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Pei Jun Wei - One of the best experts on this subject based on the ideXlab platform.

  • dispersion relations of anti plane Elastic Waves in micro scale one dimensional piezoelectric semiconductor phononic crystals with the consideration of interface effect
    Mechanics of Materials, 2021
    Co-Authors: Xiao Guo, Pei Jun Wei, Man Lan
    Abstract:

    Abstract In this paper, the propagation properties of anti-plane Elastic Waves in a piezoelectric semiconductor (PS) layered periodic composites are theoretically investigated. The periodic layered composites consist of periodically repeated two micro-scale geometrical thickness PS slabs with different Elasticity, piezoelectricity and charge carriers. Following consideration of the coupling mechanical anti-plane displacement, electric potential and perturbation of charge carriers, the influences of interface effects resulted from homo- and hetero-junctions on the dispersion relations of anti-plane Elastic Waves are systematically discussed. It is found that homo- and hetero-junctions can be approximately treated as rigid imperfect interfaces, which can enhance the width of band-gaps of anti-plane Elastic Waves, especially for high-frequency short-wavelength anti-plane Elastic Waves. The establishment of mathematical models and the revelation of physical mechanisms are all fundamental to the analysis and optimization of micro-scale energy harvesters based on the propagation of anti-plane Elastic Waves.

  • dispersion relations of in plane Elastic Waves in nano scale one dimensional piezoelectric semiconductor piezoelectric dielectric phononic crystal with the consideration of interface effect
    Applied Mathematical Modelling, 2021
    Co-Authors: Xiao Guo, Pei Jun Wei
    Abstract:

    Abstract In this paper, the propagation properties of in-plane Elastic Waves in a nano-scale N-type piezoelectric semiconductor material/piezoelectric dielectric material layered periodic composite are theoretically investigated. Under the background of classical continuum mechanics of solids, the transfer matrix method and the Bloch theorem, the transfer matrices of the N-type piezoelectric semiconductor material, the piezoelectric dielectric material and the interface and the dispersion equation of in-plane Bloch Waves are derived mathematically. Basing on the numerical calculation results, we investigate the physical influences of the semiconductor effect, biasing electric fields and the interface effect on the dispersion curves of in-plane Elastic Waves. It is found that the electron carrier mobility and diffusion will reduce the equivalent rigidity of the N-type piezoelectric semiconductor material, which will be limited by the existence of biasing electric fields. On the basis of the propagation of in-plane Elastic Waves, both the mathematical model and the physical mechanisms are fundamental to the analysis and optimization of nano-scale energy harvesters.

  • dispersion relations of Elastic Waves in one dimensional piezoelectric piezomagnetic phononic crystal with initial stresses
    Ultrasonics, 2016
    Co-Authors: Xiao Guo, Pei Jun Wei
    Abstract:

    The dispersion relations of Elastic Waves in a one-dimensional phononic crystal formed by periodically repeating of a pre-stressed piezoelectric slab and a pre-stressed piezomagnetic slab are studied in this paper. The influences of initial stress on the dispersive relation are considered based on the incremental stress theory. First, the incremental stress theory of Elastic solid is extended to the magneto-electro-elasto solid. The governing equations, constitutive equations, and boundary conditions of the incremental stresses in a magneto-electro-elasto solid are derived with consideration of the existence of initial stresses. Then, the transfer matrices of a pre-stressed piezoelectric slab and a pre-stressed piezomagnetic slab are formulated, respectively. The total transfer matrix of a single cell in the phononic crystal is obtained by the multiplication of two transfer matrixes related with two adjacent slabs. Furthermore, the Bloch theorem is used to obtain the dispersive equations of in-plane and anti-plane Bloch Waves. The dispersive equations are solved numerically and the numerical results are shown graphically. The oblique propagation and the normal propagation situations are both considered. In the case of normal propagation of Elastic Waves, the analytical expressions of the dispersion equation are derived and compared with other literatures. The influences of initial stresses, including the normal initial stresses and shear initial stresses, on the dispersive relations are both discussed based on the numerical results.

  • Dispersion relations of Elastic Waves in one-dimensional piezoelectric phononic crystal with mechanically and dielectrically imperfect interfaces
    Mechanics of Materials, 2016
    Co-Authors: Xiao Guo, Pei Jun Wei
    Abstract:

    The effects of mechanically and dielectrically imperfect interfaces on dispersion relations of Elastic Waves in a one-dimensional piezoelectric phononic crystal are studied in this paper. Six kinds of imperfect interfaces between two different piezoelectric materials constituting the phononic crystal are considered. These imperfect interfaces include: the mechanically compliant dielectrically weakly conducting interface, the mechanically compliant dielectrically highly conducting interface, the grounded metallized interface, the low dielectric interface, the tangent fixed interface and the tangent slippery interface. Based on transfer matrices of piezoelectric slabs and imperfect interfaces, the total transfer matrix of a typical single cell in the periodical structure is obtained. Furthermore, the Bloch theorem is used to obtain the dispersive equations of in-plane and anti-plane Bloch Waves. The dispersive equations are solved numerically and the numerical results are shown graphically. In the case of normal propagation of Elastic Waves within piezoelectric slabs, the analytical expressions of the dispersion equations are derived and compared with other literatures. The influences of mechanically and dielectrically imperfect interfaces on the dispersive relations are discussed based on the numerical results. (C) 2015 Elsevier Ltd. All rights reserved.

  • reflection of micropolar Elastic Waves at the non free surface of a micropolar Elastic half space
    Acta Mechanica, 2015
    Co-Authors: Peng Zhang, Pei Jun Wei, Qiheng Tang
    Abstract:

    The reflection problem of the micropolar Elastic Waves at the non-free surface of a micropolar Elastic half-space is studied in this paper. Different from the classic Elastic solid, there are four kinds of Elastic Waves in the micropolar Elastic solid and three of them are dispersive. The boundary conditions at the non-free surface of a micropolar Elastic half-space are used to obtain the linear algebraic equation sets from which the amplitude ratios of reflection Waves to the incident wave can be determined. Then, the reflection coefficients in terms of energy flux ratios are calculated numerically, and the normal energy flux conservation is used to validate the numerical results. At last, the influence of the boundary parameters, which reflect the mechanical behavior of the non-free surface, on the reflection energy partition of micropolar Elastic Waves is discussed based on the numerical results. Two cases of incident longitudinal displacement wave and incident coupled transverse displacement and transverse microrotational wave are considered.

Sylvain Ballandras - One of the best experts on this subject based on the ideXlab platform.

  • theoretical analysis of damping effects of guided Elastic Waves at solid fluid interfaces
    Journal of Applied Physics, 2006
    Co-Authors: Sylvain Ballandras, Vincent Laude, A Khelif, M Wilm, A Reinhardt, W Daniau, Virginie Blondeaupatissier
    Abstract:

    A theoretical description of ideal and viscous fluid media is proposed to address the problem of modeling damping effects of surface acoustic Waves and more generally of any guided Elastic Waves at the interface between viscous fluids and solids. It is based on the Fahmy-Adler eigenvalue representation of the Elastic propagation problem, adapted to provide Green’s function of the considered media. It takes advantage of previous efforts developed to numerically stabilize Green’s-function computation process. This function is used to compute a harmonic admittance according to the Blotekjaer approach. The influence of acoustic radiation and viscosity effects on different kinds of Waves excited on various substrates is reported and discussed.

  • guided Elastic Waves along a rod defect of a two dimensional phononic crystal
    Physical Review E, 2004
    Co-Authors: A Khelif, Vincent Laude, M Wilm, Sylvain Ballandras, B Djafarirouhani
    Abstract:

    It was shown that Elastic Waves propagating out-of-plane in a two-dimensional phononic crystal can experience full-band-gaps for nonzero values of the wave-vector component parallel to the rods. By further inserting a rod defect, it is demonstrated that modes propagating along the rod defect can be localized within the band-gaps of the phononic crystal. Such waveguide modes are exhibited for a tungsten/epoxy composite containing an aluminum nitride rod as the rod defect. It is expected that guided modes of such a structure can

  • Guided Elastic Waves along a rod-defect of a two-dimensional phononic crystal
    Physical Review E : Statistical Nonlinear and Soft Matter Physics, 2004
    Co-Authors: A Khelif, Vincent Laude, M Wilm, Sylvain Ballandras
    Abstract:

    It was shown that Elastic Waves propagating out-of-plane in a two-dimensional phononic crystal can experience full-band-gaps for nonzero values of the wave-vector component parallel to the rods. By further inserting a rod defect, it is demonstrated that modes propagating along the rod defect can be localized within the band-gaps of the phononic crystal. Such waveguide modes are exhibited for a tungsten/epoxy composite containing an aluminum nitride rod as the rod defect. It is expected that guided modes of such a structure can be excited and detected electrically owing to the piezoelectric effect.

  • out of plane propagation of Elastic Waves in two dimensional phononic band gap materials
    Physical Review E, 2003
    Co-Authors: M Wilm, A Khelif, Vincent Laude, Sylvain Ballandras, B Djafarirouhani
    Abstract:

    We have used a plane-wave-expansion model to study the out-of-plane propagation of Elastic Waves in a two-dimensional phononic band-gap material. The case of quartz rods embedded in an epoxy matrix has been computed. Band gaps for nonzero values of the wave-vector component parallel to the rods are shown to exist and are investigated. For wavelengths smaller than the period of the structure, modes are found that are localized in the epoxy intersites, and propagate perpendicularly to the plane of the structure.

A Khelif - One of the best experts on this subject based on the ideXlab platform.

  • theoretical analysis of damping effects of guided Elastic Waves at solid fluid interfaces
    Journal of Applied Physics, 2006
    Co-Authors: Sylvain Ballandras, Vincent Laude, A Khelif, M Wilm, A Reinhardt, W Daniau, Virginie Blondeaupatissier
    Abstract:

    A theoretical description of ideal and viscous fluid media is proposed to address the problem of modeling damping effects of surface acoustic Waves and more generally of any guided Elastic Waves at the interface between viscous fluids and solids. It is based on the Fahmy-Adler eigenvalue representation of the Elastic propagation problem, adapted to provide Green’s function of the considered media. It takes advantage of previous efforts developed to numerically stabilize Green’s-function computation process. This function is used to compute a harmonic admittance according to the Blotekjaer approach. The influence of acoustic radiation and viscosity effects on different kinds of Waves excited on various substrates is reported and discussed.

  • guided Elastic Waves along a rod defect of a two dimensional phononic crystal
    Physical Review E, 2004
    Co-Authors: A Khelif, Vincent Laude, M Wilm, Sylvain Ballandras, B Djafarirouhani
    Abstract:

    It was shown that Elastic Waves propagating out-of-plane in a two-dimensional phononic crystal can experience full-band-gaps for nonzero values of the wave-vector component parallel to the rods. By further inserting a rod defect, it is demonstrated that modes propagating along the rod defect can be localized within the band-gaps of the phononic crystal. Such waveguide modes are exhibited for a tungsten/epoxy composite containing an aluminum nitride rod as the rod defect. It is expected that guided modes of such a structure can

  • Guided Elastic Waves along a rod-defect of a two-dimensional phononic crystal
    Physical Review E : Statistical Nonlinear and Soft Matter Physics, 2004
    Co-Authors: A Khelif, Vincent Laude, M Wilm, Sylvain Ballandras
    Abstract:

    It was shown that Elastic Waves propagating out-of-plane in a two-dimensional phononic crystal can experience full-band-gaps for nonzero values of the wave-vector component parallel to the rods. By further inserting a rod defect, it is demonstrated that modes propagating along the rod defect can be localized within the band-gaps of the phononic crystal. Such waveguide modes are exhibited for a tungsten/epoxy composite containing an aluminum nitride rod as the rod defect. It is expected that guided modes of such a structure can be excited and detected electrically owing to the piezoelectric effect.

  • out of plane propagation of Elastic Waves in two dimensional phononic band gap materials
    Physical Review E, 2003
    Co-Authors: M Wilm, A Khelif, Vincent Laude, Sylvain Ballandras, B Djafarirouhani
    Abstract:

    We have used a plane-wave-expansion model to study the out-of-plane propagation of Elastic Waves in a two-dimensional phononic band-gap material. The case of quartz rods embedded in an epoxy matrix has been computed. Band gaps for nonzero values of the wave-vector component parallel to the rods are shown to exist and are investigated. For wavelengths smaller than the period of the structure, modes are found that are localized in the epoxy intersites, and propagate perpendicularly to the plane of the structure.

William J Parnell - One of the best experts on this subject based on the ideXlab platform.

  • employing pre stress to generate finite cloaks for antiplane Elastic Waves
    Applied Physics Letters, 2012
    Co-Authors: William J Parnell, Andrew N Norris, Tom Shearer
    Abstract:

    It is shown that nonlinear Elastic pre-stress of neo-Hookean hyperElastic materials can be used as a mechanism to generate finite cloaks and thus render objects near-invisible to incoming antiplane Elastic Waves. This approach appears to negate the requirement for special cloaking metamaterials with inhomogeneous and anisotropic material properties in this case. These properties are induced naturally by virtue of the pre-stress. This appears to provide a mechanism for broadband cloaking since dispersive effects due to metamaterial microstructure will not arise.

  • nonlinear pre stress for cloaking from antiplane Elastic Waves
    arXiv: Classical Physics, 2012
    Co-Authors: William J Parnell
    Abstract:

    A theory is presented showing that cloaking of objects from antiplane Elastic Waves can be achieved by Elastic pre-stress of a neo-Hookean nonlinear Elastic material. This approach would appear to eliminate the requirement of metamaterials with inhomogeneous anisotropic shear moduli and density. Waves in the pre-stressed medium are bent around the cloaked region by inducing inhomogeneous stress fields via pre-stress. The equation governing antiplane Waves in the pre-stressed medium is equivalent to the antiplane equation in an unstressed medium with inhomogeneous and anisotropic shear modulus and isotropic scalar mass density. Note however that these properties are induced naturally by the pre-stress. Since the magnitude of pre-stress can be altered at will, this enables objects of varying size and shape to be cloaked by placing them inside the fluid-filled deformed cavity region.

  • nonlinear pre stress for cloaking from antiplane Elastic Waves
    Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2012
    Co-Authors: William J Parnell
    Abstract:

    A theory is presented showing that cloaking of objects from antiplane Elastic Waves can be achieved by employing nonlinear Elastic pre-stress in a neo-Hookean elastomeric material. This approach would appear to eliminate the requirement of metamaterials with inhomogeneous anisotropic shear moduli and density. Waves in the pre-stressed medium are bent around the cloaked (cavity) region by inducing inhomogeneous stress fields via pre-stress. The equation governing antiplane Waves in the pre-stressed medium is equivalent to the antiplane equation in an unstressed medium with inhomogeneous and anisotropic shear modulus and isotropic scalar mass density. Note however that these properties are induced naturally by the pre-stress. As the magnitude of pre-stress can be altered at will, this enables objects of varying size and shape to be cloaked by placing them inside the fluid-filled deformed cavity region.

Jinkyu Yang - One of the best experts on this subject based on the ideXlab platform.

  • bloch oscillation of Elastic Waves in the graded lattice of 3d printed hollow elliptical cylinders
    Applied Physics Letters, 2019
    Co-Authors: Hyunryung Kim, Xiaotian Shi, Eunho Kim, Jinkyu Yang
    Abstract:

    We study the Bloch oscillation of Elastic Waves in a chain composed of hollow elliptical cylinders (HECs). These HECs are 3D-printed in different wall thicknesses and are arranged to form a graded chain. We find that the frequency band structure of this lattice can be manipulated in a way to create a narrow strip of transmission range sandwiched between slanted stop bands. This results in the trapping of Elastic Waves at a specific location of the chain, which depends on the input frequency of the propagating Elastic Waves. This Elastic Bloch oscillation in a tailorable 3D-printed system enables the control of energy localization in solids, potentially leading to engineering applications for vibration filtering, energy harvesting, and structural health monitoring.

  • bloch oscillation of Elastic Waves in the graded lattice of 3d printed hollow elliptical cylinders
    arXiv: Applied Physics, 2018
    Co-Authors: Hyunryung Kim, Xiaotian Shi, Eunho Kim, Jinkyu Yang
    Abstract:

    We study the Bloch oscillation of Elastic Waves in a chain composed of hollow elliptical cylinders (HECs). These HECs are 3D-printed in different wall thicknesses and are arranged to form a graded chain. We find that the frequency band structure of this lattice can be manipulated in a way to create a narrow strip of transmission range sandwiched between slanted stop bands. This enables the trapping of Elastic Waves at a specific location of the chain, which depends on the input frequency of the propagating Elastic Waves. This Elastic Bloch oscillation in a tailorable 3D-printed system enables the control of energy localization in solids, potentially leading to engineering applications for vibration filtering, energy harvesting, and structural health monitoring.