共查询到18条相似文献,搜索用时 187 毫秒
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本文研究了界面裂纹尖端的动态应力场的奇异特性.引入尖端无摩擦接触的界面裂纹模型并采用具有运动边界的控制积分方程.证明了在动态界面裂纹尖端仅存在平方根奇异的应力场.数值结果表明接触区中的正应力确保持为压应力.为表现界面裂纹的动态特性,给出了应力强度因子和裂纹面接触区尺寸的数值结果. 相似文献
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建立并研究一类接触型界面裂纹模型对瞬态弹性波作用下的动态响应问题。文中利用积分变换和积分方程法推导了确定这类问题的奇异积分方程组。采用围道积分技术和切比雪夫多项式展开技术,得到了待定系数的非线性代数方程组。最后给出了裂纹尖端接触区大小和接触应力随时间变化的数值结果,揭示了这种接触裂纹的动力学特性及物理上的合理性。 相似文献
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有限长界面裂纹对冲击载荷的响应 总被引:6,自引:0,他引:6
本文研究了受冲击载荷作用下界面裂纹的瞬态特性。通过引入裂纹尖端附近裂纹面无摩擦接触区,消除了界面裂纹问题中存在的振荡奇异性。由于产生了随时间变化的运动边界,应用积分变换及路径积分方法进行反演,在时间-空间域上给出了问题的控制积分方程。应用chebyshev多项式展开,将问题转化为非线性微分-积分方程组的求解。给出了剪切应力强度因子和裂纹面接触区尺寸的数值结果。所得结果表明,拉伸场中界面裂纹的扩展和剪切失效有密切关系。 相似文献
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奇异积分方程在裂纹体弹性波散射问题中的应用 总被引:5,自引:0,他引:5
结合20多年来国内外的研究成果,评述奇异积分方程在裂纹体弹性波散射问题中的应用,特别是在界面裂纹散射问题中的应用.讨论如何将裂纹散射问题归结为奇异积分方程、如何用数值法求解这些方程等问题,并指出奇异积分方程法与其他积分方程法的关系.最后展望了奇异积分方程在裂纹体散射问题中可能的应用前景 相似文献
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应用有限部积分概念和广义位移基本解,垂直于磁压电双材料界面三维复合型裂纹问题被转
化为求解一组以裂纹表面广义位移间断为未知函数的超奇异积分方程问题. 进而,通过主部
分析法精确地求得裂纹尖端光滑点附近的奇性应力场解析表达式. 然后,通过将裂纹表面
位移间断未知函数表达为位移间断基本密度函数与多项式之积,使用有限部积分法对超奇异
积分方程组建立了数值方法. 最后,通过典型算例计算,讨论了广义应力强度因子的变化规
律. 相似文献
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本文研究了含非完整界面的功能梯度压电复合材料的Ⅲ型裂纹问题.此裂纹垂直于非完整界面,采用弹簧型力电耦合界面模型模拟非完整界面.界面两侧材料的性质,如弹性模量、压电常数和介电常数均假定呈指数函数形式且沿着裂纹方向变化.运用积分变换法将裂纹面条件转换为奇异积分方程,并使用Gauss-Chebyshev方法对其进行数值求解.根据算例结果讨论了一些退化问题并分析了裂纹尖端强度因子与材料的非均匀系数和非完整界面参数的关系. 相似文献
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本文研究一类粘着型界面裂纹的弹性波散射问题。文中利用积分变换和积分方程方法推导了确定这类问题的奇异积分方程。采用围道积分技术和切比雪夫多项式展开技术,得到了待定系数的非线性代数方程组。最后本文给出裂纹尖端站着区的大小和界面应力的数值结果。 相似文献
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《International Journal of Solids and Structures》2006,43(5):1159-1188
Solution of Cauchy-type singular integral equations permits the evaluation of the fracture parameters at the crack tips very accurately. However, it does not permit the determination of the crack opening and sliding displacements while ensuring no crack surface interpenetration unless the location of the contact zone is known a priori. In order to circumvent this shortcoming, this study presents a solution method based on the Hadamard-type singular integral equations to obtain the crack opening and sliding displacements directly while enforcing the appropriate conditions to prevent interpenetration. Furthermore, the crack opening displacements are physically more meaningful and readily validated against the finite element analysis predictions. The numerical solutions of the hypersingular integral equations provide not only crack opening and sliding displacements directly but also the stress intensity factors and energy release rates. Also, the behavior of the energy release rate is examined as the cohesive crack located parallel to the interface approaches the interface from either the soft or the stiff side of the interface. The limiting value of the energy release rate is established by considering an interface crack. As the cohesive crack approaches the interface from either side of the interface, the energy release rate approaches to that of the interface crack. However, the length of contact zone between the cohesive crack surfaces under uniform shear loading does not approach to that of the interface crack. 相似文献
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Crack problems for isotropic/orthotropic two-layered strips have been investigated. A system of two singular integral equations
can be derived by using Fourier integral transformation and boundary conditions of crack problems. After stress singularities
at crack tips or other special points are determined for internal and edge cracks, and for cracks terminating at and going
through the interface, the system of singular integral equations is solved numerically by Gauss-Jacobi or Gauss-Chebyshev
integration formulas for stress intensity factors at the tips and other singular points of cracks. Finally, possible crack
growth behavior for cracks approaching and going through the interface is discussed. 相似文献
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《International Journal of Solids and Structures》1999,36(16):2463-2479
The interface crack problem of a bimaterial thermopiezoelectric solid was treated byapplying the extended version of Strohs formalism and singular integral equation approach. Theinterface crack considered is subjected to combined thermal, mechanical and electric loads.Under the applied loading, the interface crack is assumed to be partially opened. Formulation ofthe problem results in a set of singular integral equations which are solved numerically. Thestudy shows that the contact zone is extremely small in comparison with the crack length. Basedon the formulation, some physically meaningful quantities of interest such as stress intensityfactors and size of contact zone for a particular material group are analyzed. 相似文献
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The interaction of a general plane P wave and an elastic cylindrical inclusion of infinite length partially debonded from
its surrounding viscoelastic matrix of infinite extension is investigated. The debonded region is modeled as an arc-shaped
interface crack between inclusion and matrix with non-contacting faces. With wave functions expansion and singular integral
equation technique, the interaction problem is reduced to a set of simultaneous singular integral equations of crack dislocation
density function. By analysis of the fundamental solution of the singular integral equation, it is found that dynamic stress
field at the crack tip is oscillatory singular, which is related to the frequency of incident wave. The singular integral
equations are solved numerically, and the crack open displacement and dynamic stress intensity factor are evaluated for various
incident angles and frequencies.
The project supported by the National Natural Science Foundation of China (19872002) and Climbing Foundation of Northern Jiaotong
University 相似文献
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折线型裂纹对SH波的动力响应 总被引:1,自引:0,他引:1
利用Fourier积分变换方法,得出了无限平面中用裂纹位错密度函数表示的单裂纹散射场.根据无穷积分的性质,把单裂纹的散射场分解为奇异部分和有界部分.利用单裂纹的散射场建立了折线裂纹在SH波作用下的Cauchy型奇异积分方程.根据折线裂纹散射场和所得的积分方程讨论了裂纹在折点处的奇性应力及折点处的奇性应力指数.利用所得的奇性应力定义了折点处的应力强度因子.对所得Cauchy型奇积分方程的数值求解,可得裂纹端点和折点处的动应力强度因子。 相似文献
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Dynamic stress intensity factors of two collinear mode-III cracks perpendicular to and on the two sides of a bi-FGM weak-discontinuous interface 总被引:3,自引:0,他引:3
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. 相似文献
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The singularity behavior of a crack on the interface of two different media under dynamic load is investigated. By introducing a small region in which the crack faces make frictionless contact and making use of a kind of integral equations with moving boundaries, it is proved that there are only square-root singularities near the interface crack tips in case that a dynamic load acts on it. Numerical results show that the normal stress in the contact region remains negative. The results of the stress intensity factor and the length of the crack face contact region are given to illustrate the dynamic behavior of the interface crack.This work is supported by the National Natural Science Foundation of China. 相似文献