多結晶材料の巨視的なひずみ場の数値解析による予測手法の検討

抄録

Engineering materials usually exhibit heterogeneity such as that observed in the polycrystalline structure of metals, and this heterogeneity affects the nonuniform deformation of a material. The experimental results of the nonuniform deformation of polycrystalline copper specimen with a curved gage section clarified that the randomness of the polycrystalline structure suppressed the deformation localization of the specimen. The micro- to macroscopic computational simulation based on the second-order homogenization method could not predict such a decrease in the macroscopic strain concentration in the specimens because the macroscopic structure is uniform owing to the periodic condition given to the microscopic structure. Therefore, the experimental-based inelastic nonlocal constitutive equation is attempt to be formulated by extending the elastic nonlocal constitutive equation. In the formulation process, the strain gradient caused by the microscopic heterogeneity is added to conventional elastic and plastic strain gradients, and the inelastic nonlocal constitutive equation is derived based on the J2-flow theory.