A dislocation density based constitutive model for the face centered cubic crystal structure was implemented into a crystal-plasticity finite element framework and extended to consider the mechanical interaction between mobile dislocations and grain boundaries. The approach to model the grain boundary resistance against slip was based upon the introduction of an additional activation energy into the rate equation for mobile dislocations in the vicinity of internal interfaces. This energy barrier was derived from the assumption of thermally activated dislocation penetration events through grain boundaries. The model takes full account of the geometry of the grain boundaries and of the Schmid factors of the critically stressed incoming and outgoing slip systems. Attention was focused here on the influence of the one remaining model parameter which could be used to scale the obstacle strength of the grain boundary.

Studying the Effect of Grain Boundaries in Dislocation Density Based Crystal-Plasticity Finite Element Simulations. A.Ma, F.Roters, D.Raabe: International Journal of Solids and Structures, 2006, 43[24], 7287-303