3D针刺C/SiC断裂韧性缺口敏感性及破坏研究

碳化硅陶瓷基复合材料是高超声速飞行器及高推重比发动机等发展所需的关键材料之一，对冲击断裂韧性、缺陷及裂纹的敏感性有较高要求。采用夏比冲击试验测定3D 针刺C/SiC 复合材料的断裂韧性，研究其处于U 型、V 型缺口分别在与针刺平行、垂直的不同分布方向时对冲击断裂韧性的影响，并通过扫描式电子显微镜及光学显微镜等手段详细分...

Study on notch sensitivity and failure of 3D needled C/SiC fracture toughness

SiC ceramic matrix composites are one of the key materials for the development of hypersonic aircraft and engines with high thrust/weight ratio, which have high requirements for impact fracture toughness, defect and crack sensitivity. In this paper, Charpy impact test was used to measure the fracture toughness of 3D needled C/SiC composites. The effects of U-shaped notch and V-shaped notch on the impact fracture toughness were studied in different distribution directions parallel to and perpendicular to the needling, and the fracture morphology was analyzed in detail by means of scanning electron microscope and optical microscope. The fracture toughness of the material with U-shaped notch is more sensitive to the relative position of the notch line and the needle than that of V-shaped notch, and the fracture toughness is the worst when the notch line is parallel to the needle fiber bundle, and the fracture toughness is higher when the notch line is vertical. From the fracture, it is found that the intersection of needle fiber bundle and 0° and 90° non-woven cloth layup is relatively weak, and the shear resistance of raw materials is weakened. The notch line is parallel to the impact section of the acupuncture and parallel to the plane of the notch, and the fiber bundles are pulled out long and many. The notch line is perpendicular to the impact section of the acupuncture, and the uniform appearance is oblique section. The pulled-out fiber bundles are short and less, and there is obvious stratification phenomenon.