Monday, July 15, 2013

1307.3377 (Péter Dusán Ispánovity et al.)

Avalanches in 2D Dislocation Systems: Plastic Yielding is not Depinning    [PDF]

Péter Dusán Ispánovity, Lasse Laurson, Michael Zaiser, István Groma, Stefano Zapperi, Mikko J. Alava
We study the properties of strain bursts (dislocation avalanches) occurring in two-dimensional discrete dislocation dynamics models under quasistatic stress-controlled loading. Contrary to previous suggestions, the avalanche statistics differs fundamentally from predictions obtained for the depinning of elastic manifolds in quenched random media. Instead, we find an exponent \tau =1 of the power-law distribution of slip or released energy, with a cut-off that increases exponentially with the applied stress and diverges with system size at all stresses. These observations demonstrate that the avalanche dynamics of 2D dislocation systems is scale-free at every applied stress and, therefore, can not be envisaged in terms of critical behavior associated with a depinning transition.
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