2005 Fiscal Year Final Research Report Summary
Effects of Cyclic Fatigue on Fracture Behavior at Practical Loading rates in Carbon Composites
| Project/Area Number |
15360356
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Composite materials/Physical properties
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
TANABE Yasuhiro Tokyo Institute of Technology, Materials and Structures Laboratory, Associate Professor, 応用セラミックス研究所, 助教授 (70163607)
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| Co-Investigator(Kenkyū-buntansha) |
YASUDA Eiichi Tokyo Institute of Technology, Materials and Structures Laboratory, Professor, 応用セラミックス研究所, 教授 (70016830)
AKATSU Takashi Tokyo Institute of Technology, Materials and Structures Laboratory, Assistant Professor, 応用セラミックス研究所, 講師 (40231807)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Carbon Composites / Strain Rates / Loading Rates / Fatigue |
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| Research Abstract |
In Carbon fiber reinforced carbon composites (C/C composites), fatigue conditions for bending and shear modes are much different each other. In bending, fatigues are accelerated with increasing stress ratios, but in shear they are accelerated with decreasing the ratios. In some composites, fatigues are accelerated in water or in high humidity. In carbon fiber reinforced epoxy resin composites (CFRP), fracture behavior can be controlled by changing hardening agent even at high loading rates. However, the stress and/or strain detected by gauges are not much different among the different CFRPs with different hardening agents. Therefore, the changes in the behavior seem to be originated from localized deformation. The effects of interfaces on the reflection of stress waves and on the initiation of damages are evaluated by using in situ high-speed photographs : The interfaces act as a damage sources in certain cases. In C/C composites, fatigue surely affects the behavior of crack behaviors : crack-path changes before and after fatigue tests. The changes in fracture energy are small at the loading rates of Charpy tests by changing the matrix resins, but interface adhesion affects the absorption in all loading rates.
The above experimental results indicate that controlling of interfacial bonding is important in an off-axial loading of fatigue, and that the bonding should be controlled depending on the loading rates. The material parameters to be controlled are demonstrated through the experiments.
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