組織不均質を考慮した三次元延性損傷シミュレーション法 −複相組織材料の延性予測−

概要

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The effort of this study is to establish simulation method for predicting the effect of mechanical and morphological characteristics of each constituent phase of two-phase steel on two types of ductile properties that has been found to be ductile crack growth resistance controlling mechanical properties; one is critical local strain that controls shear mode ductile cracking, and the other is stress triaxiality dependent ductility. Notched micro-tensile tests for ferrite-pearlite two-phase steel exhibits that ductile failures from specimen center with dimple mode and notch-root surface with shear mode are both controlled by micro-void nucleation at softer ferrite phase near ferrite/pearlite boundary. 3D micro-structural FE-model is developed for analyzing the stress/strain localization behaviors associated with heterogeneous microstructure in strength, and ductile damage model for reproducing damage evolution up to micro-void/micro-crack formation is proposed. The 3D meso-scopic damage simulation method is applied for simulating ductile cracking behaviors of notched tensile specimens of two-phase steel. The damage evolution associated with micro-structural heterogeneity up to ductile cracking from specimen center as well as notch-root surface is well predicted.