2023 Fiscal Year Final Research Report
Development of Strain Rate Controlled Highly Efficient Modified Weibull Stress Identification Test and Application to Weld Joints
| Project/Area Number |
20K04660
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 22020:Structure engineering and earthquake engineering-related
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| Research Institution | Yokohama National University |
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Principal Investigator |
Tamura Hiroshi 横浜国立大学, 大学院都市イノベーション研究院, 准教授 (10636434)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | 地震時脆性破壊 / 修正ワイブル応力 / 累積破壊確率 / シャルピー衝撃試験 |
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| Outline of Final Research Achievements |
An efficient material testing method was developed to evaluate the spatial distribution of resistance to brittle fracture from shallow initial cracks in welds by means of modified Weibull stress. Specifically, a nonlinear dynamic analysis method was first developed for Charpy impact tests. This analytical method and the application of the modified Weibull stress allowed reproduction of test results at low temperatures, and verified the applicability of the modified Weibull stress approach to strain-rate-controlled tests. Next, as a highly efficient method for identifying material parameters for the calculation of modified Weibull stress, it was attempted to develop a method for identifying material parameters from the results of impact tests on various specimens with different geometries and other parameters. As a result, specimen geometries that can re-identify material parameters for the modified Weibull stress calculation with reasonable accuracy were found analytically.
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| Free Research Field |
構造工学および地震工学関連
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| Academic Significance and Societal Importance of the Research Achievements |
鋼部材における地震時脆性破壊の多くは溶接部を起点として発生することが知られている．溶接部は熱履歴の影響で破壊じん性をはじめとした材料特性が均一となっておらず複雑に分布している．このような溶接部を起点とする地震時脆性破壊の発生を修正ワイブル応力によって予測するためには，修正ワイブル応力を計算するための各材料パラメータを溶接部の部位ごとに高密度に同定する必要がある．ひずみ速度制御型試験によりこのプロセスを効率化することができれば，溶接部を起点とする地震時脆性破壊の発生予測の実現につながるため，本研究で供試体形状を絞り込むことができたことは重要な成果であるといえる．
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