预氧化Cf/SiC陶瓷基复合材料及其构件的抗疲劳特性研究

采用在线销钉集成技术实现了二维C_f/SiC复杂构件的近尺寸成型,并考察预氧化C_f/SiC销钉集成构件的高周疲劳寿命及破坏模式。实验结果表明:C_f/SiC构件在不同激振加速度条件下均表现为由销钉断裂所引起的整体分层破坏,层板连接处为C_f/SiC构件的振动疲劳薄弱部位。通过ANSYS振动应力分析和微观组织分析可以推论出,疲劳试验时,裂纹容易沿着层板间的基体扩展,在基体开裂失效后,全部应力施加于销钉处,最终在疲劳应力作用下销钉发生断裂,导致构件整体分层破坏。

Anti-fatigue Performance Study of Pre-oxidized 2D-Cf/SiC Ceramic Matrix Composites

In this paper, the two-dimensional (2D) carbon fiber reinforced silicon carbide matrix composites (C_f/SiC) with complex shape were prepared by the online integration technique, and then the vibration fatigue test was carried out to investigate the vibration fatigue life and damage models after the pre-oxidation. The work demonstrated the delamination damage mode at different excitation acceleration, which was caused by the pin fracture, and the delamination joint is weak part of C_f/SiC. Through the analysis of ANSYS stress and microstructure, it can be concluded that, in the vibration test, cracks propagated easily in the interlayer matrix due to the lack of fiber toughening mechanism, and then the stress was concentrated on the pin with the failure of interlayer matrix. So the composites failed by the pin fracture and the interlayer delamination were damaged.