2D-SiC_f/SiC 复合材料层间 I 型断裂试验及表征

Two-dimensional braided silicon carbide fiber reinforced composite material (2D SiC_f/SiC) is widely used in the aerospace field. However, owing to its weak interlaminar mechanical properties, this material is prone to initiation of interlaminar cracks and delamination failure. Therefore, a comparative study on the Wedge-loaded Double Cantilever Beam method (W-DCB) and the classical Double Cantilever Beam method (DCB) was conducted. The loading data of interlaminar crack-driving were obtained, and the relationship curve of crack opening force and opening displacement were obtained. During the loading, the visual crack propagation process was monitored through an optical microscope, which was to explore the interlaminar crack growth behaviors. Combined the theoretical analysis and the visual characteristics of the crack, the meaning of the inflection point and other characteristic points of the relationship curve is explained. What’s more, scanning electron microscope was used to analyze the characteristics of the interlaminar fracture surface to reveal growth mechanism of the delamination crack in the fracture surface. The results show that the W-DCB method is equivalent to the DCB method in measuring the initial energy release rate of interlaminar Mode I fracture in 2D-SiC_f/SiC; In terms of 2D-SiC_f/SiC interlaminar Mode I fracture, the multi-peak characteristic of deformation curve is not according with the post-peak loading curve predicted by classical linear elastic Fracture mechanics, which reflects complexity of interlaminar constraint relationship. The interlaminar section is structurally non-completely damaged, but still emerging local fiber-bridgings.