FTMP場の理論に基づく粒内不均質場発展に伴うバウシンガ効果の多結晶粒スケールへの影響に関する研究

抄録

This paper attempts to quantitatively evaluate Bauschinger effect based on Field Theory of Multiscale Plasticity (FTMP). In FTMP, deformation-induced structures emerge spontaneously during the course of elasto-plastic deformation in a context-dependent manner, where “context-dependent” means that it tends to sensitively capture various pieces of information associated with the crystallography, fluctuating stress/strain fields and prescribed boundary conditions including imperfections. This study deals with FCC single crystal models and dual phase models with 23 grains under tensions followed by load reversal. The 23-grained dual phase models contain hard grains with 50% volume fraction with various strength ratios. What has been revealed first is the critical roles of the dynamic interplay among local/global instabilities caused or controlled by the orientation-dependent substructure evolutions, in terms of strain energy storage and/or release. By looking into the interrelationships among the incompatibility tensor, strain energy fluctuation and the duality coefficient at maximum tension measured right before load reversal, based on the Flow-Evolutionary hypothesis, the transient softening measured by Bauschinger strain is demonstrated to be evaluated quantitatively by the reciprocal of the duality coefficient, capturing governing mechanisms of the inhomogeneity-induced Bauschinger effect.