Dislocation Dynamics Simulations (
)
Objectives
A true multiscale modeling of plasticity necessarily involves dislocation dynamics simulations to bridge various gaps between the atomistic properties of the dislocation cores, the elastic properties of dislocations, their collective behavior and the continuum approaches by solid mechanics.
Simulation tools
- The dislocation dynamics simulation "MicroMegas". This simulation code was initialy developed at the LEM, but today is a GPL simulation code developed by many users. It is quite flexible and has been adapted to several crystallographic structures, notably FCC, HC and BCC.
- The hybrid DD-FE code or the discrete-continuum model (DCM). This code is based on a coupling between the simulation codes microMegas + ZeBulon. It can treat complex stress fields (multimaterials, polycrystals, thin films) or complex types of loadings.
- A simulation for the modeling of the dynamics of parallel and infinite edge dislocations (2.5D). This simple code, based on a 2D geometry, was adjusted to reproduce as well as possible the real plastic deformation in 3D.
Recent results
- Parameter-free modeling of forest and strain hardening in FCC crystals, from elementary intersections and reactions of dislocations to the interactions between slip systems and a continuum framework.
- Detailed study of a reaction between dislocations, the collinear interaction, which has a strong impact on strain hardening properties.
- Investigations on dislocation patterning and the influence of cross-slip.
- Investigations on materials with large lattice friction: BCC, HCP Zr, olivine.
- Stress relaxation by the motion of threading dislocations in heteroepitaxial thin films.
- Study of a model composite material Al/Al2O3: local stresses and size effects.
- Similitude principle. This poorly understood phenomenon relates the size of dislocation patterns to the flow stress.
- etc ...
References and illustrations