2002 Fiscal Year Final Research Report Summary
Study on development of fatigue life prediction system based on neutron strain scanning method
| Project/Area Number |
12555023
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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 | 展開研究 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | Nagoya University |
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Principal Investigator |
TANAKA Keisuke Nagoya Univ., Grad.School of Eng., Professor, 工学研究科, 教授 (80026244)
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| Co-Investigator(Kenkyū-buntansha) |
MORII Yukio JAERI, Adv.Sci.Res Center, Researcher, 先端基礎研究センター, 研究員
AKINIWA Yoshiaki Nagoya Univ., Grad.School of Eng., Assoc.Professor, 工学研究科, 助教授 (00212431)
HAYASHI Makoto Hitachi Co.Ltd., Div.Atomic Energy, Researcher, 原子力事業部, 研究員
KIMURA Hidehiko Nagoya Univ., Grad.School of Eng., Res.Assciate, 工学研究科, 助手 (60345923)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Neutron diffraction / Residual stress / Fatigue / X-ray stress measurement / Composite materials / Crack / Diffraction elastic constant / Synchrotron radiation |
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| Research Abstract |
1. The loading stress in sample specimens was measured by the neutron diffraction method to check the accuracy of the measured stress value. The diffraction elastic constants can be estimated from the single crystal elastic constants by combining Kroner model with the self-consistent model. In the plastic range, plastic anisotropy should be taken into account for stress determination. A new method is proposed to determine the strain-free lattice spacing.
2. The microstress and macrostress can be evaluated separately by the neutron method. Several applications of the method to composites showed those stresses which agreed with the theoretical predictions baed on Esheby inclusion mechanics.
3. A scanning method was proved to be useful to measure the distribution of strain within the bulk samples. Because of a low intensity of neutron sources, the minimum volume that can be measured by the neutron method was 2mm cube. The improvement of the special resolution is necessary to determine steep stress gradients.
4. The neutron diffraction system developed by the present method was successfully applied to measure the residual stress distributions in several engineering materials and components.
5. To measure the stress very near the surface, "the surface effect" will cause the error of the measured stress. The small divergence of the beam is effective to reduce this effect.
6. High energy X-rays from synchrotron radiation will be a useful method to measure the stress distribution near the surface. A combination of the neutron method with high-energy and laboratory X-rays will be a promising new toll for nondestructive measurements of residual stress distributions.
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