ON THE DYNAMIC INTERACTION BETWEEN MOVING DISLOCATIONS

The dynamic interaction between dislocations moving on parallel slip p lanes is considered. It is shown that the average interaction stress c an be expressed in terms of second-order gradients of the mobile dislo cation density and the logarithm of dislocation velocity. The derivati on may be used as a basis for the justification of gradient-dependent plasticity models which have recently become popular in the literature on the mechanics of materials. It may also be viewed as providing add itional physical insight into earlier models of gradient dislocation d ynamics. Some implications of the derived gradient terms for the spati al organization and propagation of slip after yield are discussed.