Dynamical Behavior of Dislocations in Anisotropic Media

Publisher Website
Google Scholar
Abstract
The dynamical behavior of uniformly moving dislocations in anisotropic media is discussed for those crystal systems for which the edge and screw components can be considered separately. Expressions are obtained for the kinetic and potential energies of both edge and screw dislocations. It is found that screw dislocations behave normally at all velocities up to the limiting velocity. Edge dislocations, however, display an anomalous dynamical behavior. It appears that in general there is a range of velocities for which the shear stress on the slip plane is negative and edge dislocations of like sign attract rather than repel one another. In an isotropic material the upper limit of this velocity range is the velocity of shear sound; the lower limit is the Rayleigh wave velocity which can never be less than 0.69 the velocity of shear sound. In the anisotropic case it is possible for the limiting velocity (for a given orientation) to be less than the corresponding shear wave velocity; also the threshold velocity for the anomalous dynamical behavior can be any velocity from zero up to the shear wave velocity, depending on the elastic constants of the material and the orientation considered. An example of an edge dislocation in a hexagonal material is discussed in some detail.

This publication has 3 references indexed in Scilit: