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采用频率为10 Hz、应力比为0.1的正弦波研究了室温下循环次数对二维炭毡C/C复合材料(2D炭毡C/C复合材料)的弯曲疲劳强度的影响,并利用偏光显微镜和扫描电子显微镜对该材料的热解碳组织形貌以及疲劳前后的断口形貌和微观结构进行了观察。结果表明,2D炭毡C/C复合材料的热解碳结构由光滑层和各向同性层组成,其疲劳极限为76.5 MPa,是静态弯曲强度的90%。在不同循环周次的疲劳载荷作用后,材料的剩余弯曲强度和韧性都得到了提高。在疲劳加载过程中,纤维/基体的界面结合强度发生弱化,纤维的协同承载能力得到提高,使C/C复合材料出现了疲劳强化现象。
The effect of cycle times on the flexural fatigue strength of two-dimensional carbon felt C / C composites (2D carbon felt C / C composites) was studied by using a sine wave at a frequency of 10 Hz and a stress ratio of 0.1. Polarization microscopy And scanning electron microscopy were used to observe the pyrolytic carbon microstructure of the material and the fracture morphology and microstructure before and after fatigue. The results show that the pyrocarbon structure of 2D carbon felt C / C composites consists of smooth and isotropic layers with a fatigue limit of 76.5 MPa and a static bending strength of 90%. The residual flexural strength and toughness of the material have been improved after the fatigue load in different cycles. During the process of fatigue loading, the bonding strength of fiber / matrix was weakened, and the synergistic load carrying capacity of the fibers was increased, which resulted in fatigue strengthening of C / C composites.