2D-C/SiC复合材料面内剪切性能统计及强度B基准值

针对2D-C/SiC复合材料进行大子样面内剪切实验,研究材料面内剪切模量和强度的分布规律及强度B基准值。运用线性回归结合假设检验的方法,确定2D-C/SiC复合材料面内剪切力学性能的分布规律及参数,对比两种不同经验失效概率得到统计结果;通过观察试样最窄净截面微CT照片及断口电镜扫描照片,解释材料面内剪切强度分散性微观机制,基于分布规律,最终计算得到2D-C/SiC复合材料面内剪切强度威布尔B基准值。结果表明:强度和模量均同时服从威布尔、正态和对数正态分布,且理论模型与实验结果吻合良好,两种经验失效概率不影响力学性能分布规律;面内剪切强度分散性与最窄净截面致密度和界面脱粘长度有关;2D-C/SiC复合材料面内剪切强度威布尔B基准值为80.41MPa。

In-plane shear performance statistics of 2D-C/SiC composites and its B-basis value of strength

The distribution of in-plane shear modulus and strength of 2D-C/SiC composites,and its B-basis value of strength were studied by testing thirty Iosipescu specimens under shear load.The distribution and parameters about in-plane shear properties of 2D-C/SiC composites were determined by the method that liner regression combined with hypothesis testing,and the statistics results obtained by two different empirical failure probabilities were compared.The mechanism of the dispersibility of the in-plane shear strength was demonstrated by the micro-CT(μ-CT)photographs and SEM(scanning electron microscope) photographs through observation on the narrowest net cross-section.Finally,the Weibull B-basis value of the strength was calculated based on the distribution law.The results show that the strength and modulus of 2D-C/SiC composites both follow weibull,normal and lognormal distribution,and the prediction has good agreement with test data.The distribution of the mechanical properties is not affected by two empirical failure probabilities.The dispersibility of the strength is connected with the density of the narrowest net cross-section and the interface debonding length.Finally,its B-basis value of strength is 80.41MPa.