Complexity in dislocation dynamics: model

We propose a numerical model to study the viscoplastic deformation of ice s ingle crystals. We consider long-range elastic interactions among dislocati ons, the possibility of mutual annihilation, and a multiplication mechanism representing the activation of Frank-Read sources due to dislocation pinni ng. The overdamped equations of motion for a collection of dislocations are integrated numerically using different externally applied stresses. Using this approach we analyze the avalanche-like rearrangements of dislocations during the dynamic evolution. We observe a power law distribution of avalan che sizes which we compare with acoustic emission experiments in ice single crystals under creep deformation. We emphasize the connections of our mode l with nonequilibrium phase transitions and critical phenomena. (C) 2001 El sevier Science B.V. All rights reserved.