Computer simulation of the dynamic behaviour of dislocation groups of opposite sign emitted from a stressed source

The dynamic behaviour of straight parallel coplanar edge dislocations under constant applied stress was calculated by Rosenfield and Hahn by using an exponential relation between stress τ and velocity v:v = K exp (Bτ). However, it is more appropriate to use a power law stress-velocity relation v = Mτ^m. Thus we have previously carried out a computer simulation of the dynamic behaviour of dislocations of the same sign under a constant rate of stress application using this power law relation. In the present work we used the power law relation in a computer simulation of the dynamic behaviour under a constant rate of stress application for an equal number of positive and negative dislocations which are emitted from a stressed source and move away in opposite directions exerting forces on one another. The results are quantitatively related to those for the behaviour of dislocation groups with the same sign. It is found that the dynamic behaviour (i.e. the ratio of the position of, the effective stress on and the velocity of an individual dislocation to those of an isolated dislocation) and the number of dislocations emitted up to a given time are similar to those observed for dislocation groups of the same sign.