螺型位错偶极子与圆形夹杂界面裂纹的弹性干涉

A SCREW DISLOCATION DIPOLE INTERACTING WITH A CIRCULAR-ARC INTERFACE CRACK

  • 摘要: 该文研究了螺型位错偶极子和圆形夹杂界面裂纹的弹性干涉作用。利用复变函数方法,得到了该问题的复势函数以及应力场的封闭形式解答。求出了裂纹尖端的应力强度因子以及作用在螺型位错偶极子中心的像力和像力偶矩,并分析了位错偶极子对应力强度因子的影响及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。研究结果表明:位错偶极子对应力强度因子具有很强的屏蔽或反屏蔽效应;硬夹杂排斥位错偶极子,而裂纹吸引位错偶极子,在一定条件下,位错偶极子在裂纹附近出现一个平衡位置;当裂纹的长度和材料剪切模量比达到临界值时,可以改变偶极子和界面之间的干涉机理。同时,裂纹长度对位错偶极子中心像力偶矩也有很大的影响。

     

    Abstract: This paper investigates the problem of the elastic interaction between a screw dislocation dipole and a circular interface crack. Using the complex variable method, the closed form solutions of complex potentials and the stress fields are obtained, which is produced by the screw dislocation dipole locating in one media. The stress intensity factor at the tip of the crack, the image force and the image torque acting on the screw dislocation dipole center are also calculated. The influence of screw dislocation dipole upon stress intensity factor and the equilibrium position of the screw dislocation dipole are examined for various material property combinations and interfacial crack geometries. The results show that: 1) The screw dislocation dipole has significant shielding or anti-shielding effect on the stress intensity factor; 2) Different with the interface crack which attracts the screw dislocation dipole, the hard inhomogeneity always repels it, and the screw dislocation dipole reaches equilibrium in the neighbor of crack under some combination of them; 3) If the length of the crack or the ratio of two shear moduli reaches a critical value, the presence of the crack can change the interaction mechanism between the dipole and the interface. In addition, the influence of the crack length on the equilibrium of the dipole is significant.

     

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