International Journal of Applied Electromagnetics and Mechanics - Volume 26, issue 1-2

Authors: Giordano, Stefano

Article Type: Research Article

Abstract: In this paper we analyse the electrical effects of the presence of cracks in solid conductors. We have studied such problematic from different points of view. Firstly, we have analytically evaluated the behaviour of the electrical field near a crack in an isotropic solid where a uniform current density is flowing, drawing a comparison with the behaviour of the well known stress and strain tensor fields in the analogue elastic problem. This computation has been made …with a slit-crack (two-dimensional field analysis) and with a circular crack (three-dimensional field analysis). So, in order to quantify the spatial fluctuations of the local electric field around the crack we have numerically found the density of states for the field showing that it exhibit sharp peaks and abrupt changes in the slope at certain critical points which are analogous to van Hove singularities in the density of states for phonons and electrons in solids. Finally, we have performed a theoretical analysis of the conductivity of a microcracked solid. The distribution of cracks in the solid follows a given orientational distribution, which modify the conduction properties of the overall material. In particular, we have shown that the conductivity depends exponentially on the cracks density and on the size of each crack embedded in the medium. Show more

Keywords: Electric cracks, field intensity factors, density of states, order parameters

DOI: 10.3233/JAE-2007-815

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 26, no. 1-2, pp. 1-19, 2007

Authors: Zhou, Zhi-Dong | Nishioka, Toshihisa | Kuang, Zhen-Bang

Article Type: Research Article

Abstract: A generalized screw dislocation in the piezoelectric trimaterial with two parallel plane interfaces is studied. The Burgers vector of the generalized screw dislocation normal to the isotropic base plane and a discontinuous electric potential locates in the isotropic plane, simultaneously a line force and a line charge are acted at the core. The singular solution of a generalized screw dislocation in a homogeneous piezoelectric ceramic is used as the basis for solving the piezoelectric trimaterial body. …A Schwarz-Neumann's alternating technique [1] is applied to construct this trimaterial solution. Further, the generalized Peach Koehler forces acting on the generalized screw dislocation are considered. Numerical illustrations for the interaction are given and some discussions on the effects of the material mismatches are given. It is shown that the present solutions are available and useful. Show more

Keywords: Piezoelectric composite, dislocation, trimaterial body, alternating technique, complex potential

DOI: 10.3233/JAE-2007-816

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 26, no. 1-2, pp. 21-36, 2007

Authors: Sha, Xu | Xianlong, Jin | Feng, Pang | Jie, Shen

Article Type: Research Article

Abstract: In this paper, the three-dimensional finite element model of a low voltage and heavy current three-phase busbar bridge system is established. The edge element is used to discretize the finite element equations of the electromagnetic field. The main characteristics of magnetic flux density and electromagnetic force in the system are obtained. Through the comparison between calculation results and measured ones, the reliability of the calculation is validated. The influence of the operating current, different …arrangements of three-phase busbars, space between each phase busbar and frequency on electro-magnetic parameters, especially magnetic flux density and electromagnetic force, are also studied. Show more

Keywords: Low voltage, heavy current, three-phase busbar bridge, eddy current field, edge element

DOI: 10.3233/JAE-2007-897

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 26, no. 1-2, pp. 37-49, 2007

Authors: Xu, Lizhong | Cai, Yi

Article Type: Research Article

Abstract: In this paper, based on electromagnetic theory and geometrics, the electromagnetic field of the worm coils for the drive is researched. A coordinate system is established and equations of the toroidal helical slots for three phase coils on worm are presented. By means of equation for magnetic vector at any point near coil, magnetic vector near single phase toroidal worm coils is introduced. Hence, the total magnetic vector near three phase toroidal worm coils is obtained …as well. Simulation results show: near toroidal worm, as a static current is applied to its one toroidal coil, a toroidal electromagnetic field is formed; when the 3-phase source is connected to the coils of the worm, a toroidal circular rotating electromagnetic field will drive several planets rotate about their own axial. And by means of magnetic forces between teeth of the planet and stator or worm, the rotor will be driven to rotate about its own axial and an output of low speed and large torque can be obtained. Show more

Keywords: Toroidal drive, electromechanical integrated, worm, electromagnetic field

DOI: 10.3233/JAE-2007-898

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 26, no. 1-2, pp. 51-67, 2007

Authors: Zhao, She-Xu | Lee, Kang Yong

Article Type: Research Article

Abstract: Within the framework of linear magnetoelasticity, the plane strain problem of a layered medium composed of three dissimilar soft ferromagnetic materials with a Yoffe-type moving crack at the interface is considered. The medium is subjected to a uniform in-plane magnetic field and the crack is opened by internal normal and shearing tractions. By using the Fourier integral transform technique, the current mixed boundary problem is reduced to a pair of integral equations of the second kind …with Cauchy-type singularities. To determine the dynamic magnetoelastic stress intensity factors, the singular integral equations are solved numerically by means of the Jacobi polynomial expansion method. Results are presented graphically to show the dependence of the DSIFs on the velocity of the moving crack, the magnetic field, the magnetic properties of the materials and the geometric parameter of the problem. Show more

Keywords: Layered soft ferromagnetic medium, moving interfacial crack, dynamic magnetoelastic stress intensity factors

DOI: 10.3233/JAE-2007-899

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 26, no. 1-2, pp. 69-85, 2007

Authors: Wang, B.L. | Han, J.C.

Article Type: Research Article

Abstract: In this paper, we developed a closed-form solution for a crack in a piezoelectric strip of finite width, subjected to in-plane mechanical and electrical loads. Explicit expressions for the stresses and the electric fields, together with their intensity factors are obtained for the two extreme cases of impermeable crack and permeable crack. Solutions for some special cases, such as a center crack, an edge crack, a semi-infinite medium, an infinite medium, two symmetric and collinear cracks, …and a row of collinear cracks, are also obtained. All solutions are given in closed-form. Show more

Keywords: Piezoelectric materials, fracture mechanics, cracks, exact solution

DOI: 10.3233/JAE-2007-900

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 26, no. 1-2, pp. 87-99, 2007

Authors: Hamid, A.-K. | Hussein, M.I.

Article Type: Research Article

Abstract: Exact solution to the electromagnetic radiation from a conducting slotted circular or elliptical cylinder coated by an Isorefractive metamaterials is derived by using the separation of variables technique. The fields inside and outside the dielectric layer are expressed in terms of Mathieu functions. No matrix inversion is required after obtaining expressions for the radiated field expansion coefficients by imposing the appropriate boundary conditions. Numerical results are plotted for the radiation pattern, aperture …conductance and antenna gain. The results show that slotted antenna coated with Isorefractive metamaterials has more directive beam and lower side-lobes compared to that coated with conventional dielectric or metamaterials. Show more

DOI: 10.3233/JAE-2007-901

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 26, no. 1-2, pp. 101-111, 2007

Authors: Lin, Chun-Bo | Chen, Shin-Cheng | Lin, Hsien-Mou

Article Type: Research Article

Abstract: An analytical solution for the magnetoelastic problem of an infinite soft ferromagnetic material with a hole of arbitrary shape is provided in this paper. Using the method of complex variable, such as conformal mapping technique and the analytic continuation, both the magnetic fields and magnetoelastic stresses can be obtained. Explicit solutions of several examples are also provided. Comparison with the degenerate case, such as a crack of which the analytic solutions were provided in the literature, …is made to assure that the solution of the present work is general and exact. Numerical results for the tangential magnetoelastic stresses on the surface of an elliptic hole or a hypotrochoidal hole are displayed in graphic form to elucidate the effect of geometry parameters. Moreover, the stress intensity factors with r^{-1/2} singularity on the crack tip are also derived. Show more

DOI: 10.3233/JAE-2007-902

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 26, no. 1-2, pp. 113-131, 2007

Authors: Nagaya, Kosuke | Notoya, Masayuki | Sakamoto, Naoya | Fujinaka, Tetsuya | Hata, Hideki | Zheng, J.

Article Type: Research Article

Abstract: A new spring type actuator is presented in which controls are possible by using usual control methods such as PID control. The actuator consists of a normal helical coil spring and a number of iron (ferrite) particles layers inside. The iron particles layers are made of silicon based adhesive material involving iron particles. The layers are pasted to the coil spring with a certain air gap between each layer. To achieve both extensive and compressive motions, …a permanent magnet is attached to the top of the spring and electromagnet to the base, and the motion of the top of the actuator is controlled by electric currents in the coil of the electromagnet. A method of forming the actuator is presented, and its design formulae are presented. The present actuator works well under the control. Especially, the size is small in comparison with such as moving coil actuators and the work area is large enough. Show more

Keywords: Spring, actuator, electromagnet, control, iron particles layer

DOI: 10.3233/JAE-2007-903

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 26, no. 1-2, pp. 133-146, 2007

Authors: Arunachalam, Kavitha | Udpa, Satish S. | Udpa, Lalita

Article Type: Research Article

Abstract: Several microwave tomography techniques have been developed to reconstruct the spatial distribution of the electrical property of penetrable objects. These techniques rely on solving the ill-posed nonlinear inverse scattering problem using field measurements acquired from multiple views at multiple frequencies and incorporate prior information during inversion to obtain a stable solution. Such techniques often employ a linear or circular antenna array with individual elements operating as a transceiver to acquire multiple field …measurements for imaging. In this paper a tomographic inversion technique with single fixed transmitter and a deformable mirror is proposed as an alternative to the conventional tomography system. Limitations arising from the use of a single transmitter for acquiring multi-view data for the ill-posed problem are overcome by using a continuously deformable mirror with reflective coating. The continuously deformable mirror controlled by an underlying actuator circuit steers the incident field towards the scatterer for multi-view field measurements. A theoretical analysis of the proposed microwave tomography technique including system design, theory, operating principles and selection of optimal mirror shapes to obtain information rich field measurements are discussed in this paper. Computational feasibility of the proposed inverse scattering technique is investigated for two-dimensional penetrable dielectric scatterer in the presence of measurement noise. Show more

Keywords: Deformable mirror, inverse scattering, tomography, microwaves

DOI: 10.3233/JAE-2007-904

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 26, no. 1-2, pp. 147-161, 2007