A Study on Dislocation Movement and Stress Field near Fatigue Crack Tip by Discrete Dislocation Dynamics

摘要

The 2-dimensional Discrete Dislocation Dynamics (DDD) analysis was carried out in order to elucidate the stress distribution and dislocation behavior around stationary and growing fatigue crack tips. The forward slips during loading and the reverse slips during unloading were emerged near the crack tip. The high compressive stress, which caused the reverse slips during unloading, was induced by many positive dislocations piled up remote from the crack tip. The model taking into account the crack growth was suggested in order to investigate the effect of the dislocations left in the crack wake as a result of crack growth on the stress distribution and the dislocation behavior near the crack tip. In the growing fatigue crack, the compressive stress was produced by the reaction forces of the dislocations left in the crack wake in addition to the piled up positive dislocations. And it was confirmed that the cyclic plastic deformation around the fatigue crack tip was well simulated by means of DDD.