Shielding Effect and Emission Criterion of a Screw Dislocation Near an Interfacial

Shielding effect and emission criterion of a screw dislocation near an interracial crisscross crack are dealt with in this paper. Utilizing the conformal mapping technique, the closed-form solutions are derived for complex potentials and stress fields due to a screw dislocation located near the interracial crisscross crack. The stress intensity factor on the crack tips and the critical stress intensity factor for dislocation emission are also calculated. The influence of the orientation of the dislocation and the morphology of the crisscross crack as well as the material elastic dissimilarity on the shielding effect and the emission criterion is discussed in detail. The results show that positive screw dislocations can reduce the stress intensity factor of the interracial crisscross crack tip （shielding effect）. The shielding effect increases with the increase of the shear modulus of the lower half-plane, but it decreases with the increase of the dislocation azimuth angle and the distance between the dislocation and the crack tip. The critical loads at infinity for dislocation emission increases with the increase of emission angle and the vertical length of the crisscross crack, and the most probable angle for screw dislocation emission is zero. The present solutions contain previous results as special cases.     

M.E.Shvez迭代解法及其在力学中的应用

当微分方程中含有微量项时,可用M.E.Shvez迭代法求解。但当微量项出现奇性,或在某一区间内微量项并非微量时。用此法求解将遇到困难。本文针对这类问题,把原M.E.Shvez迭代解法稍加改变。算例表明,用改进了的M.E.Shvez法求解上述问题。其精度比原M.E.Shvez法的有所提高。     

在集中力和集中力偶作用下不同弹性材料圆形界面的裂纹问题

运用推广的Schwarz延拓原理结合对复应力函数的奇性主部分析,求解一类有集中荷载的平面弹性问题,十分有效。文[1]用此方法研究了同种材料的弹性问题。本文把它推广于在集中力和集中力偶作用下不同弹性材料的圆形界面上有多条裂纹的情形,求出了几种典型情况复应力函数的封闭解,算出了应力强度因子,并由此导出一系列特殊解答,其中两个在文[1]、[6]中找到一致结果。     

Problem on circular-arc cracks between bonded dissimilar materials under concentrated force and moment

The method is very efficient by applying extended Schwarz principle integrated with the analysis of the singularity of complex stress functions to solve some plane-elastic problems under concentrated loads, in Ref.[1], this method is used to deal with the elastic problems of homogeneous plane. In this paper, it is extended to the case of dissimilar materials with co-circular cracks under concentrated force and moment. For several typical cases the solutions of complex stress function in closed form are built up and the stress intensity factors are given. From these solutions, we provide a series of particular results, in which two of them coincide with those in Refs. [1] and [6].     

The illustration calculations of second order effects in elastic half-space acted upon by a non-uniform shear load

I.IllustrationsThegeneralsolutionofsecondordereffectsinelastichalfspaceacteduponbyanon-uniformshearloadpresentedbypaperIl]areapplicableforallvalueof6>-l,butareverycomplicated.Asani1lustrationofthemethodwegivebelowthelinearandsecondordersolutionsfor8=l/2.T…     

The general solution of second order effects in elastic half-space acted upon by a non-uniform shear load

I.IntroductionInfiniteelasticitytheorythemathematicalequationsgoverningthedeformationofanisotropiccompressibleelasticmaterialarehighlynonlinear.Asaresult,theexactsolutionsoftheboundaryvalueproblemshavebeenpossibleonlyinsomerestrictedcasesand,oftenapproxim…     

非均匀切向荷载下弹性半空间二阶效应的一般解答*

继文[1],本文运用积分变换方法,获得了可压缩各向同性弹性半空间在非均匀分布的切向荷载下,二阶弹性效应问题的封闭形式一般解答.     

An approximate method for determing the velocity profile in a laminar boundary-layer on flat plate

１ＩｎｔｒｏｄｕｃｔｉｏｎａｎｄｔｈｅＳｅｌｅｃｔｉｏｎｏｆｔｈｅＴｒｉａｌＶｅｌｏｃｉｔｙＰｒｏｆｉｌｅＦｕｎｃｔｉｏｎＴｈｅｋｅｙｏｆｔｈｅｉｎｔｅｇｒａｔｉｏｎｍｅｔｈｏｄｏｆｔｈｅｌａｍｉｎａｒｂｏｕｎｄａｒｙ＿ｌａｙｅｒｏｎａｆｌａｔｐｌａ...     

热偶极子与圆形界面裂纹的作用

热偶极子由热源和热汇组成.应用解析延拓方法、广义Liouville 定理及Muskhelishvili 边值问题理论,研究了在热源偶极子作用下含圆形夹杂复合材料的界面裂纹问题.导出温度场和应力场之后,分析了温度场和夹杂对界面断裂的效应.作为实例,针对若干种组合材料及热偶极子处于不同位置,给出了界面裂纹热应力强度因子的数值变化曲线.结果表明,界面裂纹特性取决于材料的弹性常数和热学性能及偶极子的情况.     

Behavior of an Extended Dislocation near an Elliptical Blunt Crack

The behavior of an extended dislocation near an elliptical blunt crack is investigated. The equilibrium separation between Shockley partials and the critical value of stacking fault energy for the formation of extended dislocations by dissociation reaction as well as the extended dislocation emission criterion are developed. The results show that the equilibrium separation increases as the extended dislocation tends to the blunt crack. If the stacking fault energy is comparable to the critical energy for dissociation in a perfect medium, complete dislocations can dissociate to form extended dislocations near the blunt crack. The critical stress intensity factor （SIF） for extended dislocation emission increases with the stacking fault energy and the curvature radius of the blunt crack tip. Moreover, the critical SIF for extended dislocation emission is far lower than the critical SIF for edge dislocation emission.