Elastic interaction between a moving screw dislocation and a surface crack

Abstract

A moving screw dislocation near a surface crack was investigated using dislocation modeling. Motion directions parallel (x direction) and perpendicular (y direction) to the crack surface were considered. Due to the free surface, the net Burgers vector inside the crack is zero. After obtaining the dislocation distribution in the crack, we calculated the stress field in the medium. Relative to a static screw dislocation, the magnitude of σyz due to the moving screw dislocation decreases with increasing velocity Vx. Generally, the effect of dislocation shielding on fracture is reduced if the velocity Vx increases. The magnitude of the image force of the dislocation also decreases with increasing velocity Vx. The effect of velocity along the y direction on the stress intensity factor and image force has the opposite trend to that along the x direction. The present result can reduce to a moving dislocation near a semi-infinite crack and a static dislocation near a surface crack.