1989 Fiscal Year Final Research Report Summary
QUANTITATIVE MICROMECHANISTIC STRESS AND DEFORMATION ANALYSIS OF ENVIRONMENTAL CRAZES IN CRACKED POLYMERS BY USING THE SHADOW-OPTICAL-METHOD OF CAUSTICS
| Project/Area Number |
62460070
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
応用物理学一般(含航海学)
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
TAKAHASHI Kiyoshi KYUSHU UNIVERSITY, RESEARCH INSTITUTE FOR APPLIED MECHANICS, PROFESSOR, 応用力学研究所, 教授 (10010795)
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| Co-Investigator(Kenkyū-buntansha) |
SAKURADA Yasuhiro KYUSHU UNIVERSITY, RESEARCH INSTITUTE FOR APPLIED MECHANICS, RESEARCH ASSOCIATE, 応用力学研究所, 助手 (50038543)
ARAKAWA Kazuo KYUSHU UNIVERSITY, RESEARCH INSTITUTE FOR APPLIED MECHANICS, ASSOCIATE PROFESSOR, 応用力学研究所, 助教授 (00151150)
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| Project Period (FY) |
1987 – 1989
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| Keywords | CAUSTICS / CRAZING / ENVIRONMENTAL CRAZE / METHANOL CRAZE / POLYMETHYLMETHACRYLATE / POLYMER ALLOY |
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| Research Abstract |
THIS STUDY IS CONCERNED WITH EXPERIMENTAL STRESS AND DEFORMATION ANALYSIS OF A METHANOL CRAZE AHEAD OF A PMMA CRACK. THE FOLLOWINGS ARE CONCLUDED.
1. IT HAS BEEN SHOWN THAT EVALUATION OF STRESS AND DEFORMATION DISTRIBUTION AROUND THE CRAZE LAYER IS POSSIBLE BY THE USE OF CAUSTICS, I.E., SHADOW OPTICAL PATTERNS.
2. CHANGE OF THE SHADOW PATTERN OF A CRAZE-CRACK UNDER TENSION CORRESPONDS WELL TO THE CHANGE OF OUT-OF-PLANE DEFORMATION THERE.
3. IT HAS BEEN CONFIRMED THAT THERE EXISTS A STRESS CONCENTRATION AT THE CRAZE TIP, WHICH MEANS THAT USE OF THE DUGDALE MODEL HAS ITS LIMITATION FOR FRACTURE MECHANICS STUDY.
4. ELASTIC APPROXIMATION IS ALLOWABLE FOR THE CRACK TIP DEFORMATION OF A SPECIMEN REMOVED FROM METHANOL TO AIR AND DRIED. THE STRESS DISTRIBUTION OF THE CRAZE LAYER IN THIS CASE AGREED WELL WITH THE RESULT OBTAINED BY KRAMER ET AL USING THE HOLOGRAPHIC INTERFEROMETRY.
5. THE GROWTH RATE OF THE ENVIRONMENTAL CRAZE HAS A CORRELATION WITH THE DIAMETER OF THE SHADOW PATTERN.
6. THE STRESS DISTRIBUTION ALONG A CRAZE LAYER HAS BEEN MODELLED, BASED ON WHICH COMPUTER SIMULATION WAS MADE FOR PREDICTING SHADOW PATTERNS. FROM THE PATTERN FITTING WITH THE ONE OBTAINED FROM EXPERIMENTS, PARAMETERS SUCH AS STRESS AT CRACK-AND CRAZE TIPS COULD BE EVALUATED.
7. THE STRESS-OPTICAL CONSTANT WAS STUDIED AS A FUNCTION OF REFRACTIVE INDICES OF ENVIRONMENTAL LIQUIDS SURROUNDING A CRACKED PLATE UNDER TENSION. IT HAS BEEN SHOWN THAT THE OPTICAL EFFECT OF THE LIQUIDS IS NOT NEGLIGIBLE.
8. REFLECTED CAUSTIC PATTERNS HAVE BEEN OBTAINED FROM A CRACK TIP OF POLY?.IER ALLOYS, WHICH HAS DE POSSIBLE TO EVALUATE TOUGHNESS OF THE DUCTILE POLYMERS.
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