International Journal of Applied Electromagnetics and Mechanics - Volume Pre-press, issue Pre-press

Authors: Xie, Zheng | Shi, Pengpeng | Li, Qun | Chen, Zhenmao

Article Type: Research Article

Abstract: The influence of magnetic field on stress intensity factor at crack tips of a ferromagnetic material is studied in this paper. A method using a sequential coupling algorithm has been applied to solve this coupled problem explicitly. In order to realize the iterative calculation of the stress intensity factor, a semi-analytical solution of the magnetic field perturbation due to structural deformation near by the crack tips is derived at first. The Maxwell stress, the magnetostriction strain and the nonlinear mechanical property of the magnetic material are taken into consideration to cope with the magneto-mechanical coupling effects. Results of perturbed magnetic …field and distribution of magnetostriction strain at the crack tip are obtained and being evaluated quantitatively. Finally, the effects of the applied external magnetic field on stress intensity factor of a crack in a ferromagnetic material are discussed based on the numerical results. Show more

Keywords: Magnetoelastic, magnetostriction effect, stress intensity factor, ferromagnetic material

DOI: 10.3233/JAE-171156

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-11, 2018

Authors: Wang, Zhe | Cui, Ximing | Pu, Haiming | Kang, Yihua

Article Type: Research Article

Abstract: In order to illustrate influence of surface roughness on the energy change of excitation process in thickness measurement of electromagnetic acoustic transducer (EMAT), the change of Lorentz force during the excitation process is analyzed theoretically. A finite element simulation model of EMAT is established with different surface roughness. The distribution of eddy current density and Lorentz force density of different rough surface is discussed. The results show that the eddy current density gets nonuniform due to the irregular profile of the surface. The average value of Lorentz force density decreases with the increase of surface roughness Ra, which makes the …excitation energy of EMAT get weaker. Finally, the experiment results verify the analysis of the theory and finite element simulation. Show more

Keywords: Surface roughness, eddy current density, Lorentz force density, excitation energy change, EMAT

DOI: 10.3233/JAE-171121

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-8, 2018

Authors: Theodoulidis, Theodoros

Article Type: Research Article

Abstract: An exact method is presented for calculating the impedance of a coil above a planar conductor with a conductivity profile that varies with depth. The method can be applied to arbitrary continuous profiles and in terms of accuracy or scope it is advantageous over the existing approaches, namely the analytical approach involving the solution of the relevant differential equation in terms of higher transcendental functions and the numerical approach involving the piecewise approximation of the continuous conductivity profile. The method is also very fast and in the context of eddy current nondestructive evaluation it can be readily applied to invert …conductivity profiles from coil impedance measurements. Show more

Keywords: Eddy current testing, analytical modeling, continuous conductivity profile

DOI: 10.3233/JAE-171122

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-7, 2018

Authors: Ido, Yasushi | Iwamoto, Yuhiro | Li, Yan-Hom | Chen, Ching-Yao

Article Type: Research Article

Abstract: Behaviors of a magnetic microchain which is an oscillating motion of micrometer-size magnetic particles’ cluster caused by an external magnetic field were investigated numerically. The hybrid simulation code which was based on the lattice Boltzmann method, the immersed boundary method and the discrete particle method was developed. The behaviors of a magnetic microchain depends on the number of magnetic particles in the magnetic microchain, frequency of external alternating magnetic field and the strength of applied magnetic field. Three types of behaviors, i.e., rigid rotational oscillation, rotational oscillation with deforming into S shape and splitting into several chains, depends on the …number of magnetic particles. Show more

Keywords: Magnetic microchain, magnetic particle, alternating magnetic field, numerical simulation

DOI: 10.3233/JAE-171119

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-7, 2018

Authors: Endo, Ayato | Ikeda, Keigo | Mashino, Masahiro | Kato, Hideaki | Narita, Takayoshi | Moriyama, Hiroyuki

Article Type: Research Article

Abstract: Bioinstrumentation has been used in the automotive industry to evaluate the ride comfort level of different vehicles. However, there have been no studies attempting to incorporate bioinstrumentation in the controls. In this paper, we propose a ride comfort control system using the psychological state of the driver as estimated through bioinstrumentation. To evaluate the psychological state of the driver, we use the driver’s heart rate variability, which allows us to calculate the R-R interval and the LF/HF, the values of which reflect the activities of the autonomic nervous system. In this paper, we investigated the usefulness of a ride comfort …control system using adequate bioinstrumentation and switching criterions for the system. As the results indicate, the drivers become relaxed when using the ride comfort control system as based on their psychological state. Moreover, the drivers become more relaxed when using LF/HF as the switching criterion for ride comfort. Show more

Keywords: Ride comfort, autonomic nervous system activity, active seat suspension

DOI: 10.3233/JAE-171120

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-8, 2018

Authors: Sasayama, Teruyoshi | Enpuku, Keiji

Article Type: Research Article

Abstract: When testing ferromagnetic materials such as iron, low-frequency eddy-current testing (LF-ECT) is used to avoid the skin effect. However, the drawback of LF-ECT is that the signal becomes weak at low frequencies. Furthermore, when the specimen is covered with protective materials, the signal becomes even weak, owing to the large lift-off. To overcome these drawbacks, we utilize a high-temperature superconducting (HTS) coil and a pulse-width modulation (PWM) inverter in the LF-ECT method. Using an HTS coil and a PWM inverter, strong currents are conducted, and the change in the coil resistance can be easily measured. The small impedance change of …the HTS coil is detected by using a Maxwell bridge. The result demonstrates that a steel plate thickness of up to 20 mm can be estimated based upon the measurements of the change in the coil resistance, even when the lift-off is 98 mm. Show more

Keywords: High-temperature superconducting (HTS) coil, low-frequency eddy current testing, pulse width modulation (PWM) inverter

DOI: 10.3233/JAE-171117

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-8, 2018

Authors: Kamitani, Atsushi | Takayama, Teruou | Saitoh, Ayumu

Article Type: Research Article

Abstract: A high-performance method is developed for solving a linear system in the shielding current analysis of a high-temperature superconducting (HTS) film containing cracks. When the shielding current density is calculated in the HTS film, a linear system of special type has to be solved at each iteration cycle of the Newton method. If GMRES is applied to the solution of the linear system, its convergence property will be remarkably degraded with increasing crack size. In order to resolve this problem, other variables than corrections of the current vector potential are all eliminated from the linear system. Consequently, the residual history …of GMRES is hardly affected by a crack size so that its convergence property is improved remarkably. Show more

Keywords: Finite element method, high-temperature superconductor, linear-system solver, Newton method

DOI: 10.3233/JAE-171206

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-7, 2018

Authors: Ji, Hongli | Qiu, Jinhao | Wu, Yipeng | Zhang, Chao

Article Type: Research Article

Abstract: To overcome the drawbacks in the active and passive control systems, a low-powered semi-active approach based on synchronized switch damping techniques using piezoelectric materials have been developed. The synchronized switch damping (SSD) method, which consists in a nonlinear processing of the voltage on a piezoelectric actuator by switch control, is used to shift the phase and amplify the amplitude of the generated voltage on the piezoelectric element, which is helpful to enhance the energy conversion and control performance. In this paper, several new SSD control methods developed by the authors, including SSD control based on negative capacitance (SSDNC), and unsymmetrical …SSD, are introduced. Moreover, two examples of application of SSD methods in aerospace engineering are given. Finally, the future directions of research in semi-active control are also summarized. Show more

Keywords: Vibration control, semi-active, synchronized switch damping, piezoelectric element

DOI: 10.3233/JAE-171155

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-9, 2018

Authors: Mao, Boyong | Xie, Shilin | Zhang, Xinong

Article Type: Research Article

Abstract: Dielectric electro-active polymer (DEAP) is a new kind of smart material, which has a strong application potential in intelligent control field due to the large mechanical deformation under electrical stimulation. Based on the actuation performance of this material, the DC voltage is necessary for reciprocating actuation. Thus, it is essential to study the actuation performance under DC voltage. In this article, the actuation performance of a DEAP actuator under DC voltage is discussed, the electromechanical coupling model is firstly given considering the frequency-dependent characteristic of the dielectric elastomeric materials. Then the drive displacement performance under DC voltage is studied numerically …and experimentally. The simulation results are consistent well with the experimental ones and both demonstrate that this actuator have good displacement output capacity. Moreover, the influence of voltage on the dynamic stiffness of actuator and vibration isolation performance are investigated as well. The dynamic stiffness model of actuator is derived based on the electromechanical coupling model and the vibration isolation performances of a signal degree of freedom system under different DC voltages have been examined. The simulation and experiment results show that the DC voltage has little effect on the vibration isolation performance although the dynamic stiffness of actuator is related to voltage. Therefore, the dynamic characteristics of DEAP actuator can be regarded as to be invariable within a certain range of voltage. This feature of actuator are beneficial to vibration control application in the future. Show more

Keywords: Dielectric electro-active polymer, actuator, driving performance, isolation performance

DOI: 10.3233/JAE-171130

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-8, 2018

Authors: Zhang, Feng | Jiang, Changqing | Mo, Xiaolong | Liu, Yinghua | Xie, Huimin | Li, Luming

Article Type: Research Article

Abstract: Deep brain stimulation (DBS) is an effective therapy for treating neurological disorders, while magnetic resonance imaging (MRI) is a valuable method for clinical diagnosis and research. However, DBS systems in clinical MRI are under the influence of displacement force, torque and device vibration, which may be hazardous to patients after DBS implantation surgery. In this study, we evaluated these hazardous effects under 3T MRI. A set of apparatus were designed and built and the corresponding methods for safety assessment were also proposed. Results showed that the displacement force, torque and vibration of the DBS system under 3T MRI were safe. …Furthermore, this study demonstrates an example of an MRI compatibility test that can be applied to many other medical instruments. Show more

Keywords: Deep brain stimulation, magnetic resonance imaging, force, torque, vibration

DOI: 10.3233/JAE-171084

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-6, 2018