Effect of interlaminar and intralaminar structure on fracture of high strength CFRP and optimization of mesoscopic structure

研究了层间和层内细观结构对CFRP复合材料断裂韧性和抗疲劳裂纹扩展性能的影响。在本研究中，控制了预浸料界面的树脂层数和纤维/基体界面强度。通过层间和层间断裂性能的比较，找出富树脂层在预浸料界面上的作用。研究了一种由热塑性细颗粒和基层环氧树脂组成的新型富树脂层用非均相树脂。最后，分别分析了预浸界面富树脂层厚度和韧性对预浸界面富树脂层的影响，并对富树脂层的优化进行了探讨。研究结果总结如下：1。在预浸界面添加非均相树脂的CFRP复合材料的II型层间性能研究断裂韧性和抗疲劳裂纹扩展能力提高到添加韧性较强的热塑性树脂的水平。这种高韧性随裂纹扩展的增加而保持。在CFRP层压板的预浸界面上研究了热塑性树脂交织CFRP的I型和II型层间性能。I型断裂韧性与热塑性树脂基CFRP复合材料基本相同。这种高韧性随裂纹扩展的增加而保持。模态II的韧性大于10kJ/m^2，远高于热塑性树脂基CFRP复合材料的韧性。纤维/基体界面强度对层间和层内断裂性能的影响I型层间断裂韧性随表面处理水平的增加而增加。II型层间试验中，表面处理对断裂韧性的影响小于I型层间试验。I型层间断裂韧性对CF/环氧复合材料的表面处理水平不敏感。SEM观察表明，细观断裂机制与表面处理效果密切相关。少

Effects of interlaminar and intralaminar mesoscopic structures on the fracture toughness and fatigue crack growth resistance were investigated for CFRP laminates. In the present study, resin layrs at the prepreg interfaces and fiber/matrix interfacial strength were controlled. Comparison of interlaminar and intralaminar fracture properties was carried out to find out the role of resin rich layrs at the prepreg interface. A new type of heterogeneous resin for resin rich layrs which is composed of thermoplastic fine particles and epoxy of base lamina was also investigated. Finally, the effect of thickness and toughness of the resin rich layrs at the prepreg interface was separately analyzed, and the optimization of the resin rich layrs was discussed. The results are summarized as follows :1.Mode II interlaminar properties of CFRP laminates with heterogeneous resin at prepreg interfaceFracture toughness and fatigue crack growth resistance were improved up to the level of CFRP laminates wi … More th tough thermoplastic resin. This high toughness was kept with the increment of crack growth.2.Mode I and II interlaminar properties of thermoplastic resin interleaved CFRPPolyethylene base thermoplastic resin was put at the prepreg interface of CFRP laminates. The mode I fracture toughness was almost the same as that for CFRP laminates with thermoplastic resin matrix. This high toughness was kept with the increment of crack growth. For the case of mode II,the toughness was more than 10kJ/m^2, which was much higher than that for CFRP laminates with thermoplastic resin matrix.3.Effect of fiber/matrix interfacial strength on interlaminar and intralaminar fracture propertiesThe fracture toughness for mode I intralaminar tests increased with increasing surface treatment levels. The effect of the surface treatment on the fracture toughness for mode II interlaminar tests was smaller than that for mode I intralaminar tests. The fracture toughness for mode I interlaminar tests was insensitive to the surface treatment level for CF/epoxy laminates. The mesoscopic fracture mechanism was well correlated to the effect of the surface treatment on the basis of SEM observation. Less