Dislocation emission from the crack tip in copper under mode II loadin
g is simulated with molecular dynamics method. After 26 partial disloc
ations are emitted and then relaxed to reach the equilibrium under the
constant displacement, the double pile-ups (including an inverse pile
-up and a pile-up) are formed. i.e., the first dislocation is piled up
before the obstruction, and the last dislocation is piled up ahead of
the crack tip. These results conform to the TEM observations.