2022 Fiscal Year Final Research Report
Creation of a Standard Method for CTOD Fracture Assessment with Repeated Prestrainn Damage Consideration for Highly Accurate Prediction of Seismic and Wave Effects
| Project/Area Number |
19H00802
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Medium-sized Section 24:Aerospace engineering, marine and maritime engineering, and related fields
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| Research Institution | The University of Tokyo |
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Principal Investigator |
Kawabata Tomoya 東京大学, 大学院工学系研究科(工学部), 教授 (50746815)
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| Co-Investigator(Kenkyū-buntansha) |
三上 欣希 大阪大学, 接合科学研究所, 教授 (40397758)
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| Project Period (FY) |
2019-04-01 – 2023-03-31
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| Keywords | 脆性亀裂発生 / CTOD / 繰り返し載荷 / 材料損傷 / 結晶塑性 |
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| Outline of Final Research Achievements |
Material damage and toughness degradation due to reverse bending/local compression treatment, which is necessary for CTOD evaluation of welded joints, were investigated both experimentally and numerically. The optimal conditions were found by weld-to-fracture simulation using Bayesian optimization, and validation tests were conducted. In-situ FE-SEM observation was also conducted to accurately determine material damage caused by positive and negative cyclic prestrain. It was found that the brittle fracture initiation characteristics after positive and negative cyclic prestrain were decreased by cyclic prestrain, and in particular, the toughness values were well correlated with the Weibull stress criterion, which takes into account the rate of change of back stress. Finally, a damage accumulation prediction equation that can be computed only from macro deformation history information was developed.
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| Free Research Field |
破壊力学、鉄鋼材料、溶接力学
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| Academic Significance and Societal Importance of the Research Achievements |
本研究では鋼構造物が予歪を受けた際の耐破壊特性変化がその予歪履歴の影響を受けることから、より精緻にメカニズムを研究し、高精度予測を行うことを目指したものである。
一つの応用は残留応力を持つ溶接継手の破壊靭性評価の際に必要な前処理方法について妥当かつ統一的な方法を提供したことであり、得られた成果はISO規格として成立し世界の技術者が使うことになる。もう一つは繰返し負荷が破壊以前に作用した場合の損傷量の定量化である。精緻なメカニズム研究を基礎に簡易式を構築したので、地震や波浪を経た後の海上・陸上構造物の継続使用可否判断などに有効となる。
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