Cosserat crystal plasticity with dislocation driven grain boundary migration

International audience; This paper discusses a coupled mechanics-phase field model that can predict microstructure evolution in metallic polycrystals and in particular evolution of lattice orientation due to either deformation or grain boundary migration. The modeling framework relies on the link between lattice curvature and geometrically necessary dislocations and connects a micropolar or Cosserat theory with an orientation phase field model. Some focus is placed on the underlying theory and in particular the theory of disloca-tions within a continuum single crystal plasticity setting. The model is finally applied to the triple junction problem for which there is an analytic solution if the grain boundary energies are known. The attention is drawn on the evolution of skew-symmetric stresses inside the grain boundary during migration.