1991 Fiscal Year Final Research Report Summary
Fatigue Crack Growth Behaviors at The toes of Welded Joints under Programme Loads.
| Project/Area Number |
02650404
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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 Univ., Dep. of Architecture, Professor, 工学部, 教授 (70040384)
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| Co-Investigator(Kenkyū-buntansha) |
HARADA Katsumi Ariake Technical College, Dep. of Architecture, Professor, 建築学科, 教授 (50044342)
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| Project Period (FY) |
1990 – 1991
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| Keywords | fillet-welded joints / toe of weld / program fatigue test / pure bending load / fatigue crack growth / fatigue crack initiation life / fatigue failure life / cumulative damage |
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| Research Abstract |
In order to study into fatigue crack growth behaviors along weld toe lines under service loads, fatigue tests of plate specimens with fillet-welded gussets were performed under constant and program pure bending loads. The main plate of the specimens was 16mm thick plate of JIS SM400A grade steel. The type of applied load cycle was load-controlled pure bending. Stress ratio (R) was selected to be 0.0 (repeated load) and -1 (alternating load). Types of program load cycle were 2 and 3 steps-block loadings.
The obtained results are as follows :
1. Fatigue cracks along the weld toes in the alternating test specimens grow rapidly to both the transverse and vertical direction as compared with those in the repeated test specimens. The effects of number of the steps and size of the block on the crack growth behaviors are not observed.
2. Fatigue crack initiation life Nc and fatigue failure life Nf in the alternating test specimens are shorter than those in the repeated test specimens. The test data for Nf fall on the S-N curve of the constant load test by using equivalent stress range obtained by applying the linear cumulative fatigue rule.
3. Cumulative damage factor D for Nf evaluated by Palmgren-Miner rule are approximately 1.0. On the other hand D for Nc vary between 0.3 and 1.1.
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Research Products
(4 results)
