Dislocation dynamics in the modified Frenkel-Kontorova model

Abstract
An analytical solution is presented for the atomic displacements in the steady motion of a dislocation in the modified Frenkel‐Kontorova model. The phenomenon of the breakdown of regular dislocation motion as the dislocation velocity approaches the speed of sound, found by Earmme and Weiner in the same model for γ=1/2 is seen to exist in this model for any γv the dislocation motion is unstable. Furthermore, it appears that for sufficiently low v there does not exist a steady‐state solution for γ=1/2. The final steady‐state motion achieved is found to depend both on the initial conditions and the loading history. For example it is found that in order to arrive at the no‐loss mode of motion, it is necessary to first increase the stress to a sufficiently high value, allow steady motion on the upper branch of the v−σ relation to be established, and then to decrease the stress to zero.

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