Occurrence and motion of dislocation from Mode II crack tip in bcc crystal
Nakatani Akihiro; Kitagawa Hiroshi; Nakatani Keiko
Abstract:The atomic scale deformation near the crack tip field in bcc crystal under anti twining in plane shear (Mode II) loading is analyzed by means of molecular dynamics (MD). The appearance and movement of dislocations on (112) plane whose Burgers' vector b = [111] /2 are observed. The critical stress intensity factor (KIIcr) obtained from the analysis of the edge dislocation observed at the crack tip does not depend on the condition of analysis, and agrees well with the Rice's standard value of KIIcr. The experimental expression for the relationship between the velocity of dislocation vd and t, which was proposed in our previous report, is applied to the numerical calculation of the motion of dislocation in stress field which is evaluated by considering the interaction between crack and dislocation with linear elasticity. The results of the numerical calculation agree with those of MD simulation. Key Words:computational mechanics, molecular dynamics, dislocation, ductile fracture, crack stress intensity factor