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

  • Analysis of a mode-I Crack Perpendicular to an imperfect interface
    International Journal of Solids and Structures, 2009
    Co-Authors: Xian Ci Zhong, Kang Yong Lee
    Abstract:

    The elastostatic problem of a mode-I Crack embedded in a bimaterial with an imperfect interface is investigated. The Crack is in proximity to and Perpendicular to the imperfect interface, which is governed by linear spring-like relations. The Fourier transform is applied to reduce the associated mixed-boundary value problem to a singular integral equation with Cauchy kernel. By numerically solving the resulting equation, stress intensity factors near both Crack tips are evaluated. Obtained results reveal that the stress intensity factors in the presence of the imperfect interface vary between that with a perfect interface and that with a completely debonding interface. Moreover, an increase in the interface parameters decreases the stress intensity factors. In particular, when Crack approaches to the weakened interface closer, the stress intensity factors become larger for a sliding interface, and become larger or smaller for a Winkler interface, depending on the Crack lying in a stiffer or softer material. The influences of the imperfection of the interface on the stress intensity factors for a bimaterial composed of aluminum and steel are presented graphically.

  • Dynamic stress intensity factor of a Crack Perpendicular to the weak-discontinuous interface in a nonhomogeneous coating-substrate structure
    Archive of Applied Mechanics, 2008
    Co-Authors: Kang Yong Lee, Nan Zhang
    Abstract:

    A mechanical model was established for the antiplane dynamic fracture problem of a functionally graded coating–substrate structure with a coating Crack Perpendicular to the weak-discontinuous interface. The problem was reduced to a Cauchy singular integral equation by the methods of Laplace and Fourier integral transforms. Erdogan’s collocation method and the Laplace numerical inversion proposed by Miller and Guy were used to calculate the dynamic stress intensity factors. Three conclusions were drawn through parametric studies: (a) unlike the conclusion drawn for an interfacial Crack, reducing the weak discontinuity of the interface will not necessarily decrease the dynamic stress intensity factor (DSIF) of the coating Crack Perpendicular to the interface; (b) increasing the stiffness of the substrate when that of the coating is fixed, or decreasing the stiffness of coating when that of the substrate is fixed, will be beneficial for the reduction of the DSIF of a coating Crack Perpendicular to the interface; and (c) the free surface has a greater influence on the DSIF than the interface does, and the effect of the interface on the DSIF is greater than that of the material stiffness in the Crack-tip region.

  • Dynamic stress intensity factors of two collinear mode-III Cracks Perpendicular to and on the two sides of a bi-FGM weak-discontinuous interface
    European Journal of Mechanics - A Solids, 2008
    Co-Authors: Kang Yong Lee, Yao Dai
    Abstract:

    The mechanical model was established for the anti-plane dynamic fracture problem for two collinear Cracks on the two sides of and Perpendicular to a weak-discontinuous interface between two materials with smoothly graded elastic properties, as opposed to a sharp interface with discontinuously changing elastic properties. The problem was reduced as a system of Cauchy singular integral equations of the first kind by Laplace and Fourier integral transforms. The integral equations were solved by Erdogan's collocation method and the dynamic stress intensity factors in the time domain were obtained through Laplace numerical inversion proposed by Miller and Guy. The influences of geometrical and physical parameters on the dynamic stress intensity factors were illustrated and discussed, based on which some conclusions were drawn: (a) to increase the thickness of the FGM strip on either side of the interface will be beneficial to reducing the DSIF of a Crack Perpendicular to a bi-FGM interface and embedded at the center of one of the FGM strips; (b) To increase the rigidity of the FGM strip where the Crack is located will increase the DSIF. However, when the material in one side of the interface is more rigid, the DSIF of the interface-Perpendicular embedded Crack in the other side will be reduced; (c) To decrease the weak-discontinuity of a bi-FGM interface will not necessarily reduce the stress intensity factor of a Crack Perpendicular to it, which is different from the case of interfacial Crack; (d) For two collinear Cracks with equal half-length, when the distance between the two inner tips is less than about three times of the half-length, the interaction of them is intensified, however, when the distance is greater than this the interaction becomes weak.

  • Mechanical modeling and fracture analysis for a non-homogeneous weldment with a Crack Perpendicular to the interface
    International Journal of Solids and Structures, 2008
    Co-Authors: Hong-cai Zhang, Wei Tan, Kang Yong Lee
    Abstract:

    AbstractA new mechanical model is established for a non-homogeneous weldment with HAZs and fusion zones treated as functionally graded materials. The interface-Perpendicular anti-plane fracture problems are analyzed for the HAZ and the weld metal, respectively, by the methods of Fourier integral transform and Cauchy singular integral equation. Lobatto–Chebyshev collocation method put forth by Erdogan and Gupta is employed to obtain numerical results of stress intensity factor (SIF). Parametric studies yield three conclusions: (1) overmatching is more beneficial than undermatching to the reduction of the SIF of a HAZ Crack, however, the latter is more effective than the former in reducing the SIF of a weld-metal Crack; (2) the optimum value of mismatch factor is 1.0, and values too greater or too smaller than this should be avoided in engineering design; (3) when the mismatch factor is unequal to 1.0, the SIF could be reduced by increasing the absolute value of the non-homogeneity parameters of HAZs

  • an anti plane Crack Perpendicular to the weak micro discontinuous interface in a bi fgm structure with exponential and linear non homogeneities
    International Journal of Fracture, 2007
    Co-Authors: Kang Yong Lee
    Abstract:

    Treated was an anti-plane Crack Perpendicular to the interface of an exponential-type FGM strip bonded to another linear-type FGM substrate with infinite thickness. Through Fourier integral transform, the problem was reduced as a Cauchy singular integral equation, which was further solved numerically by the Lobatto–Chebyshev collocation method. Based on the numerical solution, the effects of the geometrical and physical parameters on the stress intensity factor (SIF) were analyzed and the following conclusions were obtained: (a) A notable discrepancy between the interface-Perpendicular Crack and the interfacial one is that, to reduce the weak-discontinuity of interface or to make the interface micro-discontinuous will not necessarily decrease the SIF of the former, but will surely decrease that of the latter. (b) When a Crack tip is situated very near to the interface (or free surface), its SIF will be high and totally dominated by the interface (or free surface). (c) To increase the stiffness of the FGM on one side of the interface is beneficial to preventing the Crack on the other side from growing toward the interface. Besides, some practical suggestions were further given for material design in the field of composites.

Baolin Wang - One of the best experts on this subject based on the ideXlab platform.

  • thermal shock resistance analysis of a semi infinite ceramic foam
    International Journal of Engineering Science, 2013
    Co-Authors: Yang X Zhang, Baolin Wang
    Abstract:

    Abstract This paper considers the fracture mechanics of a ceramic foam under sudden thermal load. The ceramic foam is of semi-infinite and contains an edge Crack Perpendicular to its surface. The temperature field and transient thermal stress field in un-Cracked medium are calculated first. Then, the stresses are used as the Crack surface traction with opposite sign to formulate the mixed boundary value problem. Numerical results for the stress and stress intensity factor are calculated as the functions of the thermal shock time, the Crack length and the relative density of the foam. Crack propagation behavior and the thermal shock resistance of the ceramic foam are discussed in details.

  • A piezoelectric material strip with a Crack Perpendicular to its boundary surfaces
    International Journal of Solids and Structures, 2002
    Co-Authors: Baolin Wang, Yiu-wing Mai
    Abstract:

    A Cracked piezoelectric material strip under combining mechanical and electrical loads is considered. The Crack is vertical to the top and bottom edges of the strip. The edges of the strip are parallel to the x-axis and Perpendicular to the z-axis. When a piezoelectric ceramic is poled, it exhibits transversely isotropic behavior. Among many possible poled axis orientations, a particular orientation when the poling direction lies parallel to x-axis is examined in this paper. Both impermeable Crack and permeable Crack assumptions are considered. Numerical results are included for three kinds of fracture mechanics specimens, namely an edge-Cracked strip, a double edge-Cracked strip, and a center-Cracked strip, subjected to uniform tensions and uniform electric displacement loads simultaneously, at the far ends. In addition, an edge-Cracked strip under pure bending and uniform electric displacement loads at the far ends is also investigated in this paper.

Fazil Erdogan - One of the best experts on this subject based on the ideXlab platform.

  • Fracture mechanics of orthotropic laminated plates—II. The plane strain Crack problem for two bonded orthotropic layers
    International Journal of Solids and Structures, 1993
    Co-Authors: Binghua Wu, Fazil Erdogan
    Abstract:

    Abstract In this paper the plane strain problem for two bonded orthotropic layers containing a Crack Perpendicular to the laminate surfaces is considered. After deriving the integral equation for the general problem, the solution is obtained for three main Crack geometries, namely an embedded Crack, a surface Crack and a Crack terminating at the interface under a remotely applied membrane load or bending moment. For the Crack terminating at the interface the necessary asymptotic analysis is carried out, the characteristic equation to determine the power of stress singularity β is obtained, and the influence of the material parameters on β is examined. The main results given in the paper consist of the stress intensity factors obtained for various Crack geometries, material combinations and loading conditions.

  • fracture mechanics of orthotropic laminated plates ii the plane strain Crack problem for two bonded orthotropic layers
    International Journal of Solids and Structures, 1993
    Co-Authors: Fazil Erdogan
    Abstract:

    Abstract In this paper the plane strain problem for two bonded orthotropic layers containing a Crack Perpendicular to the laminate surfaces is considered. After deriving the integral equation for the general problem, the solution is obtained for three main Crack geometries, namely an embedded Crack, a surface Crack and a Crack terminating at the interface under a remotely applied membrane load or bending moment. For the Crack terminating at the interface the necessary asymptotic analysis is carried out, the characteristic equation to determine the power of stress singularity β is obtained, and the influence of the material parameters on β is examined. The main results given in the paper consist of the stress intensity factors obtained for various Crack geometries, material combinations and loading conditions.

S. Ueda - One of the best experts on this subject based on the ideXlab platform.

  • transient thermal response of a functionally graded piezoelectric laminate with a Crack normal to the bimaterial interface
    Journal of Thermal Stresses, 2018
    Co-Authors: S. Ueda, Masayuki Okada, Yoshihisa Nakaue
    Abstract:

    In this article, the problem of a functionally graded piezoelectric material strip (FGPM strip) containing a Crack Perpendicular to the interface between the FGPM strip and a homogeneous layer is analyzed under transient thermal loading condition. The Crack faces are supposed to be completely insulated. Material properties are assumed to be exponentially dependent on the distance from the interface. Using the Laplace and Fourier transforms, the thermoelectromechanical problem is reduced to a singular integral equation, which is solved numerically. The stress intensity factors of embedded and edge Cracks are computed. The results for the Crack contact problem are also included.

  • Transient thermal response of a functionally graded piezoelectric laminate with a Crack normal to the bimaterial interface
    2017
    Co-Authors: Yoshihisa Nakaue, S. Ueda
    Abstract:

    In this paper, the fracture problem of a functionally graded piezoelectric material strip (FGPM strip) containing a Crack Perpendicular to the interface between an FGPM strip and a homogeneous layer is considered. The problem is solved for the laminate that is suddenly heated from the surface of the FGPM strip.  The surface of the homogeneous layer is maintained at the initial temperature. The Crack faces are supposed to be completely insulated. Material properties are assumed to be exponentially dependent on the distance from the interface. By using the Laplace and Fourier transforms, the thermo-electro-mechanical fracture problem is reduced to a singular integral equation, which is solved numerically. The stress intensity factors are computed and presented as a function of the normalized time, the nonhomogeneous and geometric parameters.

  • The surface Crack Problem for a Piezoelectric Slab with Functionally Graded Properties
    Transactions of the Japan Society of Mechanical Engineers. A, 2004
    Co-Authors: S. Ueda, Atsushi Hatagaki, Yuichiro Kanada
    Abstract:

    In this study the plane electroelasticity problem for a functionally graded piezoelectric slab containing a Crack Perpendicular to the boundaries is considered. It is assumed that the electroelastic properties of the medium vary continuously in the thickness direction. The problem is solved under a fixed grip and a uniform electric field conditions applied to the slab away from the Crack region. The stress intensity factors and the energy density factors are presented for embedded as well as edge Crack for various values of dimensionless parameters representing the size and the location of the Crack and the material nonhomogeneity.

  • Normal impact of a piezoelectric strip with an off-center Crack Perpendicular to interface
    Theoretical and Applied Fracture Mechanics, 2003
    Co-Authors: S. Ueda
    Abstract:

    Abstract The normal impact of a piezoelectric strip containing an off-center Crack Perpendicular to the boundaries is considered. The solution involves solving a singular integral equation in the Laplace transform domain by application of the Gauss–Jacobi integration formula. Laplace inversion is carried out numerically to obtain the dynamic energy density factors. They are greatly affected by the free boundaries of the piezoelectric strip and the material properties.

  • The Surface Crack Problem for a Layered Elastic Medium with a Functionally Graded Nonhomogeneous Interface
    JSME International Journal Series A, 2002
    Co-Authors: S. Ueda, Tatsuya Mukai
    Abstract:

    The plane elasticity solution is presented in this paper for the Crack problem of a layered medium. A functionally graded interfacial region is assumed to exist as a distinct nonhomogeneous transitional layer with the exponentially varying elastic property between the dissimilar homogeneous surface layer and the substrate. The surface layer contains a Crack Perpendicular to the surface. Fourier transforms are used to formulate the problem in terms of a singular integral equation. The main results presented are the variations of the stress intensity factors as functions of geometric and material parameters of the layered medium.

O P Sushko - One of the best experts on this subject based on the ideXlab platform.