A multiscale analysis for crack propagation in metallographic structure to realize mechanism of material strength

2021 Fiscal Year Final Research Report

• Project/Area Number: 17K17627
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Materials/Mechanics of materials; Computational science
• Research Institution: University of Tsukuba
• Principal Investigator: Shintaku Yuichi 筑波大学, システム情報系, 助教 (80780064)
• Project Period (FY): 2017-04-01 – 2022-03-31
• Keywords: マルチスケール解析 / 破壊力学 / 損傷力学 / 結晶塑性 / 異方性損傷モデル / 脆性破壊 / き裂進展 / 計算力学

Outline of Final Research Achievements

In this study, a multiscale analysis for crack propagation in metallographic structure is developed by combination between the proposed anisotropic damage constitutive law and new homogenization method to realize mechanism of material strength. The proposed anisotropic damage constitutive law enables us to represent crystallographic slip and cleavage fracture in brittle fracture. Also, we propose the new homogenization method that does not explicitly assume boundary conditions for microstructures with random or localized inhomogeneities. Specifically, instead of the periodic constraint condition on the fluctuation displacement, a condition is imposed such that the domain integral of the gradient is zero, which preserves the definition of macroscopic strain in the homogenization theory. The capability of our developed multiscale analysis is demonstrated throughout prediction of material strength of the polycrystalline aggregate and its dispersion.

Free Research Field

計算力学

Academic Significance and Societal Importance of the Research Achievements

材料の破壊現象における長年の課題として、同一の材料でも部材ごとに異なる強度を示すバラつきの問題が知られている。しかしながら、既存の理論体系では金属をマクロ的に均一な材料とみなすために材料強度のバラつきの問題を理論的に解決できず、材料組織設計に耐えうるものとはなっていない。そこで本研究では、ミクロ構造におけるき裂進展を微視的メカニズムに基づいてシミュレートし、無用な近似を使うことなく忠実にマクロ構造へ接続する新たなマルチスケール解析手法を構築する。これにより、ミクロ構造の不均一性に起因する脆性破壊における強度発現のメカニズムを再現し、そのバラつきを予測可能とする。