2023 Fiscal Year Final Research Report
Development of assessment technology for welding process conditions maximizing fatigue performance of welded structures
| Project/Area Number |
21H01545
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 24020:Marine engineering-related
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| Research Institution | Osaka University |
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Principal Investigator |
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | 疲労 / 弾塑性 / 亀裂 / FEM |
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| Outline of Final Research Achievements |
In order to evaluate the influence of the local elastoplastic response near the fatigue crack initiation location on the fatigue life of the welded joint, we used a simulated HAZ material targeting the SM490A base metal and the welded joint near the fatigue crack initiation location. We conducted a fatigue test and proposed a cyclic material response simulation that can reproduce the experimental results of the elastoplastic response and a fatigue crack initiation and propagation life evaluation formula. Next, this was applied to a non-load-transferring cruciform welded joint, and the results were discussed through fatigue life evaluation and comparison with experimental results. We have developed a material model that can reproduce elastic-plastic responses including macroscopic elastic states with high accuracy, and we have made it possible to apply fatigue crack initiation and growth evaluation methods that depend on joining conditions to welded joints.
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| Free Research Field |
応用力学
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| Academic Significance and Societal Importance of the Research Achievements |
溶接部を起点とする疲労損傷事例が多数報告され、その要因として、溶接部と構造的な不連続部が一致する、かつ溶接余盛や時に欠陥も存在するため高応力となる、溶接入熱による母材と溶接金属の希釈およびその後の冷却速度など、溶接プロセス条件に依存して不均一な材料組織/形状/強度分布と残留応力/残留変形が生じる、さらに、大型溶接構造物が実際に経験する応力や変形状態は、多軸/非比例/変動履歴となるため、実験的検討には限界があることなどが挙げられる。つまり、溶接プロセス条件に依存する疲労性能評価の高度化には、上記影響因子を適切に考慮可能な数値シミュレーション技術開発と実設計および施工への展開が重要である。
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