1994 Fiscal Year Final Research Report Summary
Development of estimation system for fatigue life of CFRP
| Project/Area Number |
04555029
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
材料力学
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| Research Institution | Nagoya University |
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Principal Investigator |
MURAKAMI Sumio Nagoya Univ., Engineeing, Professor, 工学部, 教授 (10023053)
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| Co-Investigator(Kenkyū-buntansha) |
TSUSHIMA Eiki Tonen Co., CF Project, Team Leader, CFプロジェクト, チームリーダー
KAWAI Masamichi Univ.of Tsukuba, Engineering, Associate Prof, 構造工学系, 助教授 (90169673)
ZAKO Masaru Osaka Univ., Engineering, Professor, 工学部, 教授 (40170831)
TANAKA Eiichi Nagoya Univ., Engineering, Associate Professor, 工学部, 助教授 (00111831)
KANAGAWA Yasushi Nagoya Univ., Engineering, Associate Professor, 工学部, 助教授 (90023481)
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| Project Period (FY) |
1992 – 1994
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| Keywords | CFRP / Fatigue life / Damage process / Inelastic deformation / Damage mechanical analysis / Multi-axial loading / Estimation of fatigue life / AE method |
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| Research Abstract |
Inelastie deformation fehavior of CFRP under quasi-statie and fatigue loading has been elucidated for three years from 1992 to 1994. Specially, internal fatigue damages of matrix crack and delamination in the fatigue process were quantitatinely estimated by means of micrography, and furthermore on-time monitoring of fatigue damage initiation and evolution by AE method was carried out successfully. From these results, it makes clean that a estimation system for fatigue life of CFRP is possibly developed with AE method. Results obtained in the research are as follows ;
1)Stress-strain relationships of [<plus-minus>45ﾟ]_4 CFRP tubular specimen were elucidated under various loading conditions. It was recognized that matrix showed similar behavior as work-hardening at the early stage of fatigue and that macroscopical buckling occured at the last stage of fatigue by delamination.
2)From detail investigation between fatigue damage and mechanical properties of CFRP,it made clean that elastic modulus and inelastic strain were useful measures for the fatigue life.
3)The continuum damage model based on the flow rule was modified to a inelastie constitutine equation in considering initiation and evolution of internal damage. And then, the modified model was applied to experimental results successfully.
4)Power spectrum of AE signal in fatigue process of CFRP was able to nondestructively identify the internal damages such as matrix crack, delamination and fiber breakage, and furthermore it could estimate the fatigue life.
5)Complex inelastic deformation behavior of CFRP in fatigue process was described by modeling in frame of the continuum damage mechanics.
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