Meso-Mechanical Analysis of Fatigue Crack Propagation in CFRP under Mixed-Mode Loading

混合模式加载下 CFRP 疲劳裂纹扩展的细观力学分析

• 批准号: 07455052
• 负责人: TANAKA Keisuke
• 金额: $ 5.31万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07455052/
• 关键词: Composite Materials; CFRP; Mixed-Mode Loading; Fatigue Crack Propagation; Meso-Mechanics; Fracture Mechanics; Matrix-Phase Stress; Fractography; 層間はく離

1. Mixed-mode (I+II) interlaminar fatigue tests were conducted by the mixed mode bending (MMB) method with unidirectional graphite/epoxy laminates. The effects of the mixed-mode ratio and the stress ratio on the crack propagation behavior were studied from a viewpoint of fracture mechanics.2. Devices for the in-situ SEM examination of the fatigue crack propagation under mode I,II and mixed-mode (I+II) loadings were developed.3. Fractographic observations were conducted to examine micromechanisms of the mixed-mode propagation of interlaminar fatigue cracks in graphite/epoxy laminates. A mode for the fatigue crack propagation was proposed on the basis of microprocesses of initiation, growth and coalescence of the matrix microcracks.4. A numerical technique for the meso-mechanical analysis of interlaminar cracks in FRP laminates was developed. The boundary element method is used for the meso-mechanical elastic analysis. In this analysis, the near-tip region of an interlaminar crack is modeled by the inhomogeneous FRP model composed of isotropic matrix and orthotropic fibers which is surrounded by the homogenized orthotropic FRP phase.5. By using the above meso-mechanical model of FRP laminates, the analysis of the elastic stress distribution near the tip of an interlaminar crack subjected to mode I and II loadings was conducted. For long cracks, the energy release rate obtained for the meso-mechanical FRP model is equal to that obtained for the homogeneous model. The distribution of the matrix-phase stress ahead of the crack tip for the meso-mechanical model is greatly different from that for the homogeneous model. Therefore, the meso-mechanical analysis is essential for investigation on microfracture of matrix and fiber/matrix interfaces of FRP composites.

1. 采用混合模弯曲（MMB）方法，对单向石墨/环氧复合材料进行了混合模（I+II）层间疲劳试验。从断裂力学的角度研究了混合模态比和应力比对裂纹扩展行为的影响。研制了I型、II型和混合（I+II）型加载下疲劳裂纹扩展的原位SEM检测装置。通过断口观察，研究了石墨/环氧复合材料层间疲劳裂纹混合模式扩展的微观机制。基于基体微裂纹的萌生、扩展和聚并等微过程，提出了疲劳裂纹扩展模式。提出了一种用于玻璃钢层间裂纹细观力学分析的数值方法。采用边界元法进行细观力学弹性分析。在本分析中，层间裂纹的近尖端区域采用了由各向同性基体和正交异性纤维组成的非均匀FRP模型，该模型被均质正交异性FRP相包围。利用上述FRP复合材料细观力学模型，对ⅰ型和ⅱ型加载下层间裂纹尖端附近的弹性应力分布进行了分析。对于长裂纹，细观力学FRP模型得到的能量释放率与均匀模型得到的能量释放率相等。细观力学模型的裂纹尖端前基体相应力分布与均匀力学模型有很大不同。因此，细观力学分析是研究FRP复合材料基体和纤维/基体界面微断裂的必要手段。

项目成果

Hiroshi Tanaka: "Mixed-Mode Growth of Interlaminar Cracks in Carbon/Epoxy Laminates under Cyclic Loading" Proc. 10th Int. Conf. Comp. Mater.Vol. I. 181-188 (1995)

Hiroshi Tanaka：“循环加载下碳/环氧树脂层压板中层间裂纹的混合模式增长”Proc。

田中啓介: "モードIIき裂を有する長繊維強化複合材料のマトリックス相応力分布の解析" 日本機械学会講演論文集. 96-10. 9-10 (1996)

Keisuke Tanaka：“具有 II 型裂纹的长纤维增强复合材料中的基体相应力分布分析”日本机械工程师学会会议记录 96-10 (1996)。

Keisuke Tanaka: "Near-Threshold Propagation of Delamination Fatigue Cracks" Materials Science Research International. 1. 100-107 (1995)

Keisuke Tanaka：“分层疲劳裂纹的近阈值传播”国际材料科学研究。

田中 拓: "高強度CFRP積層板の混合モード層間疲労破壊特性" 日本機械学会講演論文集. 96-1. 69-70 (1996)

Taku Tanaka：“高强度 CFRP 层压板的混合模式层间疲劳断裂特性”，日本机械工程师学会会议记录 96-1（1996）。

Keisuke TANAKA,Hiroshi TANAKA and Hidetaka KATO: "Fractography of Mixed-Mode Interlaminar Fatigue Fracture of CFRP Laminates" Proc.20th Symp.on Comp.Mater.55-56 (1995)

Keisuke TANAKA、Hiroshi TANAKA 和 Hidetaka KATO：“CFRP 层压板混合模式层间疲劳断裂的断口分析”Proc.20th Symp.on Comp.Mater.55-56 (1995)