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Homogeneous nucleation of dislocations as bifurcations in a periodized discrete elasticity model

I. Plans1, A. Carpio2 and L. L. Bonilla1

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A novel analysis of homogeneous nucleation of dislocations in sheared two-dimensional crystals described by periodized-discrete-elasticity models is presented. When the crystal is sheared beyond a critical strain F=Fc, the strained dislocation-free state becomes unstable via a subcritical pitchfork bifurcation. Selecting a fixed final applied strain Ff >Fc, different simultaneously stable stationary configurations containing two or four edge dislocations may be reached by setting F=Fft/tr during different time intervals tr. At a characteristic time after tr, one or two dipoles are nucleated, split, and the resulting two edge dislocations move in opposite directions to the sample boundary. Numerical continuation shows how configurations with different numbers of edge dislocation pairs emerge as bifurcations from the dislocation-free state.


PACS

05.45.-a Nonlinear dynamics and nonlinear dynamical systems

61.72.Bb Theories and models of crystal defects

82.40.Bj Oscillations, chaos, and bifurcations

Subjects

Condensed matter: structural, mechanical & thermal

Statistical physics and nonlinear systems

Chemical physics and physical chemistry

Dates

Issue 3 (February 2008)

Received 18 October 2007, accepted for publication 23 November 2007

Published 14 December 2007



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