高速运动裂纹的分叉角问题

裂纹在脆性体和准脆性体中高速扩展时的分叉现象,是力学和工程界感兴趣的研究课题之一目前的理论研究从两个角度进行:一个可以称为“分叉后”理论,设裂纹已按所假定的角度分叉,研究分叉后裂纹尖端的动应力场特性。另一个可以称为“分叉前”理论,研究裂纹分叉前其尖端附近动应力场特征,采用某种断裂力学判据确定裂纹分叉条件并预言分叉角。     

含不可渗透边裂纹压电材料反平面问题的解

研究了含边缘裂纹的矩形截面压电材料在平面内电场和反平面荷载作用下的问题。得到了满足拉普拉斯方程、裂纹面边界条件的位移函数解和电势函数解及电弹场的基本解。最后,用边界配置法计算了能量释放率。本文提出的这种半解析半数值的方法计算简便,而且具有广泛的应用性。     

压电材料反平面裂纹自相似扩展分析

通过对耦合的波动方程和调和方程解耦,用自模拟方法研究了压电材料中反平面裂纹的自相似扩展问题.研究表明: 对反平面问题,介质内的耦合场与裂纹扩展速度有关,在裂纹尖端有r-1/2阶的奇异性; 动态应力强度因子与电位移载荷有关,与静态结论不同; 电位移强度因子与机械载荷无关, 与静态结果的表达形式一致.     

非均匀弹性材料中反平面的运动裂纹

用解析方法研究了非均匀弹性材料中反平面运动裂纹问题。首先采用余弦变换求解非均匀材料的基本方程，然后根据混合边值条件建立裂纹运动的对偶积分方程，再把对偶积分方程化为第二类Fredholm积分方程。给出了数值算例，计算结果表明材料的非均匀性对动应力强度因子有较大的影响。     

含圆孤裂纹系的压电材料反平面应变问题

应用复变函数解析延展原理，并通过求解Ｒｉｅｍａｎｎ－Ｈｉｌｂｅｒｔ问题，得到了含圆弧裂纹压电材料反平面应变问题的一般解，对单个圆弧裂纹的情形，给出了封闭形式的复函数解和场强度因子，结果表明，当无限远处或裂纹表面同时受机械载荷（应力τ＾∞或Ｔｚ）和电载荷（电位移Ｄ＾∞或电荷ｑ）联合作用时，应力强度因子仅与机械载荷有关，而电位移动强度因子仅与电载荷有关。     

双周期裂纹压电材料反平面剪切问题断裂力学分析

研究压电材料双周期裂纹反平面剪切与平面电场作用的问题．运用复变函数方法，获得了该问题严格的闭合解，并由此给出了裂纹尖端应力强度因子和电位移强度因子的精确公式．数值算例显示了裂纹分布特征对材料断裂行为的重要影响．叠间小裂纹能够对主裂纹的应力和电位移场起着屏蔽作用，相反行间小裂纹却起着放大作用，至于钻石形分布裂纹的影响规律则更为复杂．对于某些特殊情形给予了解答并导出一系列有意义的结果。     

压电材料反平面应变状态的椭圆夹杂及界面裂纹问题

本文采用共法求解了压电材料反平面变形的椭圆夹杂及界面裂纹问题，前者的解答表明当远场外力均匀分布对夹杂内的应力场及电位移场是常量，后者解答表明在界面裂纹的裂尖处，应力及电位移都具有γ＾－１／２的奇异性。     

各向异性压电材料平面裂纹的耦合场分析

用Stroh方法分析了各向异性压电材料电导通型裂纹问题的耦合场.结果表明,裂纹面上的切向电场强度和法向电位移均为常数,在裂纹尖端有由弹性场的耦合作用产生的奇异;电导通裂纹模型中的静电场对裂纹尖端扩展的能量释放率不作贡献.     

功能梯度压电材料反平面裂纹问题

基于三维弹性理论和压电理论，导出了材料系数在横观各向同性平面内梯度分布的压电体的状态方程，进而对材料系数指数函数规律分布的半无限大压电体中的反平面裂纹问题进行了求解，利用Fourier变换给出了半无限大压电体中位移，应力，电势及电位移的解析表达式，并求得了裂纹尖端的应力强度因子和电位移强度因子，分析了不同的非均匀材料系数及几何尺寸对它们的影响。     

不同材料界面共圆弧裂纹的反平面问题

本文首次将不同弹性材料界面共圆弧裂纹版平面问题,化为解析函数边值问题,获得了一般解答,由此求出了几种典型情况的精确解,算出了应力强度因子。当两种材料相同时,本文结果与文[S]完全吻合。     

含中心裂纹压电体的二维精确解

解析地研究了含中心裂纹的压电体，它在无穷远处承受机电载荷，并在裂面上满足由Parton和Kudryavtsev以及Hao和Shen提出的绝对电边界条件。在平面应变假设下，给出其二维精确解，并提供了机械应变能释放率和裂尖能量释放率等数值结果。考虑工业应用范围之内常用的远场载荷时，由绝对电边界条件得出的能量释放率表现出明显的非线性特征及载荷相关性，而不是完全与电场无关，这一结论与Xu和Rajapakse在较小载荷下得到的规律不同。     

Dynamic fracture mechanics analysis for composite material with material non-homogeneity in thickness direction

The problem considered here is the response of a non-homogeneous composite material containing some cracks subjected to dynamic loading. It is assumed that the composite material is orthotropic and all the material properties depend only on the coordinatey (along the thickness direction). In the analysis, the elastic region is divided into a number of plies of infinite length. The material properties are taken to be constants for each ply. By utilizing the Laplace transform and Fourier transform technique, the general solutions for plies are derived. The singular integral equations of the entire elastic region are obtained and solved by the virtual displacement principle. Attention is focused on the time-dependent full field solutions of stress intensity factor(SIF) and strain energy release rate. As a numerical illustration, the dynamic stress intensity factor of a substrate/functionally graded film structure with two cracks under suddenly applied forces on cracks face are presented for various material non-homogeneity parameters.     

Coupled solution for anisotropic piezoelectric materials with cracks

The coupled elastic and electric fields for anisotropic piezoelectric materials with electrically permeable cracks are analyzed by using Stroh formula in anisotropic elasticity. It is shown from the solution that the tangent component of the electric field strength and the normal component of the electric displacement along the faces of cracks are all constants, and the electric field intensity and electric displacement have the singularity of type (1/2) at the crack tip. The energy release rate for crack propagation depends on both the stress intensity factor and material constants. The electric field intensity and electric displacement inside electrically permeable cracks are all constants.     

Electroelastic interaction between a piezoelectric screw dislocation and a confocal elliptic blunt crack with elliptical inhomogeneity

The electroelastic interaction between a piezoelectric screw dislocation and an elliptical inhomogeneity containing a confocal blunt crack under infinite longitudinal shear and in-plane electric field is investigated. Using the sectionally holomorphic function theory, Cauchy singular integral, singularity analysis of complex functions and theory of Rieman boundary problem, the explicit series solution of stress field is obtained when the screw dislocation is located in inhomogeneity. The intervention law of the interaction between blunt crack and screw dislocation in inhomogeneity is discussed. The analytical expressions of generalized stress and strain field of inhomogeneity are calculated, while the image force, field intensity factors of blunt crack are also presented. Moreover, a new matrix expression of the energy release rate and generalized strain energy density (SED) are deduced. With the size variation of blunt crack, the results can be reduced to the case of the interaction between a piezoelectric screw dislocation and a line crack in inhomogeneity. Numerical analysis are then conducted to reveal the effects of the dislocation location, the size of inhomogeneity and blunt crack and the applied load on the image force, energy release rate and strain energy density. The influence of dislocation on energy release rate and strain energy density is also revealed.     

动静荷载对邻近巷道裂纹缺陷扰动的模拟实验

为了探究动静组合应力场作用下邻近巷道背爆侧裂纹缺陷的扩展规律,采用动静加载透射式动态焦散线方法进行了模拟实验,并结合裂纹尖端的动态应力强度因子和能量释放率进行了分析。实验结果表明:在动静荷载作用下,邻近巷道背爆侧裂纹缺陷处也成为巷道主要扰动区,且爆炸荷载对背爆侧预制裂纹的起裂起主导作用;p=0.2 MPa时的相同动静组合应力场中,背爆侧预制裂纹的扩展位移差异与裂纹的倾角有关,当θ=75°时,爆炸应力波无法驱动裂纹起裂;在相同爆炸荷载作用下,θ=30°时,较小竖向荷载对裂纹的扩展具有抑制作用,且抑制作用随所施加的竖向荷载增加而增大,当p=0.4 MPa时,裂纹无法起裂;裂纹最终扩展位移,与裂纹尖端动态应力强度因子在极大值上下振荡变化的持续时间,或在裂纹扩展阶段能量释放率积累量,呈正相关。     

压电复合材料中正n边形孔边裂纹的反平面问题研究

本文基于Cauchy积分理论和Schwarz-Christoffel(SC)变换技术,针对压电复合材料中带一条裂纹的正n边形孔口缺陷的反平面断裂力学进行了探究.假设满足电不可通边界条件,利用Cauchy积分公式和留数定理,获得了任意正n边形裂尖处应力和电位移两个场强度因子以及全能量释放率的封闭形式的显式解.当正n边形边...     

A closed form solution for stress intensity factors of shear modes for 3-D finite bodies with cracks by energy release rate method

In this paper, a new analytical-engineering method of closed form solution for stress intensity factors of shear modes for 3-D finite bodies with cracks is derived by the time saving energy release rate method. Hence a complete series of useful results of stress intensity factorsK _II andK _III can be obtained. And the results provided by this method are in good agreement with some obtained by other methods.     

Analysis of complex stress intensities for cracked laminates

ＡＮＡＬＹＳＩＳＯＦＣＯＭＰＬＥＸＳＴＲＥＳＳＩＮＴＥＮＳＩＴＩＥＳＦＯＲＣＲＡＣＫＥＤＬＡＭＩＮＡＴＥＳＨｕＨｕｒａｎｇ（胡互让）;ＷｕＣｈｅｎｇｐｉｎｇ（吴承平）（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａｎｉｃａｌ．ＡｅｒｏｓｐａｃｅａｎｄＭａｎｕｆａ...     

Dynamic anti-plane shear of a cracked piezoelectric ceramic

The dynamic theory of antiplane piezoelectricity is applied to solve the problem of a line crack subjected to horizontally polarized shear waves in an arbitrary direction. The problem is formulated by means of integral transforms and reduced to the solution of a Fredholm integral equation of the second kind. The path-independent integral G is extended here to include piezoelectric effects, and is evaluated at the crack tip to obtain the dynamic energy release rate. Numerical calculations are carried out for the dynamic stress intensity factor and energy release rate. The material is piezoelectric ceramic.     

压电压磁复合材料中正六边形孔边裂纹的反平面断裂问题

基于线性磁电弹性理论,利用Schwarz-Christoffel(CS)变换技术和Stroth公式,首次系统研究了压电压磁复合材料中含带两个不对称裂纹的正六边形孔口问题在部分渗透磁电边界条件下的解析解.当忽略磁场时,磁电非渗透裂纹和磁电渗透裂纹两种极端情况下的解析解答可退化为文献已有研究结果.数值结果揭示了正六边形孔口尺寸、裂纹长度以及力电载荷和磁载荷对能量释放率的影响规律.研究结果表明：减小孔口边长和裂纹长度可以提高材料的可靠性;机械载荷总是促进裂纹扩展;在磁电非渗透和磁电部分渗透边界条件下,负电场和负磁场会延缓裂纹的扩展,而正电场可以增强或阻碍裂纹的扩展,这取决于所施加的电场和磁场的强度以及机械载荷的水平;在磁电渗透边界条件下,电场和磁场对裂纹的扩展没有影响.