| Project/Area Number |
60550399
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Building structures/materials
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| Research Institution | Kumamoto University |
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Principal Investigator |
MITSUI Yoshiyuki Kumamoto University, Faculty of Engineering, Professor, 工学部, 教授 (70040384)
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| Co-Investigator(Kenkyū-buntansha) |
KUROBANE Yoshiaki Kumamoto University, Faculty of Engineering, Professor, 工学部, 教授 (30040372)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1985: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Fillet-Welded Joints / Bending Fatigue Tests / Fatigue Crack Growth / Residual Stress / Stress-Relieved / 板厚の寸法効果 |
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| Research Abstract |
In order to study the effects of plate thickness on fatigue crack growth behaviors along weld toe lines, fatigue tests of plate specimens with fillet-welded gussets were performed under load-controlled pure bendings. The thickness of the through plate was selected to be 12, 25 and 38mm of JIS SM50A grade steel. The specimens with 12 and 25mm thick plate were machined to each size of thickness after or before welding. The obtained results are as follows:
(1) The elastic stress concentration factor Kt due to weld toe geometries increases as the plate thickness increases.
(2) The equation of fatigue crack growth rates for -1 to 0.5 of stress ratio is proposed.
(3) In as-welded specimens, surface cracks along the weld toe lines grow to the transverse direction simultaneously with the vertical direction. However, in stress-relieved specimens, cracks grow rapidly to the transverse direction and gradually to the vertical direction.
(4) Fatigue crack initiation life Nc decreases as the plate thickness increases. The effects of Stress-relieved on improving Nc are not significant.
(5) Fatigue life Nf of as-welded specimens decreases largely as the plate thickness increases. However, in stress-relieved specimens, the effects of the plate thickness on Nf are not significant.
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