp. 1385-1392, 2019

Authors: Yoshioka, Saijiro | Kuboyama, Eiki | Gotoh, Yuji

Article Type: Research Article

Abstract: As for the alternating magnetic flux leakage testing of non-destructive inspection, the alternating magnetic field with high frequency is used. Therefore, this inspection method is not used for inspection of the opposite side defect in the steel plate. In this paper, the inspection method of the opposite side defect in the steel plate is proposed by this inspection method using the magnetizing current of the square wave on direct-current bias. This inspection principle is investigated by 3-D nonlinear FEM analysis taking account of magnetizing properties of minor loop and eddy current in the steel plate.

Keywords: Alternating magnetic flux leakage testing, AC square wave on DC bias magnetic field, 3-D nonlinear FEM, minor loop

DOI: 10.3233/JAE-171111

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 4, pp. 1393-1400, 2019

Authors: Wang, Cheng | Huang, Haiyang | Zhang, Tianshu | Chen, Yewang | Zhang, Yiwen | Cheng, Jianwei

Article Type: Research Article

Abstract: To address the problems of singularities, sensitivity to measurement noise, and low efficiency in traditional principal component analysis (PCA)-based operational modal analysis (OMA), we present a Sanger neural network principal component analysis (SNNPCA) algorithm to identify the operational modal parameters. SNNPCA is a two-layer neural network that is trained using a generalized Hebbian algorithm to ensure that its output converges to the principal components. After SNNPCA has converged, the link weights of SNNPCA correspond to the separation matrix of PCA. In SNNPCA-based OMA, the measurement response points are set as the input neurons, modal coordinate response signals are set as …the output neurons, and the link weights of the neural network represent the modal shapes. Therefore, the operational modal identification process in SNNPCA is physically meaningful and convergent. Furthermore, SNNPCA inherits the parallel nature of neural network algorithms, so it is also insensitive to measurement noise. Simulation results show that SNNPCA can identify the principal modal parameters accurately using only measurement response signals. This method can be applied in embedded devices to realize online monitoring and real-time fault diagnosis. Show more

Keywords: Operational modal analysis, principal component analysis, Sanger neural network, generalized Hebbian rule, parallel, measurement noise

DOI: 10.3233/JAE-171011

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 4, pp. 1401-1412, 2019

Authors: Xiang, Chunping | Qin, Qinghua | Yu, Xuehui | Chen, Shangjun | Zhang, Wei | Xia, Yuanming | Wang, Mingshi | Wang, T.J.

Article Type: Research Article

Abstract: Sandwich structures are widely used in engineering due to their superior mechanical properties. In the present paper, the failure modes of fully clamped sandwich beams with aluminum foam cores subjected to low-velocity impact on the mid-span were investigated experimentally and theoretically. Two dominant failure modes were observed through the drop-weight tests, which are core shear and indentation. Based on the experimental observations, a failure mechanism map was constructed theoretically by utilizing the quasi-static method. It is found that the quasi-static method is valid to predict the failure modes of the sandwich beams under impact.

Keywords: Sandwich beams, low-velocity impact, failure modes, failure mechanism map

DOI: 10.3233/JAE-171246

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 4, pp. 1413-1420, 2019

Authors: Nakagawa, Masayoshi | Yonemori, Hironobu

Article Type: Research Article

Abstract: This paper describes the effect of power supply noise on the acoustic noise and pan vibration when making use of the IH (Induction Heating) cooker. Recently, due to the spread of power electronics device, noise superimposed on the AC power supply is a problem. It has been reported that the acoustic noise provides discomfort feeling when using the IH cooker. Other studies have concluded that the vibration of a pan due to the induction heating is the noise source. In this paper, it is elucidated the influence on the pan’s vibration and the acoustic noise when the amplitude of the …noise superimposed on the power supply is changed and it is clarified the lowest power supply noise level, which is corresponding to the recognizable audible noise. Show more

Keywords: IH cooker, acoustic noise, pan’s vibration, power source noise

DOI: 10.3233/JAE-171236

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 4, pp. 1421-1430, 2019

Authors: Tian, Shuxia | Xiao, Yanqiu | Liu, Jianxiu | Fan, Jianglei | Xie, Guizhong | Du, Wenliao

Article Type: Research Article

Abstract: In this paper, a method based on structural vibration characteristic was proposed to detect the debonding defects of the lattice sandwich plate. At first, based on the finite element method, the vibration behavior of the sandwich plates were simulated for delamination damages of different locations and damage degree. Then, based on the Uniform Load Surface (ULS) curvature parameter, the debonding defects were identified by using the difference method. At last, the wavelet analysis method was applied to overcome the dependence on the unflawed model. The validity and efficiency of the proposed methods was demonstrated through numerical simulations and preliminary experiments.

Keywords: Lattice sandwich plate, delamination defect, modal shapes, ULS curvature, defect identification

DOI: 10.3233/JAE-171198

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 59, no. 4, pp. 1431-1439, 2019