Effect of cycles on flexural fatigue strength for 2D C/C composites
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摘要: 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。
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关键词:
- 二维炭毡C/C复合材料 /
- 弯曲疲劳 /
- 剩余强度 /
- 断裂行为 /
- 疲劳强化
Abstract: The effect of cycles on the flexural fatigue strength for 2D carbon-felt C/C composites at room temperature was studied under the sinusoidal loading frequency of 10 Hz and stress ratio of 0.1.The microstructure of the pyrolytic carbon and the morphology of the fractured surfaces of the samples before and after being fatigued were observed by polarized light microscope(PLM) and SEM. The results show that the pyrolytic carbon consists of smooth laminar and isotropic structure. The fatigue limit of 2D carbon-felt reinforced carbon composites is found to be 76.5 MPa, 90% of the static flexural strength. The residual flexural strength and toughness of the materials after being fatigued are improved. The fiber/matrix interface bonding strength is weaken during fatigue-loading, while collaborative carrying capacity of fiber is improved. Therefore, the fatigue strength-enhancing behavior of C/C composites appears.-
Key words:
- 2D carbon-felt C/C composites /
- flexural fatigue /
- residual strength /
- fracture behaviors /
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