Size Effect of Strength for SiC/SiC Composites: Experimental Study and Theoretical Analysis

• Published in: Applied composite materials Vol. 28; no. 5; pp. 1381 - 1398
• Main Authors: Zhang, Sheng, Meng, Weikang, Gao, Xiguang, Song, Yingdong, Zhang, Zhiguo
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.10.2021; Springer Nature B.V
• Subjects: Aeronautics; Bearing strength; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Composite materials; Fracture surfaces; Industrial Chemistry/Chemical Engineering; Interfacial shear stresses; Laboratories; Load carrying capacity; Materials Science; Polymer Sciences; Shear stress; Size effects; Stress concentration; Stress distribution; Tensile strength; Ceramic matrix composites; Theoretical analysis; Experimental study; Strength; Size effect
• ISSN: 0929-189X; 1573-4897
• DOI: 10.1007/s10443-021-09915-w

The size effect of the strength for SiC/SiC composites must be considered when measuring the strength of this material using a specimen. However, the size effect and its micro-mechanisms are still unclear at present. The size effect is studied using minicomposites through experimental investigation and theoretical analysis. The strengths of specimens with different lengths are measured and it is found that the size effect of the strength for SiC/SiC composites is not remarkable. To explain this phenomenon, the distribution of fiber flaws and the stress distribution of broken fibers are analyzed. It is found that owing to the fiber/matrix interfacial shear stress, broken fibers still have the load carrying capacity and then the effected region of each fiber flaw is limited. This mechanism decreases the sensitivity of SiC/SiC composites to the size effect. A fracture model of SiC/SiC composites is developed according to this mechanism. The predicted strength, stress–strain response and fracture surface match well with the experimental results.