This study analyzed the influence of the sample volume, number of tested specimen, and testing method on the flexural strength of fabric-reinforced ceramic matrix composites. For this purpose, seven different batches of C/C-SiC were prepared with four different sample thicknesses to determine the flexural strengths and Weibull moduli by three- and four-point flexural tests. The result showed that C/C-SiC exhibits a size effect of strength under bending load because a decrease of measured flexural strength with increased specimen size was observed. This size effect was discussed regarding the Weibull weakest link approach and the concept of quasi-brittle materials.The determined Weibull moduli were comparable for the same load condition but dissimilar for the identical material if the load condition were changed from three- to four-point bending. Hence, the Weibull modulus was found to be not an inherent material constant for C/C-SiC and the Weibull weakest link approach seems not appropriate.

本研究分析了试样体积、试样数量和测试方法对织物增强陶瓷基复合材料抗弯强度的影响。为此，制备了具有四种不同样品厚度的七批不同批次的 C/C-SiC，以通过三点和四点弯曲试验确定弯曲强度和威布尔模量。结果表明，C/C-SiC 在弯曲载荷下表现出强度的尺寸效应，因为观察到测量的弯曲强度随着试样尺寸的增加而降低。关于威布尔最弱连接方法和准脆性材料的概念讨论了这种尺寸效应。 确定的威布尔模量对于相同的载荷条件具有可比性，但如果载荷条件从三点变为四点，则对于相同的材料则不同弯曲。