一维正方准晶垂直于准周期方向具有不对称共线裂纹的圆形孔口问题

利用复变函数方法,通过构造广义保角映射,研究了一维正方准晶垂直于准周期方向具有不对称共线裂纹的圆形孔口问题,给出了各应力分量在象平面的复表示,并得到该裂纹尖端的应力强度因子.在极限情形下,给出一维正方准晶中具有对称共线裂纹的圆形孔口,带单裂纹的圆形孔口和Griffith裂纹在裂纹尖端的应力强度因子.     

一维六方准晶中具有不对称裂纹的圆形孔口问题的解析解

利用复变函数方法,通过构造保角映射,研究了一维六方准晶中具有不对称裂纹的圆形孔口的反平面剪切问题,给出了Ⅲ型裂纹问题的应力强度因子的解析解,在极限情形下,不仅可以还原为已有的结果,而且求得一维六方准晶中具有对称裂纹的圆形孔口问题,带裂纹的圆形孔口问题在裂纹尖端的应力强度因子解析解.仅声子场而言,所得结果与经典弹性的结果完全一致.     

带k条径向边裂纹的圆形孔口问题的应力分析

利用复变函数方法,通过构造保角映射研究了带k条径向边裂纹的圆形孔口的平面弹性问题,给出了裂纹尖端Ⅰ型与Ⅱ型问题应力强度因子的精确分析解.在极限情况下,不仅可以还原出星形裂纹,Griffith裂纹,十字裂纹等经典的裂纹问题的结果,而且当k取任意正整数值时,可以模拟出更多的、复杂的带裂纹的圆形孔口问题.     

一维六方准晶中带双裂纹的椭圆孔口问题的解析解

利用复变函数方法,通过构造保角映射,研究了一维六方准晶中带双裂纹的椭圆孔口的反平面剪切问题,给出了Ⅲ型裂纹问题的应力强度因子,在极限情形下,不仅可以还原为已有的结果,而且求得一维六方准晶中带双裂纹的圆形孔口问题、十字裂纹问题在裂纹尖端的应力强度因子．     

一维六方准晶中带三条不对称裂纹的圆形孔口问题的解析解

利用复变函数方法,通过构造保角映射,研究了一维六方准晶中带不对称三裂纹的圆形孔口的反平面剪切问题,给出了Ⅲ型裂纹问题的应力强度因子,在极限情形下,不仅可以还原为已有的结果,而且求得一维六方准晶中L裂纹问题在裂纹尖端的应力强度因子.     

圆形孔口裂纹的反平面剪切问题的解析解

利用复变函数方法,通过构造保角映射,研究了带裂纹的圆形孔口的反平面剪切问题,给出了Ⅲ型裂纹问题的应力强度因子.在极限情形下,求得Griffith裂纹在裂纹尖端处应力强度因子,这与已有的结果完全一致.最后数值算例给出了半经和裂纹长度对应力强度因子的影响.     

含圆形孔口和水平直裂纹的平面问题的应力分析

利用复变函数方法和积分方程理论研究了既含有圆形孔口又含有水平裂纹的无限大平面的平面弹性问题,将复杂的解析函数的边值问题化成了求解只在裂纹上的奇异积分方程的问题.此外,还给出了裂纹尖端附近的应力场和应力强度因子的公式.     

任意形状孔口单边裂纹问题的边界配位解法

本文提出了一组复应力函数,采用边界配位方法对不同形状孔口(包括圆、椭圆、矩形及菱形孔口)的单边裂纹平板的应力强度因子进行了计算.计算结果表明,对长度和宽度远大于孔口和裂纹几何尺寸的试件,配位法与用其他方法所得的无限大板含圆或椭圆孔边裂纹问题的解符合得很好.同时,对其他孔口问题,特别是有限大板情形,本文给出了一系列计算结果.本文所提出的函数及计算过程可以应用于任意形状孔口单边裂纹平板的计算.     

一维正交准晶中具有四条裂纹的椭圆孔口问题的解析解

运用广义复变函数方法,通过构造适当的广义保角映射,研究了一维正交准晶中具有四条裂纹的椭圆孔口的平面弹性问题.通过引入应力函数,把平面弹性问题的基本方程简化为一个四阶偏微分方程,从而给出了各个应力分量在像平面的复表示,求得了裂纹尖端的应力强度因子的解析解.当描述缺陷的各参数发生变化时,该文的结果不仅可以还原已有文献中的结论,还可给出多种常见缺陷构型的应力强度因子,为工程力学分析提供了理论依据.     

一维六方压电准晶双材料界面共线裂纹问题北大核心CSCD

利用复变函数理论中的解析延拓、奇性主部分析和推广的Liouville定理,求解了一维六方压电准晶双材料在集中载荷作用下界面共线裂纹反平面弹性问题.导出了含有一条和两条有限长界面裂纹的封闭解,同时给出了裂纹尖端场强度因子(包含声子场和相位子场应力强度因子和电位移强度因子)的表达式.数值算例分析了外荷载与耦合系数之比对裂纹尖端场强度因子变化规律的影响.从数值结果中可以看出,当裂纹长度增加时,裂纹尖端场强度因子随之增加;应力强度因子随双材料耦合系数之比的增大而增大,电位移强度因子几乎不变;不同载荷作用下,裂纹尖端场强度因子随着裂纹长度改变时的变化趋势也不尽相同.研究结果可为压电准晶双材料的设计和制备提供一定的理论参考.     

Crack-tip-opening displacement for four symmetrically situated cracks with coalesced interior yield zones

Crack-tip opening displacements are obtained for four collinear straight cracks, weakening an unbounded homogeneous and isotropic elastic-perfectly plastic plate. The cracks are so configured that two symmetrically situated and interiorly lying cracks are of equal-lengths. Other two exteriorly lying, collinear straight cracks (surrounding the interiorly lying straight cracks) are of mutually equal-lengths. Thus an exterior and an interior crack-set are symmetrically oriented with respect to the other interior–exterior collinear cracks-set configuration. Uniform constant load prescribed at remote boundary of the plate, opens the crack in self-similar fashion developing a strip-yield zone ahead each tip of the cracks. It is assumed that the strip-yield zone developed at each of interior tips of an exteriorly and interiorly lying crack-set configuration gets coalesced. The developed yield zones are subjected to normal cohesive yield stress to arrest the crack from further opening. The solution of the problem is obtained by superposing the solutions of the two auxiliary problems, appropriately derived from the given problem. Each of the auxiliary problems, in turn, is solved using complex variable technique. Expressions are derived for quantities of interest viz. crack-tip opening displacement (CTOD), length of each developed yield zone. The effect of applied load and closing load on the parameters CTOD and strip yield zone affecting the crack arrest is presented graphically and concluded.     

一维六方准晶双材料中圆孔边共线界面裂纹的反平面问题

研究了一维六方准晶双材料中圆孔边不对称共线界面裂纹的反平面问题。利用Stroh公式和复变函数方法得到了声子场和相位子场耦合作用下的复势函数,给出了裂纹尖端应力强度因子和能量释放率的解析表达式。通过数值算例,讨论了圆孔半径和裂纹长度对应力强度因子的影响,以及耦合系数、声子场应力和相位子场应力对能量释放率的影响。结果表明:当圆孔半径不变时,应力强度因子随右裂纹长度的增大趋向稳定值。当相位子场应力取一定值时,能量释放率达到最小值,说明特定的相位子场应力可以抑制裂纹的扩展。     

不同功能梯度压电压磁层状介质中共线界面裂纹的动态性能分挝

对不同功能梯度压电压磁层状介质中,共线界面裂纹对简谐应力波作用下的动态问题,进行了分析.经Fourier变换,使问题的求解转换为求解以裂纹面上位移间断为未知量的三重对偶积分方程,三重对偶方程可以采用Schmidt方法来求解,进而分析了功能梯度参数、入射波频率和层状介质厚度对应力、电位移和磁通量强度因子的影响.     

Stress Concentration in an Anisotropic Half Space with Cylindrical Cavities and Plane Cracks

A method is proposed for determining the two-dimensional stressed state of a half space with a general rectilinear anisotropy. General representations of the complex potentials are obtained and studied, as well as expressions for the stresses and displacements, along with the boundary conditions for determining these functions. As an example, we solve for the stressed state of and calculate the stress intensity factors for a half plane (in the presence of a single elastic symmetry plane) with a circular (elliptical) hole and edge cracks. It is shown how the crack length, the closeness of a hole with a crack to the boundary, and the anisotropy of the material affect the stress concentration and stress intensity factors.     

Crack Arrest Model for a Plate Weakened by Internal and External Cracks - a Modified Dugdale Approach

A modified Dugdale model solution is obtained for an elastic-perfectly-plastic plate weakened by one internal and two external straight collinear hairline cracks. The tension applied to the infinite boundary of the plate opens the rims of cracks with forming a plastic zone ahead of each tip of the internal crack and also at each finitely distant tip of the two external cracks. The developed plastic zones are closed by normal cohesive linearly varying yield-point stress distributions applied to their rims. The problem is solved using the complex-variable technique. A case study is carried out to find the load required to prevent the cracks from further growing with respect to affecting parameters. The results obtained are reported graphically and analyzed.     

Mathematical model for crack arrest of an infinite plate weakened by a finite and two semi-infinite cracks

The problem of an unbounded plate weakened by three quasi-static coplanar and collinear straight cracks: two semi-infinite cracks and a finite crack situated symmetrically between two semi-infinite cracks, is investigated. The plate is subjected to uniform unidirectional in-plane tension at infinite boundary. Developed plastic zones are arrested by distributing cohesive yield point stress over their rims. The solution is obtained using complex variable technique. Closed form analytic expressions are derived for load bearing capacity and crack-tip-opening displacement (CTOD). A case study is presented for CTOD and load bearing capacity versus crack length, plastic zone length and inter-crack distance etc. Results are presented graphically and analyzed.     

Crack opening displacement for two unequal straight cracks with coalesced plastic zones – A modified Dugdale model

The problem investigated is of an infinite plate weakened by two collinear unequal hairline straight quasi-static cracks. Uniform constant tension is applied at infinity in a direction perpendicular to the rims of the cracks. Consequently the rims of the cracks open in Mode I type deformation. The tension at infinity is increased to the limit such that the plastic zones developed at the two adjacent interior tips of cracks get coalesced. To arrest the crack from further opening normal cohesive variable stress distribution is applied on the rims of the plastic zones. Closed form analytic expressions are obtained for load bearing capacity and crack opening displacement (COD). An illustrative case is discussed to study the behavior of load bearing capacity and crack opening displacement with respect to affecting parameters viz. crack length, plastic zone length and inter crack distance between the two cracks. Results obtained are reported graphically and analyzed.     

任意形状孔口双边裂纹平板的应力强度因子计算

本文采用Muskhclishvili弹性力学的复变函数和边界配位方法对不同形状孔口双边裂纹问题进行了研究,计算了圆孔、椭圆孔、矩形孔、菱形孔等不同形状孔口双边裂纹,以及Ⅰ型和复合型等不同类型断裂试件的应力强度因子,本文方法简单方便,精度较高,与某些已有计算结果的问题比较,本文方法所得的结果是令人满意的.同时,本方法可以应用于不同几何形状和加载条件下的孔口双边裂纹有限大板的计算,是解这一类问题的一致有效方法.