Research on rational stress calculation method for structural hot-spot stress based fatigue evaluation

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04233
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22020:Structure engineering and earthquake engineering-related
• Research Institution: Nagoya University
• Principal Investigator: Hanji Takeshi 名古屋大学, 工学研究科, 准教授 (80452209)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: ホットスポット応力 / 溶接継手 / 疲労強度評価 / 維持管理

Outline of Final Research Achievements

In this study, we focused on the hot spot stress method as a fatigue strength evaluation method for welded joints. First, regarding its applicability to fatigue cracks originating from a weld toe on plate edge, it was shown that although there is considerable scatter in the test results when using the IIW-3 point method (4-8-12 mm method), a safe-side evaluation is possible with JSSC-E class. Additionally, concerning the effect of out-of-plane bending, we determined the membrane stress component and the bending stress component from the stresses on the front and back surfaces of the plate at the reference points, and calculated separately the membrane and bending stress components of the hot spot stress. By correcting the bending stress component with the JSSC method, we demonstrated the possibility of reducing the scatter in the hot spot stress range caused by the inclusion of bending.

Free Research Field

鋼構造学

Academic Significance and Societal Importance of the Research Achievements

ホットスポット応力自体は古くからある概念ではあるが，その算出法における板厚や面外曲げの影響，板側面からの疲労き裂に対する適用性などが明確になれば，ホットスポット応力法の精緻化につながり，さらには，設計基準類の改訂・整備のための貴重な資料となる．ホットスポット応力法がより使いやすいものとなり，公称応力法とならぶ疲労評価法として普及すれば，設計および維持管理段階で実挙動に基づく合理的な疲労評価が可能となる．本研究により，上記課題に対する一定の知見を示すことができ，得られた成果は社会的・学術的にみて貴重なものである．