International Journal of Applied Electromagnetics and Mechanics - Volume 42, issue 1

Authors: Li, Chao | He, Si-Yuan | Yang, Jiong | Zhang, Zhe | Xiao, Bo-Xun | Zhu, Guo-Qiang

Article Type: Research Article

Abstract: The electromagnetic scattering from two-dimensional two-layer dielectric random rough surfaces is analyzed in this work based on Monte Carlo (MC) simulations. The random rough surface is characterized with Gaussian statistics for surface correlation length and for surface root mean square (RMS) height. The Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHWT) surface integral equation is adopted and implemented. A rigorous three-dimensional (3-D) multilevel UV method combined with adaptive cross approximation (ACA) is proposed to solve for the unknown …electric and magnetic surface currents. By calculating monostaitc statistical radar cross section (RCS) of the layered structure, the influence of the rough surface RMS height, the correlation length, the medium permittivity and the layer thickness on the scattering characteristic is investigated. Show more

Keywords: Two-layer, rough surface, MLUV/ACA, BICGSTAB, PMCHW

DOI: 10.3233/JAE-121640

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 1, pp. 1-11, 2013

Authors: Li, Fen-Qiang | Fang, Yang | Zhu, Ying | Mo, Jian-Hua | Li, Jian-Jun

Article Type: Research Article

Abstract: In this paper, a 3D numerical simulation method was put forward by coupling magnetic-structural fields, and its reliability was verified through comparing with the experimental data offered by Suzuki. According to the characteristics of electromagnetic expansion of metal tube, this simulation method was used to analyze the uniformity of tube expansion when the length of tube was less than that of the coil. Meanwhile, a curve of homogeneity of electromagnetic tube expansion with different aspect ratios …(ratio of length to diameter) of tube was given based on the criterion of uniformity on deformation at the condition of specific parameters presented in this paper. By analyzing the mechanical characteristics of tube expansion, a length range of tube was found where the tube deformed uniformly. The results derived from this paper provided a good guidance for optimization design of electromagnetic ring expansion experiments which will be conducted on and this could ultimately promote the application of electromagnetic forming. Show more

Keywords: Electromagnetic tube expansion, 3D numerical simulation, evaluation criterion, homogeneity of deformation

DOI: 10.3233/JAE-121641

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 1, pp. 13-25, 2013

Authors: Jun, Jiang | Jingmeng, Liu | Weihai, Chen | Wenjie, Chen

Article Type: Research Article

Abstract: This paper presents the concept design of a novel uniaxial force sensor with two stage force resolutions. Unlike conventional stain-gauge-based force sensing devices, the developed force sensor measures an external force through measuring the displacement of a movable member suspended by a compliant mechanism. The compliant mechanism is specially designed to have two stiffness values within its workspace. The low stiffness is used for small range and fine resolution force measurement, while the high stiffness is …used for large range and coarse resolution force measurement. In order to get the required performance, the static stiffness as well as the dynamics of the sensing system is analyzed both analytically and numerically. After a prototype sensor is fabricated, preliminary characterization tests are carried out to verify the accuracy of the theoretical model and validate the effectiveness of the proposed design. The experimental results indicate that the structure of the force sensor is compact, and it has the ability to measure both micro range and macro range forces within one setup, meanwhile keeps very fine resolutions. Show more

Keywords: Force sensor, compliant mechanism, static stiffness, natural frequency

DOI: 10.3233/JAE-121642

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 1, pp. 27-39, 2013

Authors: Han, Yong | Zhao, Yongping | Ding, Mingli

Article Type: Research Article

Abstract: A new optimizing method of mathematical analytical modeling of induced current for electronic anti-fouling technology is used in the present study to solve the problem of large calculated amount and complex deducing process caused by traditional segmented function method under different excitation signal, and an exact 2D finite element method is used to calculate induced current in a real electronic anti-fouling system, and the finite element calculation results can fit well with the results calculated by …the optimizing analytical model of induced current under the excitation signal with different waveform. Furthermore, the average power density of induced current and the efficiency of energy transformation for EAF system are calculated to estimate the system performance under different excitation signal. The calculation result shows that: 1 the positive – negative square wave excitation signal can make the largest average power density of induced current and the sine wave excitation signal makes the smallest; 2 the sawtooth wave excitation signal can make the highest efficiency of energy transformation and the positive – negative square wave excitation signal makes the lowest. Show more

Keywords: Electronic anti-fouling (EAF) system, induced current, average power density, efficiency of energy transformation

DOI: 10.3233/JAE-121643

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 1, pp. 41-53, 2013

Authors: Zhou, Zhi-Dong | Fu, Zhi-Peng | Jiang, Quan

Article Type: Research Article

Abstract: A thin stiff film subjected a compressive force on a compliant substrate can form wrinkles. Buckling stiff piezoelectric thin films hold great applications for micro- and nano-electromechanical systems. The present study focuses on the buckling process of a piezoelectric thin film bonded to a compliant layer, which in turn lies on a rigid support. Nonlinear electromechanical equations for the buckling of a thin piezoelectric plate are employed to model the piezoelectric film poled in the thickness …direction. By solving the boundary value problem, the critical buckling condition and the wavelength of the buckles for substrates of various moduli and the thicknesses are obtained and discussed. The effect of piezoelectricity on the critical buckling condition of piezoelectric film is examined. It is found that the piezoelectricity has a stiffening effect, which is not negligible. Show more

Keywords: Buckling, piezoelectric thin films, nonlinear equations

DOI: 10.3233/JAE-121644

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 1, pp. 55-61, 2013

Authors: Valagiannopoulos, Constantinos A.

Article Type: Research Article

Abstract: A cloaking device comprised of a metallic cloaked region and a radially inhomogeneous cladding, obeying to a power law, is analyzed. Semi-analytical approximations are performed and simple formulas of the coating's optimal material profile are derived, based on the structure's miniature size. The variations of the coating's permittivities with respect to the operating frequency and the physical dimensions of the structure are shown and discussed.

Keywords: Cylindrical cloak, inhomogeneous coating, power-law

DOI: 10.3233/JAE-121645

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 1, pp. 63-71, 2013

Authors: He, Wei | Liu, Zehui | Hutchcraft, W. Elliott | Gordon, Richard K. | Zhang, Ruiqiang | Yang, Fan

Article Type: Research Article

Abstract: In this paper, an improved MLPG method has been introduced to simplify the algorithm and thus make it more suitable for dealing with engineering problems with complex domains. In the case of a complex domain with an irregular global boundary, it can be very hard to determine the intersections between the local sub-domains and the global boundary. The improvements of the MLPG method make the MLPG method only require the domain integrations. The intersections between local …sub-domains and the global boundary as well as boundary integrations have been avoided. A rectangular problem domain and a circular problem domain with exact solutions have been studied in this paper to investigate the accuracy of the improved MLPG method. The results show that compared to the regular MLPG method, the improved MLPG method can have the same accuracy, but the improved method is much easier to deal with irregular boundaries or complex problem domains. Show more

Keywords: Local Petrov-Galerkin method, meshless, electromagnetic problems

DOI: 10.3233/JAE-121646

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 1, pp. 73-83, 2013

Authors: Shi, Yan | Gao, Cun-Fa | Chang, Chao

Article Type: Research Article

Abstract: On the crack problem of ferromagnetic solids, almost all studies in previous literatures used two simple crack models, e.g., permeable and impermeable crack models. This means that a crack is always assumed to be a slit without thickness (mathematical crack). In fact, when a ferromagnetic solid with a crack is placed in magnetic fields, the mechanical/or magnetic loadings will make the crack opening and the high magnetic fields will be induced inside the deformed crack. Thus, …the crack should be modeled as a semi-permeable cavity. In the present work, the semi-permeable crack model is adopted to study the fracture problems of a soft ferromagnetic solid. The general solutions are derived for complex potential functions and the intensity factors of fields. For some special cases, more explicit solutions are given and compared with those in literature. Numerical results are also presented to discuss the effects of magnetic fields inside the crack on fracture behavior of the ferromagnetic solid, and it is found that the model of semi-permeable crack is more reasonable than that of permeable crack or impermeable crack. Show more

Keywords: Soft ferromagnetic solid, semi-permeable crack, singular fields

DOI: 10.3233/JAE-121647

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 1, pp. 85-97, 2013

Authors: Aw, Hong-Seng | Chiang, Chao-Wen | Tsai, Nan-Chyuan

Article Type: Research Article

Abstract: A TDOF (Two Degrees of Freedom) Servo Gap-Retained Mechanism (SGRM) is proposed and verified by experiments in this work. It mainly consists of a flywheel and an Intelligent Posture Tracking System (IPTS). The flywheel, driven by an induction motor for spinning, is regarded as the tracking objective of the IPTS. The IPTS is mainly composed by an intelligent disc and the Hybrid Magnetic Actuators (HMAs). The posture of the intelligent disc is controlled by the magnetic …forces induced by the HMAs to retain a constant gap with respect to the eccentric flywheel which spins, tilts and wobbles. Since the HMA is highly nonlinear, a Feedback-Linearized Sliding Mode Control (FLSMC) is synthesized to account for system parameter nonlinearities or unmodeled dynamics. The dynamics of the flywheel and the IPTS are theoretically investigated and analyzed. In fact, the proposed SGRM is a part of an entire flywheel cell. That is, once the MGU (Motor/Generator Unit) in flywheel cell operates at idle mode, the shaft of flywheel will be separated apart from MGU in order to avoid the energy loss of the flywheel by the back EMF induced by the magnetic field of MGU. On the other hand, the shaft of flywheel and MGU still need to maintain synchronous power transmission even at idle mode so that a non-contact clutch is equipped. Generally speaking, the role of SGRM in a flywheel cell is to ensure the centerline of the flywheel properly aligned with the non-contact clutch. At last, intensive computer and experimental simulations are undertaken to verify the feasibility of the proposed SGRM and FLSMC. It is evidently showed that the proposed SGRM under FLSMC exhibits superior transient response and servo capability upon constant gap retained. The steady-state tracking errors are about 5% with respect to the amplitudes of the reference trajectories in two radial directions (i.e., X-axis and Y-axis). Show more

Keywords: Servo gap-retained mechanism, hybrid magnetic actuator, feedback-linearized sliding mode control

DOI: 10.3233/JAE-131649

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 1, pp. 99-117, 2013

Authors: Flórez, Guillermo A. Díaz | Mombello, Enrique Esteban

Article Type: Research Article

Abstract: This paper proposes a fast and accurate methodology to calculate the magnetic field produced by a finite disk considering a linear variation of the current density between the inner and the outer radius. The mathematical expressions have been developed with the aim of reducing the computational effort, while ensuring accurate and reliable results. Additionally, the strategies presented in this work provide expressions which are free of singularities.

Keywords: Finite disk, Biot-Savart law, quadrature, magnetic field

DOI: 10.3233/JAE-131650

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 1, pp. 119-136, 2013

Authors: Chang, Lin | Lian, Jie

Article Type: Research Article

Abstract: The magneto-optical Kerr effect (MOKE) of ultrathin film grown on non-magnetic anisotropic substrate has been investigated. The formula of Longitude Magneto Optical Kerr effect for this structure is derived to find out the influence of the anisotropic substrate on the magneto optical properties of the sample. The change of Kerr rotation as a function of the incident angle is also given, which can be used to find a proper angle in sample measurement. Finally, a numerical …simulation was carried out to find out the relation between Kerr rotation and optical properties of the anisotropic substrate which can be used to select suitable substrate on which the film grows. Show more

Keywords: Magneto optical, kerr effect, non-magnetic, uniaxial, substrate, matrix optic theory

DOI: 10.3233/JAE-131651

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 1, pp. 137-145, 2013

Authors: Tian, Hongyan | Wang, Xingzhe | Zhou, You-He

Article Type: Research Article

Abstract: This paper presents a solution to an inhomogeneous problem of electromagnetic wave propagation through a functionally graded wave-absorbing (FGWA) infinite thin plate. The FGWA plate compounded by dielectric and magnetic materials has an arbitrary inhomogeneity through its thickness. The characteristics of the electromagnetic wave absorption and the temperature field due to the heat energy arising from electromagnetic wave absorption in the plate are analyzed. The results demonstrate that the electromagnetic wave absorption …properties have been significantly improved for the gradient absorbing plate in comparison with the homogeneous one. With the proper gradient distribution design of material properties, the FGWA plate shows good performance on the lower reflection and high absorption. Show more

Keywords: Functionally graded wave-absorbing plate, absorption and reflection, power dissipation, thermal properties

DOI: 10.3233/JAE-131652

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 1, pp. 147-156, 2013