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The University of Tokyo

东京大学

基本信息

批准号：
09555198
负责人：
TAKEDA Nobuo
金额：
$ 7.87万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09555198/
关键词：
Elevated Temperature Polymer Matrix Composites Damage Mechanics Transverse Crack Delamination Micro-mechanics Soft X-ray Replica 軟X線

项目摘要

A damage mechanics analysis was used to derive the energy release rate associated with matrix cracking and average stress of cracked plies. Matrix crack density as function of laminate stress was predicted based on both energy and average stress criteria. Laminate strain increment caused by matrix cracking was also derived as a function of applied laminate stress and matrix crack density, and the relation between laminate stress and strain could be predicted considering matrix cracking.Microscopic damage progress under static tensile loading was observed to study the effect of matrix resin, stacking sequence and temperature, experimentally. The analytical prediction of matrix crack behavior and the relation between laminate stress and strain were compared with the experimental results obtained. Analytical predictions for matrix crack behavior were in good agreement with experimental results. However, analytical prediction underestimated the laminate stress, because strain increment associated with matrix crack opening displacement is overestimated in this analysis. An advantage of the present predictive method is that it can be applied to laminates with arbitrary stacking sequences.Microscopic damage progress behavior in quasi-isotropic CFRP laminates under fatigue tensile loading was also observed. The effect of stacking sequence on microscopic damages was investigated. Damage mechanics analysis was used to derive the energy release rate associated with matrix cracking. Matrix cracking behavior was modeled using modified Paris-law approach.Microscopic damage progress in cross-ply laminates under thermal fatigue loading was also investigated. Matrix cracks initiated in both O° and 90° plies and the number of cracks increased as the number of cycles increased. It was found that modified Paris law approach was effective far thin plies and average stress approach was effective for thick plies.

采用损伤力学分析方法，推导出与基体开裂和开裂层平均应力相关的能量释放率。基于能量准则和平均应力准则预测了基体裂纹密度随层合板应力的变化。通过对基体开裂引起的层合板应变增量与层合板应力和基体裂纹密度的关系进行推导，预测了基体开裂引起的层合板应力应变关系，并通过静态拉伸试验观察了基体树脂、铺层顺序和温度对层合板损伤的影响。对基体裂纹行为和层合板应力应变关系的解析预测与实验结果进行了比较。基体裂纹行为的分析预测与实验结果吻合良好。然而，分析预测低估了层压应力，因为应变增量与基体裂纹张开位移是高估了在这个分析。该方法的优点是可以适用于任意铺层顺序的层合板，并观察了准各向同性CFRP层合板在疲劳拉伸载荷下的细观损伤发展行为。研究了叠层顺序对微观损伤的影响。采用损伤力学分析方法推导了基体开裂时的能量释放率。采用修正的Paris-law方法模拟了基体开裂行为，研究了热疲劳载荷作用下正交铺设层合板的细观损伤过程。基体裂纹在0 °和90°铺层中均萌生，裂纹数量随循环次数的增加而增加。结果表明，修正的巴黎定律法适用于较薄的铺层，平均应力法适用于较厚的铺层。