Gérald Franz

A Multiscale Model Based On Intragranular Microstructure — Prediction Of Dislocation Patterns At The Microscopic Scale

A large strain elastic-plastic single crystal constitutive law, based on dislocation annihilation and storage, is implemented in a new self-consistent scheme, leading to a multiscale model which achieves, for each grain, the calculation of plastic slip activity, with help of regularized formulation drawn from visco-plasticity, and dislocation microstructure evolution. This paper focuses on the relationship between the deformation history of a BCC grain and induced microstructure during monotonic and two-stage strain paths.

Effect of microstructural and physical mechanisms on mechanical properties of single-phase steels

The current work aims to investigate the impact of microstructural and physical mechanisms on the macroscopic behavior and ductility of single-phase steels. For this purpose, an advanced multiscale model, accounting for intragranular microstructure development and evolution, is coupled with a formability limit criterion based on bifurcation theory. The overall response for polycrystalline aggregates is obtained from a large-strain elasticplastic single crystal constitutive law, using a self-consistent scale-transition scheme. This approach takes into account essential microstructural aspects such as initial and induced textures, dislocation densities, softening mechanisms so that the behavior during complex loading paths is properly described. Focus will be placed here on the relationship between intragranular microstructure of B.C.C. steels and their ductility. The model allows interesting qualitative study in terms of formability limits for various dislocation networks, during monotonic loading tests applied to single-phase steels, with the aim of helping in the design of new materials.

A Multiscale Model Based On Intragranular Microstructure: Influence Of Grain-Scale Substructure On Macroscopic Behaviour Of An IF-Steel During Complex Load Paths

A microstructural model, based on Peeters’ works, is implemented into a large strain self‐consistent scheme, leading to the multiscale model which achieves, for each grain, the calculation of slip activity, with help of regularized formulation drawn from the visco‐plasticity framework, and the dislocation microstructure evolution. This paper focuses on the relationship between macroscopic hardening/softening effects and induced microstructure during monotonic and two‐stage strain paths.