International Journal of Applied Electromagnetics and Mechanics - Volume 55, issue 2

Authors: Du, Yali | Xie, Shejuan | Chen, Zhenmao | Zhu, Guangyi | Li, Peng

Article Type: Research Article

Abstract: With the growing interest to use composite materials in industrial fields such as the aerospace and the transportation engineering, more attention is devoted to the development and application of non-destructive testing (NDT) techniques to the inspection of defects in carbon fiber reinforced polymer (CFRP). High frequency eddy current testing method is considered to be a promising tool for the NDT of CRFP. In this work, an anisotropic numerical code based on Ar formulation is developed and validated at first. The detectability of four different types of ECT probes is then evaluated by using the developed numerical code for detecting the …crack type defects in CFRP laminates. Furthermore, the S/N ratios of the four probes related to the inclination noise are calculated numerically and compared to evaluate the detectability of these ECT probes. As conclusion, the newly proposed dual function vertical coil probe is found most suitable for the CFRP fiber breakage detection. Show more

Keywords: CFRP, anisotropic material, fiber breakage detection, Ar method

DOI: 10.3233/JAE-170083

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. 2, pp. 185-193, 2017

Authors: Chen, Feng | Wang, Jiawei | Bai, Xubin

Article Type: Research Article

Abstract: An Adaptive Discrete Geometric Approach is proposed for high-accuracy simulations of 2-D elliptic problems on the coarse grid. The idea is to reduce the error coming from the discretization of the constitutive equations by using the patch recovery technique. The integration-oriented scheme is adopted for the recovery procedure due to the high-precision of the regression functions. The accuracy and efficiency of the proposed approach are verified by the numerical tests.

Keywords: Discrete Geometric Approach, patch recovery, bicubic spline interpolation, constitutive matrix

DOI: 10.3233/JAE-170082

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. 2, pp. 195-203, 2017

Authors: Shangguan, YunQi | Yuan, JianSheng | Zou, Jun

Article Type: Research Article

Abstract: Induced magnetic field of ferromagnetic submarines will interfere with geomagnetic field in their surroundings, which makes possible localization of submarines through measuring the magnetic anomaly signals. This paper presents a localization method for submarines by measurements of the gradient tensor of the induced magnetic field at two positions. The components of the gradient tensor are measured approximately as a finite difference of two magnetometers of a detection array. Since the background field is eliminated in the difference, it can avoid the influence of either the time varying geomagnetic environment or other disturbance fields. The localization equations are based on the …independent components of the gradient tensor. By solving the equations, the submarine can be located accurately from a relatively far distance. The simulation shows that through this method and a detection array made by 7 single-axis magnetometers with a sensitivity of 10 pT, the maximum detection range can up to 500 m. Show more

Keywords: Submarine localization, geomagnetic field, detection array, two observation positions

DOI: 10.3233/JAE-170081

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. 2, pp. 205-212, 2017

Authors: Zhang, Chuang | Pang, Wenying | Liu, Suzhen | Li, Fubiao | Yang, Qingxin

Article Type: Research Article

Abstract: As one of the most common fatigue damage, the detection of the closed crack using regular ultrasonic technique always failed because of the contact state of its interface. Nonlinear ultrasonic method had been employed to improve the detecting precision. The electromagnetic acoustic method based on high pulse stimulation is studied in this paper. In order to get the accuracy information, a closed crack model based on the modified virtual spring function is proposed. The finite element (FE) model of the electromagnetic ultrasonic propagation in the aluminium plate with closed crack was developed, followed by a look at the simulation results …and analysis. An experimental setting which is coincident with the FE model is set up. By comparing of the simulation and experimental results, it is concluded that the tension and compression of the crack will cause the sound wave distortion and the ultrasonic nonlinear effect will be produced. The second harmonics is the typical feature of the nonlinearity. The propagation characteristic of surface wave in aluminium plate containing a closed crack is further analysed, which lays a foundation for the nonlinear detection of closed cracks. Show more

Keywords: Nonlinear ultrasound, closed crack, electromagnetic acoustic transducer, second harmonics

DOI: 10.3233/JAE-170080

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. 2, pp. 213-221, 2017

Authors: Kim, Sung-Jin | Park, Eui-Jong | Jung, Sang-Yong | Kim, Yong-Jae

Article Type: Research Article

Abstract: In this paper, the Box-Behnken design (BBD), which is a response surface method (RSM), was used to deduce a pole piece form that is able to effectively reduce the transfer torque ripple of a coaxial magnetic gear. A 2-D numerical analysis based non-linear finite element method (FEM) was used for the analysis between the response variables and the designed variables selected by the BBD. In addition, the reaction variable estimation equation based on the design variables was determined through a multiple regression analysis and analysis of variance (ANOVA). The characteristics of the initial model and optimum model deduced through a …response surface analysis were compared to prove the validity of the optimized design. Show more

Keywords: Coaxial magnetic gear, pole piece, transfer torque ripple, Box-Behnken design (BBD), response surface method (RSM), analysis of variance (ANOVA), finite element method (FEM), multiple linear regression analysis

DOI: 10.3233/JAE-170079

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. 2, pp. 223-234, 2017

Authors: Ma, Chao | Zhao, Yanzhen | Ma, Xikui

Article Type: Research Article

Abstract: In this paper, we propose several approaches to improve the efficiency of the optimization design for dry-type air-core reactors. Above all, by virtue of the empirical formula of the inductance of short solenoids, a neat formula for the inner diameter corresponding to the minimum mass of the reactor, termed optimal inner diameter, is presented, and a favorable range of the inner diameter is determined accordingly. Then, an efficient optimization model is established without frequently and repeatedly adjusting the design variables. In addition, genetic algorithm for the optimization design of the reactor is improved by introducing linear scaling and a dynamic …mutation operator. The proposed approaches are tested on the single-phase dry-type air-core reactor of 50 kVar with round conductors. An economic and qualified result can be obtained in a short period of time after the application of the approaches. The merits of these approaches could be more obvious for the large-capacity reactors. Show more

Keywords: Optimization model, dry-type air-core reactor, genetic algorithm

DOI: 10.3233/JAE-170067

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. 2, pp. 235-242, 2017

Authors: Yuan, Hongwei | Li, Xudong | Wang, Kaiqiang | Pei, Cuixiang | Chen, Zhenmao | Pan, Yudong

Article Type: Research Article

Abstract: In this work, a numerical method using a direct coupling algorithm is proposed for electromagneto-thermo-mechanical (EMTM) coupling analysis of structures in strong magnetic and thermal field. Both the electromagneto-mechanical (EMM) coupling effect and thermal effect are considered in the structural dynamical analysis. To realize this algorithm, a direct coupling element including degrees of freedom of displacement, temperature and electromagnetic fields is developed on the platform of the ANSYS user programmable features and verified by the comparison between the experimental data and simulation results of a typical EMTM problem. Finally, the EMTM dynamic response of a simplified model of the HL-2M …vacuum vessel during plasma vertical disruption events is simulated. According to the simulation results, the EMTM coupling effect is found significant and necessary to be considered for the design and safety evaluation of Tokamak structures. Show more

Keywords: Direct coupling algorithm, electromagneto-thermo-mechanical coupling effect, thermal effect, numerical simulation, Tokamak device

DOI: 10.3233/JAE-170067

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. 2, pp. 243-255, 2017

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

Article Type: Research Article

Abstract: This paper presents numerical simulation results of eddy current signals to determine the appropriated dimensions of imitative stress-corrosion cracks (SCCs) in viewpoint of similar eddy current testing signals. The imitative SCCs were modelled as multiple tiny slits in three dimensions. A Finite Element and Boundary Element hybrid method (FEM-BEM) was utilized to simulate the eddy current signals in an impedance form of an absolute pancake coil. Equivalent conductivity (σ E ) of the imitative SCCs was estimated by using a uniform notch model at a fixed width of 0.2 mm, and adjusting the conductivity in the notch …region. According to the numerical results, the impedance amplitude could be significantly used to quantify the σ E of imitative SCCs. In addition, the variation of test frequency affecting to σ E value was investigated. Finally, the appropriated imitative SCCs dimensions for the eddy current testing were quantitatively predicted by using a statistical methodology. Show more

Keywords: Stress corrosion cracks, imitative SCC, eddy current testing, FEM-BEM

DOI: 10.3233/JAE-170066

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. 2, pp. 257-269, 2017

Authors: Mo, Juan | Zhou, Chao | Yuan, Jiansheng

Article Type: Research Article

Abstract: Most of high voltage transmission lines use the stranded wire, while the surface of the shaped wire is smoother than the stranded one. It is investigated in this paper that how much the corona can be weakened by the shaped wire, by calculating the ion flow. The steady state corona model is employed, and a local domain surrounding the wire is chosen as the field domain to simulate the corona phenomena near the wire precisely. The equation system of corona model is a multi-physics coupled problem with electric field and particle diffusion and migration. The approach of defining and applying …the boundary conditions for negative and positive wires is proposed, and the solution of coupled problem is implemented by using software COMSOL. By the simulation of 500 kV transmission line, the corona current of the shaped wire is around 35% less than that of the stranded wire. Show more

Keywords: Corona loss, high voltage transmission line, shaped wire, stranded wire

DOI: 10.3233/JAE-170065

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. 2, pp. 271-278, 2017

Authors: Kiattisaksri, Peerapong | Phung-On, Isaratat | Poopat, Bovornchok

Article Type: Research Article

Abstract: This study presents an application of the swept-frequency eddy current (SFEC) technique for characterization of aging conditions of 5Cr-0.5Mo heat resistant steel by a U-shaped, eddy current probe. An optimal eddy current probe was established and employed to investigate the specimens under different simulated service conditions. Sweep frequencies from 500 to 10,000 Hz were generated to measure the impedance changes using a precision LCR meter. As results, the normalized impedances showed the highest differences in each aging condition at the frequency of 3,200 Hz. Microstructural observations were utilized to give details of the differences in microstructures among aged conditions, which …related to the carbide precipitation characteristics of the specimens. In addition, a micro-hardness was tested on the carbide colonies in complement the aged conditions. The results showed that the hardness correlated well to the normalized impedances obtained from the swept-frequency eddy current testing. Show more

Keywords: Eddy current, heat-resistant steel, swept-frequency, carbide precipitates

DOI: 10.3233/JAE-170064

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. 2, pp. 279-287, 2017