QUANTITATIVE MICROMECHANISTIC STRESS AND DEFORMATION ANALYSIS OF ENVIRONMENTAL CRAZES IN CRACKED POLYMERS BY USING THE SHADOW-OPTICAL-METHOD OF CAUSTICS

本文对有机玻璃裂纹前的甲醇银纹进行了实验应力和变形分析。结论如下。结果表明，利用焦散线，阴影光学图案。2.拉伸下裂纹阴影图案的变化与其面外变形的变化有很好的对应关系.已经证实在裂纹尖端存在应力集中，这意味着Dugdale模型的使用对于断裂力学来说有其局限性.对于从甲醇中取出到空气中并干燥的试样的裂纹尖端变形，允许采用弹性近似。银纹层的应力分布与克雷默等人用全息干涉法得到的结果吻合得很好.环境银纹的生长速率与阴影图案的直径有关.建立了银纹层应力分布的数学模型，并在此基础上进行了预测银纹的计算机模拟。通过与实验结果的拟合，可以得到裂纹尖端和银纹尖端的应力等参数.本文研究了受拉裂纹板的应力光学常数与周围环境介质折射率的关系。它已被证明，光学效果的蝗虫是不可忽视的。从聚乙烯？的裂纹尖端获得了反射焦散图案。IER合金，它有可能提高韧性聚合物的韧性。

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.