1996 Fiscal Year Final Research Report Summary
An improvement in the resistance ability of fatigue crack propagation in a metal
| Project/Area Number |
07650109
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | University of the Ryukyus |
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Principal Investigator |
MAKABE Chobin Faculty of Engineering, University of the Ryukyus Associate Professor, 工学部, 助教授 (70181609)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Fatigue / Crack propagation / Crack closure / Cross-section shape / Local-heated material / Machining method / Residual stress / Metal |
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| Research Abstract |
If we can detect the crack initiation and control the crack propagation, the fracture accident owing to the metal fatigue can be reduced. Therefore, an improvement in the resistance ability of fatigue crack propagation in a metal was studied. For this purpose, the materials were machined and heat-treated by some method.
One of these specimen has a groove which is cut in the loading direction. In this specimen the fatigue crack propagation was investigated when the material has a cross-section of complicated shape. The nondimensional depth of groove to the specimen thickness b/t was chosen three values, that is, b/t=0.125,0.45,0.65. The delay of crack propagation was observed in the case of b/t=0.65. Therefore, the resistance ability of fatigue crack propagation of a material can be improved, if the material was machined in a special shape.
The crack propagation behavior of a local-heated specimen was investigated. This specimen was used for the substitution of a composite material. When the local-heated zone was located in front of the crack tip, the crack propagation rate was decelerated.
From those results, it is found that a material can be improved in the resistance of the fatigue crack propagation, if the material is machined or heat-treated by a special technique. Also, it is expected that composite material can be designed for the purpose that the fatigue crack propagation rate is decelerated.
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