1995 Fiscal Year Final Research Report Summary
Residual Stresses and Theomomechanical Behavior of Fiber-Reinforced Aluminum Composites
| Project/Area Number |
06650123
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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 |
Materials/Mechanics of materials
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| Research Institution | Nihama National College of Technology |
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Principal Investigator |
IKEUCHI Yasukazu Niihama National College of Technology, Materials Science and Engineering, Professor, 材料工学科, 教授 (20044092)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Fiber-reinforced aluminum / X-ray stress measurement / Thermal residual stress / Thermal expansion / Alumina fiber / SiC fiber |
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| Research Abstract |
When a fiber-reinforced metal matrix composite is cooled down to room temperature from the fabrication or annealing temperature, residual stresses are induced in the composite because of the thermal expansion mismatch between matrix and fiber. An X-ray diffraction technique was used to measure thermal residual stresses in the matrix of two different composite systems, the first being pure aluminum or an Al-5%Cu alloy reinforced with 17-mum small diameter gamma-Al_2O_3 fibers and the second being a 6061Al alloy reinforced with 140-mum large diameter SiC_<CVD> fibers.
The triaxial state of the matrix thermal residual stress in each composite was determined. In the matrix of each annealed composite a tensile residual stress state was observed. On the measurement after cooling the annealed composite to liquid nitrogen temperature, the matrix showed a compressive stress state in each composite. In both of the matrix stress states, the longitudinal residual stress parallel to the fibers was the maximum principal stress. In the case of the composites with small diameter fibers, the stress measured normally to the surface was found to be about a half of the transverse residual stress. This can be due to the relaxation of the component of residual stress in the matrix near the surface layr.
It was confirmed that the thermal residual stress as well as the composite length depended upon the thermal history of the composite. Dimensional stability of a composite should be evaluated on the basis of the thermal residual stresses in the composite. The in-situ X-ray technique was found to be useful for deeper understanding the behavior of the thermally induced residual stresses in the composite.
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