The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Kang Yong Lee - One of the best experts on this subject based on the ideXlab platform.

  • effect of an imperfect interface on the sh wave propagating in a cylindrical Piezoelectric Sensor
    Ultrasonics, 2010
    Co-Authors: Kang Yong Lee, Kang Yong Lee
    Abstract:

    Under harsh in situ conditions, the interface in Piezoelectric Sensors may be damaged mechanically and/or electrically. The damaged interface would in turn affect the electromechanical behaviors of the Sensors. The purpose of the present work is to study the effect of the imperfect interface on SH wave propagating in a cylindrical Piezoelectric Sensor. The dispersion relations of SH wave are derived analytically and the phase velocity are obtained numerically. Parametric studies on the phase velocity indicate that the mechanical imperfection may reduce the phase velocity under certain circumstances; however, the electrical imperfection has no obvious effect on the phase velocity in any cases; with the thickness of the Piezoelectric layer increasing, the phase velocity may increase, decrease or keep unchanged, depending on the combination of the values of the wave number and the mechanical imperfection parameter.

  • fracture analysis on the arc shaped interface in a layered cylindrical Piezoelectric Sensor polarized along its axis
    Engineering Fracture Mechanics, 2009
    Co-Authors: Kang Yong Lee, Kang Yong Lee
    Abstract:

    Fracture analysis is performed for the arc-shaped interface in a layered cylindrical Piezoelectric Sensor polarized along its axis. Parametric studies on the numerical results of the singular integral equation yield three guidelines for optimal designs of cylindrical Piezoelectric Sensors made for axial shear testing. (a) The optimal value of the radius ratio is from 1.1 to 1.5. (b) A stiff Piezoelectric layer plus a soft central cylindrical substrate can generate good strength matching on the interface. (c) An unelectroded rather than electroded outer surface is beneficial to reducing the stress intensity factor of the interface crack.

  • interaction between an electrically permeable crack and the imperfect interface in a functionally graded Piezoelectric Sensor
    International Journal of Engineering Science, 2009
    Co-Authors: Kang Yong Lee
    Abstract:

    For a cracked Piezoelectric Sensor with an imperfect interface, the interaction between the crack and the imperfect interface is a problem of practical significance. Such a problem is investigated by the method of singular integral equation in the present work. The interface is assumed to be mechanically compliant and weakly conducting. Parametric studies on stress intensity factors (SIFs) indicate that when the crack is near to the interface SIFs increase as the interface change from perfection to imperfection, and the mechanical imperfection generally has more remarkable influence on SIFs than the dielectric imperfection does. For a crack in the Piezoelectric layer and near to the interface, the SIF gets less sensitive to the variation of the substrate thickness if the interface becomes imperfect. The interfacial imperfection has less influence on the fracture behavior of a stiffer Piezoelectric layer.

  • Crack tip shielding and anti-shielding effects of the imperfect interface in a layered Piezoelectric Sensor
    International Journal of Solids and Structures, 2009
    Co-Authors: Kang Yong Lee
    Abstract:

    AbstractThe purpose of the present work is to study the effect of an imperfect interface on the fracture behavior of a layered Piezoelectric Sensor. For mathematical convenience, the problem is investigated under mode III-a simple case in fracture mechanics. Fracture analysis is performed by the methods of Fourier integral transform and Cauchy singular integral equation. Parametric studies on the numerical results of energy release rate reveal the crack tip shielding and anti-shielding effects of the imperfect interface. When the inclined angle of crack is less than 0.1π, the imperfect interface may shield the crack, however, when it is larger than 0.2π, the crack may be anti-shielded. If the distance between a crack tip and the imperfect interface is less than two times of the crack length, the shielding or anti-shielding effect is remarkable, and otherwise it is negligible. Finally, the crack tip shielding and anti-shielding effects of the mechanical imperfection are generally more remarkable than those of the dielectric imperfection

  • The shielding effect of the imperfect interface on a mode III permeable crack in a layered Piezoelectric Sensor
    Engineering Fracture Mechanics, 2009
    Co-Authors: Kang Yong Lee
    Abstract:

    The mechanical model is established for a Piezoelectric Sensor with a mode III permeable crack parallel to the imperfect interface. Fracture analysis is performed by the standard methods of Fourier transform and singular integral equation. Three conclusions are drawn: (a) the imperfect interface has a shielding effect on the crack parallel and very near to it; (b) the shielding effect depends on the structural stiffness and the distance between the crack and interface; (c) for the electrically permeable crack, mechanical imperfection has more remarkable shielding effect than dielectric imperfection does.

Sondipon Adhikari - One of the best experts on this subject based on the ideXlab platform.

  • Sensor shape design for Piezoelectric cantilever beams to harvest vibration energy
    Journal of Applied Physics, 2010
    Co-Authors: Michael I. Friswell, Sondipon Adhikari
    Abstract:

    Energy harvesting for the purpose of powering low power electronic Sensor systems has received explosive attention in the last few years. A common device uses the Piezoelectric effect for a cantilever beams at resonance to harvest ambient vibration energy. However most of these devices have a rectangular Piezoelectric patch covering all or part of the beam. This paper considers the optimum design of such a device, and in particular investigates the effect that the size and shape of Piezoelectric Sensor has on the harvested energy. It is shown that significant increases in harvested energy may be obtained by optimising the Sensor design.

Fangsen Cui - One of the best experts on this subject based on the ideXlab platform.

  • Hypervelocity impact induced shock acoustic emission waves for quantitative damage evaluation using in situ miniaturized Piezoelectric Sensor network
    Elsevier, 2019
    Co-Authors: Menglong Liu, Qiang Wang, Qingming Zhang, Renrong Long, Fangsen Cui
    Abstract:

    Manmade debris and natural meteoroids, travelling in the Low Earth Orbit at a speed of several kilometers per second, pose a severe safety concern to the spacecraft in service through the HyperVelocity Impact (HVI). To address this issue, an investigation of shock Acoustic Emission (AE) waves induced by HVI to a downscaled two-layer Whipple shielding structure is performed, to realize a quantitative damage evaluation. Firstly a hybrid numerical model integrating smooth-particle hydrodynamics and finite element is built to obtain the wave response. The projectiles, with various impact velocities and directions, are modelled to impact the shielding structure with different thicknesses. Then experimental validation is carried out with built-in miniaturized Piezoelectric Sensors to in situ sense the HVI-induced AE waves. A quantitative agreement is obtained between numerical and experimental results, demonstrating the correctness of the hybrid model and facilitating the explanation of obtained AE signals in experiment. Based on the understanding of HVI-induced wave components, assessment of the damage severity, i.e., whether the outer shielding layer is perforated or not, is performed using the energy ratio between the regions of “high frequency” and “low frequency” in the acquired AE signals. Lastly, the direct-arrival fundamental symmetric wave mode is isolated from each sensing signal to be input into an enhanced delay-and-sum algorithm, which visualizes HVI spots accurately and instantaneously with different Sensor network configuration. All these works demonstrate the potential of quantitative, in situ, and real time HVI monitoring using miniaturized Piezoelectric Sensor network. Keywords: Acoustic Emission (AE), Damage detection, Hypervelocity impact, Piezoelectric Sensor, Whipple shielding assembl

P. Martínez-aguilera - One of the best experts on this subject based on the ideXlab platform.

  • A cement-based Piezoelectric Sensor for civil engineering structure
    Materials and Structures Materiaux et Constructions, 2006
    Co-Authors: B Shen, M.j. Eneo (institution), I.e. Hernández-lópez, M.l. Zúñiga-vargas, Zili Li, Xu Yang, P. Martínez-aguilera
    Abstract:

    A new aggregate-like Sensor using Piezoelectric ceramic as sensing element was designed, fabricated and tested. The Sensor was made by bonding together two cuboids of hardened cement paste with a commercially available Piezoelectric ceramic plate in between, which is the sensing element. A new adhesive was developed during the fabrication of the Sensor. The Sensor was tested on its basic performance with a charge amplifier measuring system. First, the frequency response of the Sensor was investigated in the general frequency range of civil engineering structure, which is from 0.01 Hz to 40 Hz. Then the relationship between output and input of the Sensor was tested. Finally, complex, random and square loads were applied to observe the performance of the Sensors. The excellent compatibility with concrete and the good sensing performance enable the aggregate-like Sensor to be easily embedded into concrete structures like a real aggregate and to reliably monitor the vibration of host structure. There is a good potential for such a Sensor to be used in structural health monitoring.

Su Z - One of the best experts on this subject based on the ideXlab platform.

  • Hypervelocity impact induced shock acoustic emission waves for quantitative damage evaluation using in situ miniaturized Piezoelectric Sensor network
    'Elsevier BV', 2019
    Co-Authors: Liu M, Wang Q, Zhang Q, Long R, Cui F, Su Z
    Abstract:

    Manmade debris and natural meteoroids, travelling in the Low Earth Orbit at a speed of several kilometers per second, pose a severe safety concern to the spacecraft in service through the HyperVelocity Impact (HVI). To address this issue, an investigation of shock Acoustic Emission (AE) waves induced by HVI to a downscaled two-layer Whipple shielding structure is performed, to realize a quantitative damage evaluation. Firstly a hybrid numerical model integrating smooth-particle hydrodynamics and finite element is built to obtain the wave response. The projectiles, with various impact velocities and directions, are modelled to impact the shielding structure with different thicknesses. Then experimental validation is carried out with built-in miniaturized Piezoelectric Sensors to in situ sense the HVI-induced AE waves. A quantitative agreement is obtained between numerical and experimental results, demonstrating the correctness of the hybrid model and facilitating the explanation of obtained AE signals in experiment. Based on the understanding of HVI-induced wave components, assessment of the damage severity, i.e., whether the outer shielding layer is perforated or not, is performed using the energy ratio between the regions of “high frequency” and “low frequency” in the acquired AE signals. Lastly, the direct-arrival fundamental symmetric wave mode is isolated from each sensing signal to be input into an enhanced delay-and-sum algorithm, which visualizes HVI spots accurately and instantaneously with different Sensor network configuration. All these works demonstrate the potential of quantitative, in situ, and real time HVI monitoring using miniaturized Piezoelectric Sensor network.Department of Mechanical Engineering201906 bcma/bcwhpublished_fina