Basic Study on Remaining Strength Evaluation of Advanced Composite Materials Damaged by Severe Earthquake Loading

强震荷载损伤的先进复合材料剩余强度评估基础研究

• 批准号: 08650112
• 负责人: NAKAI Yoshikazu
• 金额: $ 1.41万
• 依托单位: Kobe University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650112/
• 关键词: Delamination; Fatigue Crack Propagation; Thermo-mechanical Fatigue; Interfacial Shear Stress; Surface Treatment; Unidirectional CFRP; Fracture Toughness; Composite Material; 先進複合材料; 強度評価; 層間はく離; 疲労強度

Constant DELTAK fatigue crack propagation tests were conducted with double cantilever baam (DCB) specimens made of two kinds of unidirectional CF/epoxy laminates. The effects of loading frequency, test temperature, and environment on the interlaminar delamination fatigue crack growth were investigated. The effect of cyclic frequency was not observed in air. The effect of test temperature was found to depend on material and environment. The interlaminar fatigue crack propagation rate was lower for higher angle between fiber and crack propagation direction. The rate also depended on specimen width.Fatigue crack propagation rate accelerated after overloading while it usually decelerates in metallic materials. Crack tip shielding by fiber bridging may diminish (or minimize) by overloading.In addition to the continuous fiber reinforced plastic mentioned above, stress relaxtion tests of short glass fiber reinforced plastics (GFRP), which is widely employed in engineering products, were conducted to evaluate interfacial shear stress. Based on the visco-elastic model and stress relaxation tests, the effects of surface treatment, strain rate, mixing pressure on tensile and fatigue properties were analyzed.

使用由两种单向 CF/环氧树脂层压板制成的双悬臂梁 (DCB) 样本进行恒定 DELTAK 疲劳裂纹扩展测试。研究了加载频率、试验温度和环境对层间分层疲劳裂纹扩展的影响。在空气中没有观察到循环频率的影响。发现测试温度的影响取决于材料和环境。纤维与裂纹扩展方向之间的角度越大，层间疲劳裂纹扩展速率越低。该速率还取决于试样宽度。过载后疲劳裂纹扩展速率加快，而金属材料中的疲劳裂纹扩展速率通常减慢。纤维桥接的裂纹尖端屏蔽可能会因过载而减弱（或最小化）。除了上述连续纤维增强塑料外，还对工程产品中广泛采用的短玻璃纤维增​​强塑料（GFRP）进行了应力松弛测试，以评估界面剪切应力。基于粘弹性模型和应力松弛试验，分析了表面处理、应变速率、混合压力对拉伸和疲劳性能的影响。