| Project/Area Number |
01550054
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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 |
機械材料工学
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| Research Institution | Chiba University |
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Principal Investigator |
HAGA Osamu Chiba University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (10009277)
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| Co-Investigator(Kenkyū-buntansha) |
KOYAMA Hideo Chiba University, Faculty of engineering, Associate Professor, 工学部, 助教授 (60114279)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1990: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1989: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Composite material / Aluminum / CFRP / Hybrid material / Residual stress / アルミニュウム |
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| Research Abstract |
This composite material has been built up from many thin aluminum alloy and unidirectional CFRP layers. The curing is performed at a temperature of 120ﾟC. As a result of the different thermal expansion coefficients of aluminum alloy and CFRP layer residual thermal stresses are present after cooling down from the curing temperature to room temperature. Tensile residual stress occurs in the aluminum alloy sheet, and as a consequence, the residual stress in the CFRP layer is compressed. Two methods were used to control the residual thermal stress. One is to cure the composite under tensile forec applied to the CFRP layers only and the second is to applied a strain to the composite plate, made normally, until some small plastic strain is produced in the aluminum layer. Due to the first method, because of the weakness of non-cured CFRP prepreg sheets, the controlling limit of residual stress was about 0 MPa. So the residual stress in the aluminum alloy could not be obtained in compression.
… More
The second method was very simple and the residual stresses could be controlled more precisely than in the first method. The tensile yield stress of the composites plate of which residual stress es were controlled in lower level increased more than that of plate not controlled. However, the ultimate strain and the inter laminar shear strength decreased due to the operation of the residual stress control. Some acoustic emission inspections showed that match interfacial failure produced between aluminum alloy and CFRP layers under the operation of the second method. It was estimated that this was the factor causing the decrease in the inter laminar shear strength. The effects of residual stress control particularly appeared on the fatigue properties. Velocity of a cluck propagation decreased with decreasing of the residual stress of aluminum layer. Under the conditions of low average stress and narrow stress amplitude, the cluck propagation of the test specimen of which residual stress of aluminum layer was changed into compression stopped completely. Fatigue resistance of hybrrid plates, even if they were not controlled, was enormously greater than that of monolithic aluminun alloy plate. By this fact we could understand that the CFRP layers disturb the cluck propagation on the aluminum layers in the hybrid plate. Less
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