位错偶极子和Ⅲ型界面裂纹的干涉效应

研究了多晶体材料中螺型位错偶极子和界面裂纹的弹性干涉作用.利用复变函数方法,得到了该问题复势函数的封闭形式解答.求出了由位错偶极子诱导的应力场和裂纹尖端应力强度应子,分析了偶极子的方向,偶臂和位置以及材料失配对应力强度因子的影响.推导了作用在螺型位错偶极子中心的像力和力偶矩,并讨论了界面裂纹几何条件和不同材料特征组合对位错偶极子平衡位置的影响规律.结果表明,裂纹尖端的螺型位错偶极子对应力强度因子会产生强烈的屏蔽或反屏蔽效应.同时,界面裂纹对螺型位错偶极子在材料中运动有很强的扰动作用.

INTERACTION OF A DISLOCATION DIPOLE WITH A MODE Ⅲ INTERFACE CRACK

The elastic interaction between a screw dislocation dipole and a mode III interface crack is investigated.By using the complex variable method,the closed form solutions for complex potentials are obtained when a screw dislocation dipole is located inside one media.The stress fields and the stress intensity factors at the tips of the interface crack produced by the screw dislocation dipole are given.The influence of the orientation,the dipole arm and the location of the screw dislocation dipole as well as the material mismatch on the stress intensity factors is discussed.The image force and the image torque acting on the screw dislocation dipole center are also calculated.The mechanical equilibrium position of the screw dislocation dipole is examined for various material property combinations and crack geometries.The results indicate that the shielding or anti-shielding effect on the stress intensity factor increases acutely when the dislocation dipole approaches the tip of the crack.Additionally,the perturbation influence of the interface crack on the motion of the dislocation dipole is also significant.