A hybrid multiscale computational framework of crystal plasticity at submicron scales

Mechanical behavior for crystals at submicron-to-nanometer scales shows many atypical plastic phenomena. In this paper, a new hybrid multiscale simulation method named DD-FEM is developed by coupling the 3D discrete dislocation dynamics (DDD) simulation with the finite element method (FEM) under elasto-viscoplasticity continuum model. In this methodology, the discrete dislocation plasticity in a finite crystal is solved under a completed continuum mechanics framework. Our approach is competent at dealing with the large and non-linear deformation by communicating deformation information between DDD and FEM. As an application, the deformation of micropillar under uniaxial compression has been predicted. Our results show that the source-truncation hardening and mobile dislocation exhaustion hardening are the main mechanisms for flow intermittency, and stress heterogeneity plays a key role in the observed strain hardening. The effects of contact boundary condition between the indenter and the upper surface of the specimen, as well as the taper of the pillar are also investigated.