Can Dislocations be Accelerated through the Sonic Barrier?

It has been conjectured, on the basis of the Atkinson-Cabrera solution for the steady motion of a dislocation in a modified Frenkel-Kontorova model, that dislocations can be accelerated from subsonic to supersonic velocities. Computer-simulation results are presented to show that the regular dislocation motion assumed in the Atkinson-Cabrera solution breaks down, and the solution ceases to be valid before the sound velocity is reached.