2001 Volume 44 Issue 4 Pages 453-461
A computer simulation for fatigue crack growth is described. The simulation is based upon the crack-tip opening process which is induced by the emission and movement of dislocations from the crack-tip. The behavior of the dislocations is determined using the dislocation dynamics method. The basic analysis for the elastic interaction between a Mode I crack and discrete edge dislocations shows that the existence of dislocations in the vicinity of the crack-tip suppresses the emission of new dislocations. This result predicts that the shielding effect which results from the residual dislocations around a fatigue crack is an important factor affecting crack propagation rate. Further, the results of the simulation show that the temporary variation in crack propagation rate with the sharp increase or decrease in the stress intensity factor range can be caused by the change in the shielding effect of the residual dislocations which are left behind the moving crack front.