[SY-C11] FTMP-based Simulations and Evaluation of Geometrically-Necessary Boundaries (GNBs) of Dislocation
Rational as well as practically-feasible treatments of spatio-temporally distributed discrete dislocation ensembles have been a long-standing issue and still a challenging problem inevitable in completion of multiscale modeling of metallic materials. Unlike 2D cases, which cannot be simply reduced down to continuously-distributed density function-like pictures, 3D counterparts need to deal, more or less, with its configurational complexities explicitly. We have recently been tackling these based on FTMP (Field Theory of Multiscale Plasticity), focusing on continuum descriptions of dislocation aggregates. Among others, quantitative stability/instability assessments of wall structures are critically important, in the sense that they substantially dominates both the micro/macro mechanical properties of the material systems concerned. The present study targets GNBs (Geometrically Necessary Boundaries) in terms of their stability/instability criteria and some dynamic interactions with in-coming dislocations, whose details about the consisting dislocations recently have been experimentally identified and theoretically evaluated by Hong, Winther, et al. Dislocation dynamics simulations on five typical GNBs, i.e., GNBs 2, 3, 4, 7 and 8, are conducted by utilizing Zbib code and ParaDis code, and FTMP-based evaluations are performed against them. Duality diagram representations revealed a possible overall picture that governs the GNBs, i.e., all the GNBs exhibit a common tendency to converge ultimately to a single point, i.e., the ideal value for a hexagonal network-based GNB that yields the lowest energy as well as the smallest incompatibility, located in the most lower-left on the diagram.