Micro-plasticity and intermittent dislocation activity in a simplified micro structural model

Abstract

Here we present a model to study the micro-plastic regime of a stress-strain curve. In this model an explicit dislocation population represents the mobile dislocation content and an internal shear-stress field represents a mean-field description of the immobile dislocation content. The mobile dislocations are constrained to a simple dipolar mat geometry and modelled via a dislocation dynamics algorithm, whilst the shear-stress field is chosen to be a sinusoidal function of distance along the mat direction. The latter, defined by a periodic length and a shear-stress amplitude, represents a pre-existing micro-structure. These model parameters, along with the mobile dislocation density, are found to admit a diversity of micro-plastic behaviour involving intermittent plasticity in the form of a scale-free avalanche phenomenon, with an exponent for the strain burst magnitude distribution similar to those seen in experiment and more complex dislocation dynamics simulations.

30 pages, 12 figures, to appear in "Modelling and Simulation in Materials Science and Engineering"

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Cited by in corpus (6)

• Avalanches and Plastic Flow in Crystal Plasticity: An Overview
• Microstructural constitutive model for polycrystal viscoplasticity in cold and warm regimes based on continuum dislocation dynamics
• A probabilistic explanation for the size-effect in crystal plasticity
• The stress statistics of the first pop-in or intermittent plastic event in cyrstal plasticity
• Plastic strain is a mixture of avalanches and quasi-reversible deformations: Study of various sizes
• Critical stress statistics and a fold catastrophe in intermittent crystal plasticity