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1.
The anti-plane shear problem of bonded elastic materials containing a crack at an arbitrary angle to the graded interfacial
zone is investigated in this paper. The interfacial zone is modeled as a nonhomogeneous interlayer of finite thickness with
the continuously varying shear modulus between the two dissimilar, homogeneous half-planes. Formulation of the crack problem
is based upon the use of the Fourier integral transform method and the coordinate transformations of basic field variables.
The resulting Cauchy-type singular integral equation is solved numerically to provide the values of modeIII stress intensity factors. A comprehensive parametric study is then presented of the influence of crack obliquity on the stress
intensity factors for different crack size and locations and for different material combinations, in conjunction with the
material nonhomogeneity within the graded interfacial zone. 相似文献
2.
In this paper, we examine the singular stresses and electric fields in a functionally graded piezoelectric ceramic strip containing
an eccentric crack off the center line under anti-plane shear loading with the theory of linear piezoelectricity. It is assumed
that the properties of the functionally graded piezoelectric ceramic strip vary continuously along the thickness. Fourier
transforms are used to reduce the problem to the solution of two pairs of dual integral equations, which are then expressed
to a Fredholm integral equation of the second kind. Numerical values on the stress intensity factor and the energy release
rate are obtained. 相似文献
3.
The dynamic response of a cracked functionally graded piezoelectric material (FGPM) under transient anti-plane shear mechanical
and in-plane electrical loads is investigated in the present paper. It is assumed that the electroelastic material properties
of the FGPM vary smoothly in the form of an exponential function along the thickness of the strip. The analysis is conducted
on the basis of the unified (or natural) crack boundary condition which is related to the ellipsoidal crack parameters. By
using the Laplace and Fourier transforms, the problem is reduced to the solutions of Fredholm integral equations of the second
kind. Numerical results for the stress intensity factor and crack sliding displacement are presented to show the influences
of the elliptic crack parameters, the electric field, FGPM gradation, crack length, and electromechanical coupling coefficient. 相似文献
4.
Hyung Jip Choi 《Journal of Mechanical Science and Technology》1997,11(3):239-248
The mode I interaction of a periodic array of parallel cracks which are uniformly spaced apart in a functionally graded material
is investigated. The two-dimensional theory of nonhomogeneous elasticity is employed as the basic framework for this study.
The material nonhomogeneity is represented in terms of the spatial variation of the shear modulus in the exponential form
along the direction of cracks, while Poisson’s ratio is assumed to be constant. Formulation of the proposed mixed boundary
value problem is reduced to solving a hypersingular integral equation with the crack surface displacement as a new unknown
function. As a result, the variations of stress intensity factors are illustrated as a function of possible range of periodic
crack spacing in conjunction with the different values of the material nonhomogeneity parameter. Furthermore, crack opening
displaccements are presented for various geometric and material combinations. 相似文献
5.
The dynamic response of an eccentric Griffith crack in functionally graded piezoelectric ceramic strip under anti-plane shear
impact loading is analysed using integral transform method. Laplace transform and Fourier transform are used to reduce the
problem to two pairs of dual integral equations, which are then expressed to Fredholm integral equations of the second kind.
We assume that the properties of the functionally graded piezoelectric material vary continuously along the thickness. The
impermeable crack boundary condition is adopted. Numerical values on the dynamic stress intensity factors are presented for
the functionally graded piezoelectric material to show the dependence of the gradient of material properties and electric
loadings. 相似文献
6.
Hyung Jip Choi 《Journal of Mechanical Science and Technology》1994,8(1):52-62
The problem of an interlaminar crack in dissimilar orthotropic composite materials under in-plane and anti-plane loading conditions
is investigated. In the analytical model, orthotropic half-spaces are assumed to be bound together by a matrix interlayer
which represents the matrix-rich interlaminar region in the fiber-reinforced composite laminate. The crack is embedded within
the interlayer. With the utilization of the stiffness matrix approach, a system of singular integral equations of the first
kind is derived for the current mixed boundary value problem. Numerical results are obtained for the interlaminar crack in
a [0°/90°] fibrous composite laminate subjected to three basic loadings in fracture mechanics. Under each applied loading,
variations of major and coupling stress intensity factors with respect to relative crack size, crack location, and fiber volume
fraction are illustrated. 相似文献
7.
Anti-plane shear crack in a functionally gradient piezoelectric layer bonded to dissimilar half spaces 总被引:4,自引:0,他引:4
In this paper, the problem of a crack located in a functionally gradient piezoelectric interlayer between two dissimilar homogeneous piezoelectric half-planes being subjected to an anti-plane mechanical loading and an in-plane electric loading is considered. The material properties of the interlayer, such as the elastic stiffness, piezoelectric constant and dielectric constant, are assumed to vary continuously along the thickness of the interlayer, and the crack surface condition is assumed to be impermeable or permeable. By using the Fourier transform, the problem is first reduced to two pairs of dual integral equations and then into a Fredholm integral equation of the second kind. Numerical calculations are carried out, and the effects of crack geometric parameters on the stress intensity factor and the energy release rate are shown graphically. 相似文献
8.
The problem of three collinear interfacial cracks between two dissimilar transversely isotropic piezoelectric materials is considered under electromechanical loadings. The crack surfaces are assumed to be impermeable to the electric field. A single antiplane mechanical and inplane electrical loads are applied at a point on centred crack surface. The problem is formulated by the complex function method, and reduced to the vector Hilbert problem. By solving the problem, a closed form solution for the stress intensity and electric displacement intensity factor is obtained. This solution can be used as a Green’s function for different loading conditions. 相似文献
9.
Kwang Ho Lee Young Jae Lee Sang Bong Cho 《Journal of Mechanical Science and Technology》2009,23(5):1306-1322
When a crack propagates with acceleration, deceleration and time rates of change of stress intensity factors, it is very important
for us to understand the effects of acceleration, deceleration and time rates of change of stress intensity factors on the
individual stresses and displacements at the crack tip. Therefore, the crack tip stress and displacement fields for a transiently
propagating crack along gradient in functionally graded materials (FGMs) with an exponential variation of shear modulus and
density are developed and the characteristics of a transiently propagating crack from the fields are analyzed. The effects
of the rate of change of the stress intensity factor and the crack tip acceleration on the individual stresses at the crack
tip are opposite each other. Specially, the isochromatics (constant maximum shear stress) of Mode I tilt backward around the
crack tip with an increase of crack tip acceleration, and tilt forward around the crack tip with an increase of the rate of
change of the dynamic mode I stress intensity factor.
This paper was recommended for publication in revised form by Associate Editor Chongdu Cho
Kwang-Ho Lee received a Ph.D. degree in Yeungnam University in 1993. Dr. Lee is currently a professor at the School of Mechanical and
Automotive Engineering at Kyungpook National University in Korea. He also had worked in KOMSCO as an engineer and researcher
(1982.3–1996.2). He is interested in the fields of fracture and stress analysis on the composite, interface, nano and functionally
graded materials by theoretical and experimental mechanics. Specially, his major interest is analysis of dynamic crack tip
fields.
Young-Jae Lee received his B.S degree in Agricultural Civil Engineering from Gyeongsang National University (GNU) in 1982. He then received
his M.S. and Ph.D. degrees from GNU in 1984 and 1995, respectively. Dr. Lee is currently a professor at the department of
Civil Engineering at Kyungpook National University in Korea. From 2005 to 2006, he had served as an editor of Korea Institute for Structure Maintenance and Inspection. His research interests are in the area of evaluation, diagnosis and optimum design of structure.
Sang-Bong Cho received a Ph. D. degree from Tokyo University in 1989. Dr. Cho is currently a professor at the division of Mechanical and
Automation Engineering at Kyungnam University in Korea. His research interests are in the area of fracture mechanics, FEM
stress analysis and fretting fatigue. 相似文献
10.
Hyung Jip Choi 《Journal of Mechanical Science and Technology》2001,15(10):1386-1397
In this paper, the plane elasticity equations are used to investigate the in-plane normal (mode I) and shear (mode II) behavior of a crack perpendicular to and terminating at the interface in bonded media with a graded interfacial zone. The interfacial zone is treated as a nonhomogeneous interlayer with the continuously varying elastic modulus between the two dissimilar, homogeneous semi-infinite constituents. For each of the individual loading modes, based on the Fourier integral transform technique, a singular integral equation with a Cauchy kernel is derived in a separate but parallel manner. In the numerical results, the values of corresponding modes of stress intensity factors are illustrated for various combinations of material and geometric parameters of the bonded media in conjunction with the effect of the material nonhomogeneity within the graded interfacial zone. 相似文献