直Volterra位错芯屈服区构型

CONFIGURATION OF YIELD ZONE FOR STRAIGHT VOLTERRA DISLOCATION CORE

根据各向同性连续介质中的弹性应力场和Mises屈服准则,计算出直Volterra位错芯屈服区的二维几何构型.结果表明:在无限弹性体中,直刃型Volterra位错芯屈服区呈哑铃状.且在滑移面上屈服半宽度最大reg=5.9b（b为Burgers矢量模）,攀移面上屈服半宽度最小rec=1.4b;直螺型Volterra位错芯屈服区为圆形,屈服半径,rs=4.1b.在半无限弹性体中,受自由表面镜像位错的作用,直螺型位错芯屈服中心向表面偏移,屈服区形态依赖于直螺型位错线与自由表面的间距.

According to the elastic stress field in the isotropic medium and Mises yield rule, the configuration of yield zone for the straight Volterra dislocation core was calculated. The results show that in infinite elastic medium, the size of yield zone for a straight dislocation is directivity proportional to its Burgers vector b and shear modulus mu, but inversely to the yield strength sigma(s). The configuration of yield zone for a straight screw Volterra dislocation core is circular and yield radius r(s) is 4.1b and that for a straight edge Volterra dislocation core is a dumbbell-like, the maximum half width of yield zone on the sliding plane is 5.9b and minimum half width is 1.4b. In half infinite elastic medium, the yield zone of straight screw dislocation core would shift toward the free surface due to the effect of image force. The configuration of yield zone is dependent on the distance, 1, between the screw dislocation line and free surface parallel to it. When l > 2r(s), the configuration of yield zone for a screw dislocation core is egg-shaped, l = 2r(s), dropping-water like, and l < 2r(s), the yield zone would extend on the free surface.