General Assessment of Fatigue Reliability of Composite Material Structures
| Project/Area Number |
63420038
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
船舶構造・建造
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KIMPARA Isao Univ. of Tokyo, Fac. Eng., Prof., 工学部, 教授 (50011101)
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| Co-Investigator(Kenkyū-buntansha) |
OHSAWA Isamu Univ. of Tokyo, Fac. Eng., Assist., 工学部, 助手 (00143389)
SUZUKI Toshio Univ. of Tokyo, Fac. Eng., Assist., 工学部, 助手 (20010895)
KAGEYAMA Kazuro Univ. of Tokyo, Fac. Eng., Assoc. Prof., 工学部, 助教授 (50214276)
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| Project Period (FY) |
1988 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥17,400,000 (Direct Cost: ¥17,400,000)
Fiscal Year 1990: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1989: ¥5,100,000 (Direct Cost: ¥5,100,000)
Fiscal Year 1988: ¥9,300,000 (Direct Cost: ¥9,300,000)
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| Keywords | Composite material structures / Fatigue reliability / Fatigue damage / S-N diagram / Stiffness reduction curve / AE method / Acousto-ultrasonic method / Evaluation of defects / SーN線図 / AE特性 / 層間き裂進展特性 / AE |
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| Research Abstract |
The three-years research program has been completed aiming at general assessment of fatigue reliability of composite material structures. The main results are summarized as follows :
1. A testing system was developed based on a servopulser with two-column loading frames installed with repeated loading fixture under variable load ratio in circulation environment chamber which can optionally be connected with AE measuring and analyzing instruments in order to make a systematic assessment of fatigue damage of composite material structures.
2. A systematic three-point flexural fatigue test was carried out on glass, aramid and glass/aramid hybrid FRP laminates for marine use in air and in water. The standard fatigue design data was obtained and the damage fatigue mechanism was characterized in terms of S-N diagrams and stiffness reduction curves.
3. The acousto-ultrasonic method and the AE method were applied to evaluate the effects of progressive fatigue damage. It was shown that the fatigue damage was successfully characterized in terms of apparent change in attenuation of through-thickness ultrasonic wave propagation and some AE parameters such as hits and amplitudes.
4. An attempt was made to characterize the AE properties of CFRP laminates containing several types of artificial defects such as void and delamination. The effect of defects on strength of CFRP laminates was examined by means of monotonous and cyclic three-point flexural loading. Some correlations between AE parameters and defects were established in terms of AE hits, amplitude and AE hits during load hold.
5. The enough data has not yet been obtained on systematic fatigue tests on standarddefect specimens and FRP joint structures in salt water. The effect of load ratio on durability of composite material structures has also not yet been clarified. The general fatigue design data including these characterizations will be presented in the near future.
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Report
(4 results)
Research Products
(6 results)
