2005 Fiscal Year Final Research Report Summary
Long-term Durability of GFRP under Corrosive Environment
| Project/Area Number |
16560081
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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 | Waseda University |
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Principal Investigator |
KAWADA Hiroyuki Waseda University, Faculty of Science and Engineering, Professor, 理工学術院, 教授 (20177702)
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| Co-Investigator(Kenkyū-buntansha) |
KOBIKI Akira Waseda university, Science and Engineering, Visiting Research associate, 理工学術院, 助手 (00373035)
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| Project Period (FY) |
2004 – 2005
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| Keywords | GFRP / Stress Corrosion Cracking / Interfacial Degradation / Fiber strength / Threshold Properties |
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| Research Abstract |
Fiber reinforced plastics (FRP) are widely used in structural applications because of their good specific stiffness and strength. In addition, corrosive resistance of the FRP is superior to conventional materials. Therefore use of the FRP under corrosive environment has been extended, such as a chemical solution storage tank. Under the environments, stress corrosion cracking is a typical problem for the conventional materials. Also, the stress corrosion cracking is a principle problem for the FRP under the corrosive environment.
Strength and stiffness depends on fiber strength, therefore strength degradation of single E-glass fiber under the water environment was investigated. The fiber strength is characterized by Weibull shape and scale parameter. As a result, the scale modulus decreased as a function of immersion time in the water. In addition, time-to-failure under constant loading in the water was measured. Distributions of the time-to-failure were predicted assuming initial defect growth on the fiber surface. The result showed that the strength degradation depended on initial strength and applied stress.
Fiber bridging of water-absorbed FRP is principle in crack propagation, therefore studied in order to estimate crack propagation resistance under water environment. The crack propagation resistance depended on the weight gain due to water absorption. Therefore the absorbed water was an essential factor to decrease the crack propagation resistance. Finally, increased resistance by the fiber bridging was predicted using bridging stress distribution that was obtained by measurements of debonding length of the bridging fiber. The propagation resistance obtained by the fiber bridging showed a good agreement with experimental results. It was found that the crack propagation under the water environment depended on the fiber/matrix interfacial properties.
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