Atomistic simulation of dislocation void interactions under cyclic loading

The vibration and depinning of an edge dislocation in Al initially anchored at an array of voids is studied by molecular dynamics simulations. The dislocation behaviour is studied under cyclic loading in the frequency range 10-160 GHz and varying stress amplitudes. It is found that for stress amplitudes smaller than 50 MPa the vibration amplitude and phase shift are in good agreement with an atomistically informed Granato-Lucke model. At larger stresses relativistic effects cannot be neglected anymore. The depinning stress is determined under quasistatic and cyclic loading conditions. For frequencies close to the resonant frequency depinning of the dislocation is observed at significantly lower stresses than under quasistatic loading. Possible consequences of this dynamical depinning effect are discussed.