Avalanches and scaling in plastic deformation
- Marisol
Plastic deformation of crystalline materials is a complex non-homogeneous process characterized by avalanches in the motion of dislocations. We study the evolution of dislocations loops using an analytically solvable phase-field model of dislocations for ductile single crystals during monotonic loading. We present simulations of dislocations under slow external loading that generate scale-free avalanches and power-law behavior that are characteristics of self organized criticality. The distribution of dislocation loop sizes is given by P(A) {approx} A{sup -{sigma}}, with {sigma} = 1.8 {+-} 0.1. The power law exponent is in agreement with those found in acoustic emission measurements on stressed ice single crystals. In addition to the jerky character of dislocation motion, this model also predicts a range of macroscopic behaviors in agreement with observation, including hardening and dislocation multiplication with monotonic loading and a maximum in the acoustic emission signal at the onset of yielding. At sufficient large stress, the hardening rate drops and the stress-strain curve saturates. At the same time the acoustic emission as well as the dislocation production decreases in agreement with experimental observation.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 977511
- Report Number(s):
- LA-UR-04-1803; TRN: US201009%%809
- Resource Relation:
- Journal Volume: 93; Journal Issue: 12; Conference: Submitted to: Second international conference on multiscale materials modeling, October 2004, Los Angeles, CA
- Country of Publication:
- United States
- Language:
- English
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