J.-K. Du

Ningbo University, Ning-po, Zhejiang Sheng, China

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Publications (6)7.41 Total impact

  • J Zhang · Y P Shen · J K Du
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    ABSTRACT: The effect of inhomogeneous initial stress on Love wave propagation in layered magneto-electro-elastic structures is investigated in this paper. The coupled magneto-electro-elastic field equations are solved by adopting the Wentzel–Kramers–Brillouin (WKB) approximate approach. Then the phase velocity can be calculated by applying boundary and continuity conditions. A specific example of a structure consisting of a CoFe2O4 layer and a BaTiO3 substrate is used to illustrate the influence of inhomogeneous initial stress on the phase velocity, corresponding coupled magneto-electric factor and stress fields. The different influence between constant initial stress and inhomogeneous initial stress is discussed and the results are expected to be helpful for the preparation and application of Love wave sensors.
    No preview · Article · Feb 2008 · Smart Materials and Structures
  • J.-K. Du · D.-Y. Ye
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    ABSTRACT: Based on the linearly piezoelectric theory, SH wave propagation in laminated structure of functionally gradient piezoelectric material (FGPM) was analyzed by means of the transfer matrix method, and the effect of initial stress in the piezoelectric gradient coverage layer on SH wave propagation was investigated. The material properties of piezoelectric coverage layer present gradient change along the thickness, such as elasticity, piezoelectricity, dielectric coefficient and density. Numerical analysis results show that SH waves in the appropriate gradient distribution material would tend to propagate along the surface of the layer so as to obtain the better electromechanical coupling performance, and initial stress can cause a reduction of wave propagation velocity, but an increase of electromechanical coupling coefficient. The analysis methods and conclusions will provide a reference for ultrasonic inspection of solid rocket motor, and development and selection of piezoelectric sensors.
    No preview · Article · Jun 2005
  • J.K. Du · Y.P. Shen · D.Y. Ye · F.R. Yue
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    ABSTRACT: This paper presents an analysis of the scattering of anti-plane shear waves by a single piezoelectric cylindrical inhomogeneity partially bonded to an unbounded piezomagnetic matrix. The anti-plane governing equations for linearly magneto-electro-elastic medium are reduced to one Helmholtz and two Laplace's equations. The fields of scattered waves are obtained by means of the wave function expansion method on condition that the bonded interface is perfect. The region of the debonding is modeled as an interface crack with noncontacting faces. The magneto-electric permeable boundary conditions are adopted, i.e. the normal electric displacement, electric potential, normal magnetic induction and magnetic potential are continuous across the crack faces. The crack opening displacement is represented by Chebyshev polynomials and a system of equations is derived and solved for the unknown coefficients. Some examples are calculated and the results are figured. The results show that the COD increases as k1a becomes larger initially, then the COD decreases as k1a becomes larger still, where k1 is the incident wave number and a the inhomogeneity radius. The COD gets smaller as the piezoelectric coefficient of the inhomogeneity increases.
    No preview · Article · May 2004 · International Journal of Engineering Science
  • JK Du · YP Shen · WP Tian
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    ABSTRACT: This article presents an analysis of the scattering of anti-plane shear waves from a single cylindrical in homogeneity partially bonded to an unbounded magneto-electro-elastic matrix. The magneto-electric permeable boundary conditions are adopted. The crack opening displacement is represented by Chebyshev polynomials and a system of equations is derived and solved for the unknown coefficients. Some examples are calculated and the results are illustrated. The results show that the COD increases when the piezomagnetic coefficient of the inhomogeneity bonded to the piezoelectric matrix becomes larger, and that the COD decreases when the piezomagnetic coefficient of the matrix with the piezoelectric inhomogeneity increases.
    No preview · Article · Mar 2004 · Acta Mechanica Solida Sinica
  • J.-K. Du · F.-R. Yue · Y.-P. Shen · J.-X. He

    No preview · Article · Sep 2003
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    J. K. Du · YP Shen · X. Wang
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    ABSTRACT: This paper presents an analysis of the scattering of anti-plane shear waves by a single piezo-electric cylindrical inclusion partially bonded to an unbounded matrix. The anti-plane governing equations for piezoelectric materials are reduced to Helmholtz and Laplacian equations. The fields of scattered waves are obtained by means of the wave function expansion method when the bonded interface is perfect. When the interface is partially debonded, the region of the debonding is modeled as an interface crack with non-contacting faces. The electric permeable boundary conditions are adopted, i.e. the normal electric displacement and electric potential are continuous across the crack faces. The crack opening displacement is represented by Chebyshev polynomials and a system of equations is derived and solved for the unknown coefficients.
    Full-text · Article · Aug 2002 · Acta Mechanica