Shielding Effect of Emitted Dislocations on Fatigue Crack Propagation

Abstract

This study is conducted to clarify the influence that the dislocations left over around the fatigue crack have on the propagation rate through the computer simulation of the dislocation dynamics. The computer simulation is based on the equation concerning the elastic interaction of a semi-infinite crack with edge dislocations. The result of the basic analysis shows that the exisitence of dislocations near the crack-tip suppress the emission of new dislocations. This predicts that the shielding effect owing to the dislocations is one of the important factors which affect the propagation rate of the fatigue crack. Furthermore, the results of the computer simulation show that the transient fatigue crack propagation with the sudden change of the stress intensity factor amplitude can be qualitatively understood from the viewpoint of the change of the shielding effect which is induced by the dislocations left over around the crack.