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1.
This paper analyzes the asymptotic problem of a kinked crack in an anisotropic material under antiplane deformation. Using
the linear transformation method proposed in this paper, a solution to the asymptotic problem of a kinked crack in an anisotropic
material can be obtained from the solution of the corresponding isotropic kinked crack problem. The exact solution of the
stress intensity factor for the kinked crack in the anisotropic material is obtained from the solution of the isotropic problem.
The effect of the kink angle and two anisotropic parameters on the stress intensity factor is discussed for the inclined orthotropic
material as well as the anisotropic material. In order to verify the exact solution of the stress intensity factor, numerical
calculations are performed by using finite element analysis. 相似文献
2.
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
3.
Hyeon Gyu Beom Kyoung Moon Jeong Eun Do Jeong 《Journal of Mechanical Science and Technology》2002,16(8):1117-1126
A conducting crack in an electrostrictive ceramic under combined electric and mechanical loading is investigated. Analysis
based on linear dielectric model predicts that the surfaces of the crack are not open completely but they are contact near
the crack tip. The complete solution for the crack with a contact zone in a linear electrostrictive ceramic under combined
electric and mechanical loading is obtained by using the complex variable formula. The asymptotic problems for a semi-infinite
crack with a partial opening zone as well as for a fully open semi-infinite crack in a nonlinear electrostrictive ceramic
are analyzed in order to investigate the effect of the electrical nonlinearity on the stress intensity factor under small
scale nonlinear conditions. Particular attention is devoted to a finite crack in the nonlinear electrostrictive ceramic subjected
to combined electric and mechanical loading. The stress intensity factor for the finite crack under small scale nonlinear
conditions is obtained from the asymptotic analysis. 相似文献
4.
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
5.
为提高压电传感器和换能器的品质,针对材料缺陷导致的压电元器件失效或不稳定,用复变函数的方法,结合椭圆形夹杂内的电场强度和电位移为常量这一早期研究结果,研究了压电材料平面电渗透裂纹的机电耦合场及其奇异性。解答表明,切向电场强度和法向电位移在裂纹尖端有由机械载荷引起的奇异,而与电载荷无关;应力强度因子与纯弹性材料结果一致。 相似文献
6.
在不可导通、可导通和半可导通等三种电边界条件下,系统研究并给出三维无限横观各向同性压电介质中平行于各向同性面的、任意形状的平片裂纹在任意载荷作用下的不连续位移和不连续电势边界积分方程方法。无论平片裂纹的形状如何,结果都表明:对不可导通裂纹,应力强度因子只与机械载荷有关,电位移强度因子只与电载荷有关;而可导通裂纹的应力强度因子和电位移强度因子只与机械载荷有关,电位移强度因子由机械载荷通过压电效应产生。半可导通裂纹所对应的边界积分方程组为非线性方程组,文中给出一种迭代解法。在均布的机械载荷和电载荷作用下。裂纹腔内的电位移为一常数,只与外加载荷有关,而与裂纹形状无关。 相似文献
7.
Hyeon Gyu Beom Yu Hwan Kim Chongdu Cho Chang-Boo Kim 《Journal of Mechanical Science and Technology》2006,20(9):1428-1435
A slightly curved crack with an eigenstrain is considered. Solutions for a slightly curved crack in a linear isotropic material
under asymptotic loading as well as for a slightly curved crack in a linear isotropic material with a concentrated force are
obtained from perturbation analyses, which are accurate to the first order of the parameter representing the non-straightness.
Stress intensity factors for a slightly curved crack with an eigenstrain are obtained from the perturbation solutions by using
a body force analogy. Particular attention is given to the crack path stability under mode I loading. A new parameter of crack
path stability is proposed for a crack with an eigenstrain. The path stability of a crack with steady state growth in a transforming
material and a ferroelectric material is examined. 相似文献
8.
Seog Young Han M. N. L. Narasimhan T. C. Kennedy 《Journal of Mechanical Science and Technology》1989,3(2):103-112
The dynamic propagation of a finite crack under mode-1 loading in a micropolar elastic solid is investigated. By using an
integral transform method, a pair of two-dimensional singular integral equations governing stress and couple stress is formulated
in terms of displacement transverse to the crack, macro and micro rotations, and microinertia. These equations are solved
numerically, and solutions for dynamic stress intensity and couple stress intensity factors are obtained by utilizing the
values of the strengths of the square root singularities in macrorotation and the gradient of microrotation at the crack tips.
The motion of the crack tips and the load on the crack surface are not prescribed in the formulation of the problem. Therefore,
the method of solution is applicable to nonuniform rates of propagation of a crack under an arbitrary time-dependent load
on the crack surface. As an example, the diffraction of a micropolar dilatational wave by a stationary crack is considered.
The behavior of the microrotation field and the dynamic couple stress intensity factor, influenced by microinertia, in addition
to the dynamic stress intensity factor, are examined. The classical elasticity solution for the corresponding problem arises
as a special case when the micropolar moduli are dropped from the present solution. 相似文献
9.
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
10.
The problem of a radial crack in cross-ply laminates under uniaxial tension is investigated in this paper. The normalized
stress intensity factors are obtained by the modified mapping collocation method which is based on analytic complex function
theory of complex variables. The present results for an isotropic infinite plate show good agreement with existing solutions.
In the range of small crack length, the stress intensity factor for a radial crack in cross-ply laminates under uniaxial tension
becomes larger as the percentage of 0° plies increases. However in the range of large crack length, it is insensitive to the
percentage of 0° plies. 相似文献
11.
Exact solutions for piezoelectric materials with an elliptic hole or a crack under uniform internal pressure 总被引:3,自引:1,他引:2
The existing investigations on piezoelectric materials containing an elliptic hole or a crack mainly focus on remote uniform tensile loads.In order to have a better understanding for the fracture behavior of piezoelectric materials under different loading conditions,theoretical and numerical solutions are presented for an elliptic hole or a crack in transversely isotropic piezoelectric materials subjected to uniform internal pressure and remote electro-mechanical loads.On the basis of the complex variable approach,analytical solutions of the elastic and electric fields inside and outside the defect are derived by satisfying permeable electric boundary condition at the surface of the elliptical hole.As an example of PZT-4 ceramics,numerical results of electro-elastic fields inside and outside the crack under various electric boundary conditions and electro-mechanical loads are given,and graphs of the electro-elastic fields in the vicinity of the crack tip are presented.The non-singular term is compared to the asymptotic one in the figures.It is shown that the dielectric constant of the air in the crack has no effect on the electric displacement component perpendicular to the crack,and the stresses in the piezoelectric material depend on the material properties and the mechanical loads on the crack surface and at infinity,but not on the electric loads at infinity.The figures obtained are strikingly similar to the available results.Unlike the existing work,the existence of electric fields inside an elliptic hole or a crack is considered,and the piezoelectric solid is subjected to complicated electro-mechanical loads. 相似文献
12.
13.
Kwang Ho Lee Arun Shukla Venkitanarayanan Parameswaran Vijaya Chalivendra Jae Sug Hawong 《Journal of Mechanical Science and Technology》2002,16(2):165-174
In the present study, interfacial cracks between an isotropic and orthotropic material, subjected to static far field tensile
loading are analyzed using the technique of photoelasticity. The fracture parameters are extracted from the full-field isochromatic
data and the same are compared with that obtained using boundary collocation method. Dynamic photoelasticity combined with
high-speed digital photography is employed for capturing the isochromatics in the case of propagating interfacial cracks.
The normalized stress intensity factors for static cracks are greater when α=90° (fibers perpendicular to the interface) than
when α=0° (fibers parallel to the interface), and those when α=90° are similar to ones of isotropic material. The dynamic
stress intensity factors for interfacial propagating cracks are greater when α=0° than α=90°. For the velocity ranges (0.1<c/c
s1
<0.7) observed in this study, the complex dynamic stress intensity factor |K
D
|, I increases with crack speedc, however, the rate of increase of |K
D
| with crack speed is not as drastic as that reported for homogeneous materials. 相似文献
14.
Tae Hyun Baek Lei Chen Dong Pyo Hong 《Journal of Mechanical Science and Technology》2011,25(10):2535-2543
For isotropic material structure, the stress in the vicinity of crack tip is generally much higher than the stress far away
from it. This phenomenon usually leads to stress concentration and fracture of structure. Previous researches and studies
show that the stress intensity factor is one of most important parameter for crack growth and propagation. This paper provides
a convenient numerical method, which is called hybrid photoelasticity method, to accurately determine the stress field distribution
in the vicinity of crack tip and mixed-mode stress intensity factors. The model was simulated by finite element method and
isochromatic data along straight lines far away from the crack tip were calculated. By using the isochromatic data obtained
from finite element method and a conformal mapping procedure, stress components and photoelastic fringes in the hybrid region
were calculated. To easily compare calculated photoelastic fringes with experiment results, the fringe patterns were reconstructed,
doubled and sharpened. Good agreement shows that the method presented in this paper is reliable and convenient. This method
can then directly be applied to obtain mixed mode stress intensity factors from the experimentally measured isochromatic data
along the straight lines. 相似文献
15.
The problem of a crack approaching a circular hole in cross-ply laminates under uniaxial and biaxial loading is investigated
in this paper. The effects of material orthotropy, geometry [R/d and a/d], and loading conditions on crack tip singularity
are investigated. The stress intensity factors are obtained by the modified mapping collocation method. The present results
for an isotropic infinite plate show good agreement with existing solutions. The results for cross-ply laminates show that
the stress intensity factors strongly depend on material orthotropy, geometry, and loading condition. The stress intensity
factors for cross-ply laminates exist between those for θ=0° and those for θ=90° in the whole range of crack length and decrease
as the percentage of 0° plies increases. In the range of small crack length the stress intensity factors for biaxial tension
are higher than those for uniaxial tension. In the range of large crack length the stress intensity factors for uniaxial tension
are higher than those for biaxial tension. 相似文献
16.
We consider the problem of determining the singular stresses and electric fields in a piezoelectric ceramic strip containing a Griffith crack under in-plane normal loading within the framework of linear piezoelectricity. The potential theory method and Fourier transforms are used to reduce the problem to the solution of dual integral equations, which are then expressed to a Fredholm integral equation of the second kind. Numerical values on the field intensity factors are obtained, and the influences of the electric fields for PZT-6B piezoelectric ceramic are discussed. 相似文献
17.
Chang Min Suh Robert O. Ritchie Young Goo Kang 《Journal of Mechanical Science and Technology》1989,3(2):78-85
Fatigue tests by axial loading (R-0.05) were carried out to investigate short fatigue crack growth behavior in 2 1/4 Cr-1 Mo steel at room temperature using smooth and a small notched flat specimen. All the data of the fatigue crack growth rate in the present tests were analyzed as a function of the stress intensity factor equation in conjunction with crack closure behavior. Analysis was performed accounting for the relation of surface effective stress range,Ua and depth effective stress range,Ub. In the case of isotropic crack growth properties,Ub=(ΔKta/ΔKtb) ·Ua. By use ofUb obtained from the analysis, crack growth rates to surface direction coincide with those of depth direction. 相似文献
18.
19.
This study analyzes an interfacial edge crack in an orthotropic thermoelastic bimaterial subjected to uniform heat flux at infinity. The problem is formulated on the basis of transformed function representations of plane solutions for anisotropic thermoelastic solids. The interface stress intensity factors are obtained in terms of four proposed thermal load parameters and two dimensionless coefficient matrices. It is shown that one of the coefficient matrices depends on eight material parameters whereas the other coefficient matrix is affected by only six material parameters. The orthotropic rescaling technique is used to examine the explicit dependence of the two coefficient matrices on one orthotropic material parameter. The effects of the other material parameters on the coefficient matrices are examined numerically. The energy release rate and mode mixity for the interface crack are also obtained. 相似文献
20.
Jeong Woo Shin Soon Man Kwon Kang Yong Lee 《Journal of Mechanical Science and Technology》2001,15(1):21-25
We consider the problem of determining the singular stresses and electric fields in a piezoelectric ceramic strip containing
a Griffith eccentric crack off the center line under anti-plane shear loading with the theory of linear piezoelectricity.
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, and the influences of the electric fields for piezoelectric ceramics are discussed. 相似文献