86 research outputs found
Microstructural Comparison of the Kinematics of Discrete and Continuum Dislocations Models
The Continuum Dislocation Dynamics (CDD) theory and the Discrete Dislocation
Dynamics (DDD) method are compared based on concise mathematical formulations
of the coarse graining of discrete data. A numerical tool for converting from a
discrete to a continuum representation of a given dislocation configuration is
developed, which allows to directly compare both simulation approaches based on
continuum quantities (e.g. scalar density, geometrically necessary densities,
mean curvature). Investigating the evolution of selected dislocation
configurations within analytically given velocity fields for both DDD and CDD
reveals that CDD contains a surprising number of important microstructural
details
Avalanches, loading and finite size effects in 2D amorphous plasticity: results from a finite element model
Crystalline plasticity is strongly interlinked with dislocation mechanics and
nowadays is relatively well understood. Concepts and physical models of plastic
deformation in amorphous materials on the other hand - where the concept of
linear lattice defects is not applicable - still are lagging behind. We
introduce an eigenstrain-based finite element lattice model for simulations of
shear band formation and strain avalanches. Our model allows us to study the
influence of surfaces and finite size effects on the statistics of avalanches.
We find that even with relatively complex loading conditions and open boundary
conditions, critical exponents describing avalanche statistics are unchanged,
which validates the use of simpler scalar lattice-based models to study these
phenomena.Comment: Journal of Statistical Mechanics: Theory and Experiment, 2015, P0201
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