平纹编织C/SiC复合材料层间断裂行为试验研究

EXPERIMENTAL INVESTIGATION ON INTERLAMINAR FRACTURE BEHAVIOR OF PLAIN WEAVE C/SIC COMPOSITES

通过双悬臂梁和端部切口弯曲试验分别对平纹编织C/SiC复合材料的Ⅰ型(张开型)和Ⅱ型(滑开型)层间断裂行为进行试验研究,得到该材料以临界能量释放率GⅠC和GⅡC表征的层间断裂韧度值。试验后利用光学显微镜对两组试验的试样断口进行显微观察,以分析其破坏机理。结果表明:Ⅰ型层间断裂韧度值GⅠC和Ⅱ型层间断裂韧度值GⅡC分别为(737.2±57)J/m2和(1 082.7±90)J/m2;Ⅰ型开裂为层间SiC基体沿初始裂纹方向的断裂破坏;Ⅱ型开裂与Ⅰ型开裂相似,但裂纹上下表面包裹碳纤维束的SiC基体发生脱落,并且出现碳纤维束中部分碳纤维剪切破坏。

Double cantilever beam（DCB） and end notched flexure（ENF） experiments were performed to investigate the mode Ⅰand mode Ⅱ interlaminar fracture behavior of plain weave C/SiC composites,respectively.The fracture toughnesses of the two interlaminar fracture modes characterized by critical energy release rate GⅠC and GⅡC were obtained.After experiments,specimen fracture surfaces of the two groups of experiments were observed by optical microscope to analyze their fracture mechanisms.The experimental results indicate that,mode Ⅰ fracture toughness and mode Ⅱfracture toughness are about（737.2±57）J/m^2 and（1 082.7±90）J/m^2,respectively.Interlaminar matrix fracture along the initial crack is the main fracture mechanism of mode Ⅰ fracture.Mode Ⅱ fracture has the same main fracture mechanism as that of mode Ⅱ fracture.Moreover,SiC matrix around the C bundle fell off partially and part of the C bundle was sheared to failure.