共查询到20条相似文献,搜索用时 31 毫秒
1.
Hyeon Gyu Beom Do Ryun Lee Hyun Seok Jang 《Journal of Mechanical Science and Technology》2012,26(11):3469-3477
The asymptotic problem of a conducting crack emanating from the vertex of a wedge in an anisotropic dielectric material under purely electric loading is investigated. The wedge crack in an isotropic material is solved using a conformal mapping technique. The solution of the wedge crack in an anisotropic dielectric material is obtained from that for the transformed isotropic problem after applying a linear transformation method. The electric field intensity factor for the anisotropic wedge crack is obtained in the closed form. The effects of crack and wedge angles as well as anisotropic parameters on the electric field intensity factor are illustrated. The electric field intensity factor is numerically calculated by using the J integral and finite element analysis to validate the exact solution of the electric field intensity factor. 相似文献
2.
This study is concerned with the general solution of the field intensity factors and energy release rate for a Griffith crack
in a piezoelectric ceramic of finite radius under combined anti-plane mechanical and in-plane electrical loading. Both electrically
continuous and impermeable crack surface conditions are considered. Employing Mellin transforms and Fourier series, the problem
is reduced to dual integral forms. The solution to the resulting expressions is expressed in terms of Fredholm integral equation
of the second kind. The solutions are provided to study the influence of the crack length, the crack surface boundary conditions
on the intensity factors and the energy release rate. 相似文献
3.
Bing Yang Zhanjiang Wei Zhen Liao Shuwei Zhou Shoune Xiao Tao Zhu Guangwu Yang Mingmeng Wang 《机械工程学报(英文版)》2021,34(4):196-207
In the digital image correlation research of fatigue crack growth rate,the accuracy of the crack tip position determines the accuracy of the calculation of the stress intensity factor,thereby affecting the life prediction.This paper proposes a Gauss-Newton iteration method for solving the crack tip position.The conventional linear fitting method provides an iterative initial solution for this method,and the preconditioned conjugate gradient method is used to solve the ill-conditioned matrix.A noise-added artificial displacement field is used to verify the feasibility of the method,which shows that all parameters can be solved with satisfactory results.The actual stress intensity factor solution case shows that the stress intensity factor value obtained by the method in this paper is very close to the finite element result,and the relative error between the two is only-0.621%;The Williams coefficient obtained by this method can also better define the contour of the plastic zone at the crack tip,and the maximum relative error with the test plastic zone area is-11.29%.The relative error between the contour of the plastic zone defined by the conventional method and the area of the experimental plastic zone reached a maximum of 26.05%.The crack tip coordinates,stress intensity factors,and plastic zone contour changes in the loading and unloading phases are explored.The results show that the crack tip change during the loading process is faster than the change during the unloading process;the stress intensity factor during the unloading process under the same load condition is larger than that during the loading process;under the same load,the theoretical plastic zone during the unloading process is higher than that during the loading process. 相似文献
4.
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
5.
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
6.
The stress field that results from two bodies in contact is an important aspect that governs the fretting fatigue behavior of materials. Applied loads as well as contact geometries influence the contact stresses. The profile of an indenter and the boundary conditions provide sufficient information from which the surface tractions and the corresponding subsurface stresses have been calculated in a semi-infinite halfspace using singular integral equations. In this investigation, a numerical subroutine was developed to calculate the surface tractions and the corresponding surface and subsurface stresses of an arbitrary finite thickness infinite plate subjected to loading through a random indenter. The results from the detailed stress analysis of the contact region are required by both an initiation and fracture mechanics approach. While initiation criteria involving stress gradient fields, such as sharp notches and edges of contact in fretting fatigue, are not well established or agreed upon, stress intensity factor calculations using tools such as weight functions are more reliable. The stress intensity analysis, which is used to determine whether an initiated crack will continue to grow if it is above the threshold, depends on many variables in the stress analysis such as pad and specimen geometry, loading configuration and friction coefficient. The contact stress analysis has been used to determine equivalent stress parameters that are related to the initiation of a crack. Similarly the numerical subroutine for the contact stresses is used in conjunction with the stress intensity analysis to determine the influence of the geometry, loading configuration and friction coefficient on the stress intensity factor. Results from high-cycle fretting fatigue experiments are used to determine the threshold stress intensity factor for a given configuration. The combination of the numerical and experimental analysis is then used to develop a tool for high-cycle fretting fatigue based on a threshold approach involving a go–no go criterion. 相似文献
7.
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
8.
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
9.
疲劳裂纹闭合的数值模拟方法 总被引:5,自引:0,他引:5
用弹塑性有限元法模拟含中心裂纹试件在等幅循环拉伸应力作用下的疲劳裂纹扩展过程,对塑性变形导致的裂纹闭合效应进行了分析。试件材料为2024-T351铝合金板,平面应力状态,线性随动强化假设。分析中考虑裂纹面的弹塑性接触和几何非线性变形,通过逐步释放裂尖节点来模拟裂纹扩展。考察了裂尖局部网格单元尺度、裂纹长度和平均应力对裂纹张开/闭合应力水平的影响。裂纹闭合效应会随疲劳裂纹长度增加而逐渐增强,呈先爬升再缓慢下降的趋势,应力比的增大会导致裂纹张开/闭合应力水平提高。此外,网格细度也对张开/闭合应力的大小有一定影响。 相似文献
10.
Kim K Forest B Geringer J 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2011,225(12):1158-1168
This paper describes a two-dimensional (2D) finite element simulation for fracture and fatigue behaviours of pure alumina microstructures such as those found at hip prostheses. Finite element models are developed using actual Al2O3 microstructures and a bilinear cohesive zone law. Simulation conditions are similar to those found at a slip zone in a dry contact between a femoral head and an acetabular cup of hip prosthesis. Contact stresses are imposed to generate cracks in the models. Magnitudes of imposed stresses are higher than those found at the microscopic scale. Effects of microstructures and contact stresses are investigated in terms of crack formation. In addition, fatigue behaviour of the microstructure is determined by performing simulations under cyclic loading conditions. It is shown that crack density observed in a microstructure increases with increasing magnitude of applied contact stress. Moreover, crack density increases linearly with respect to the number of fatigue cycles within a given contact stress range. Meanwhile, as applied contact stress increases, number of cycles to failure decreases gradually. Finally, this proposed finite element simulation offers an effective method for identifying fracture and fatigue behaviours of a microstructure provided that microstructure images are available. 相似文献
11.
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
12.
Based on the Stroh-type formalism and the technique of conformal mapping, the problem of two non-symmetrical collinear cracks emanating from an elliptical hole in a piezoelectric solid is investigated under remotely uniform in-plane electric loading and anti-plane mechanical loading, which allowed us to take the electric field inside the hole and cracks into account. The analytical solutions of the field intensity factors and the energy release rate are presented in closed-form, which includes the extreme cases for an impermeable crack and a permeable crack. Numerical results are then presented to reveal the effects of geometrical parameters, crack permeability and combined mechanical and electric loadings on the energy release rate. 相似文献
13.
14.
Jin-Shi Wen Woo-Eon Ju Tae-Kyung Han Seung Tae Choi Kyung-Sick Lee 《Journal of Mechanical Science and Technology》2012,26(9):2719-2726
A three-dimensional subsurface penny-shaped crack in an elastic half-space subjected to a compressive moving load is analyzed using the finite element method. The compressive load is applied through a spherical asperity, which moves from left to right on the top surface of the half-space. Normal contact between the crack faces of the penny-shaped crack is modeled using the classical Lagrange multiplier method for constraint enforcement; the tangential contact between the crack faces is assumed to exhibit frictional behavior. Therefore, although the present analysis is limited to a purely linear elastic quasistatic approach, the analysis results show the loading path dependence caused by the frictional contact. Based on linear elastic fracture mechanics, stress intensity factors along the crack front of the penny-shaped crack are evaluated as functions of the crack-front angle, frictional coefficient, normalized load position, and the ratio of the crack depth to the crack length. Finite element analysis shows that shearing-mode failure rather than tearing-mode failure is the dominant cracking mechanism of the penny-shaped crack. This shearing-mode failure tends to occur in the direction of the loading path. 相似文献
15.
Using the theory of linear piezoelectricity, the problem of two layered strip with a piezoelectric ceramic bonded to an elastic material containing a finite interface crack is considered. The out-of-plane mechanical and in-plane electrical loadings are simultaneously applied to the strip. Fourier transforms are used to reduce the problem to a pair of dual integral equations, which is then expressed in terms of a Fredholm integral equation of the second kind. The stress intensity factor is determined, and numerical analyses for several materials are performed and discussed. 相似文献
16.
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
17.
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
18.
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
19.
20.
The stress intensity factors (SIFs) for multiple rolling contact fatigue cracks of a network in the Iran railway under vehicle dynamic load are evaluated in this article. Stress intensity factor evaluation under dynamic loading is simulated in three dimensions using a linear elastic boundary element code. For this purpose, a UIC60 rail with accurate geometry using a boundary element method is studied. A three-dimensional model in Franc3D is provided. Finally, the influence of the friction coefficient between the wheel and rail, crack surface friction, trapped fluid, and initial crack length on SIFs are investigated in detail. 相似文献