三维机织角联锁SiCf/SiC复合材料弯曲性能及损伤机制

Bending property and damage mechanism of three-dimensional woven angle interlock SiCf/SiC composites

为解决陶瓷基复合材料在服役环境中由于弯曲而导致失效的问题,从理论上分析了经向和纬向弯曲过程中复合材料弯曲受力与内部纤维之间的相互作用机制。以SiCf/SiC复合材料为例,利用微计算机断层扫描技术获得其内部纤维结构和孔隙等三维图像;并在此基础上,分别对三维机织角联锁SiCf/SiC复合材料经向和纬向进行弯曲性能测试,从细观、微观尺度分析弯曲损伤机制。结果表明:三维机织角联锁SiCf/SiC复合材料的纬向和经向性能明显不同,且纬向试样的弯曲强度大于经向试样;SiCf/SiC复合材料的弯曲损伤模式复杂,经向试样裂纹主要沿着经纱与纬纱接触点扩展,而纬向试样裂纹主要在纬纱束之间产生,并最终导致弯曲破坏。

Targeting at the bending failure of ceramic matrix composites in service environment,the interaction mechanism between the bending stress of the composite material and the internal fibers during warp and weft bending was theoretically analyzed.Taking SiCf/SiC composite materials as an example,three-dimensional(3-D)images of internal fiber structure and pores were obtained using micro computed tomography.On this basis,the warp and weft directions of the three-dimensional woven angle interlock SiCf/SiC composite were tested respectively,and the bending damage mechanism was analyzed in the meso and micro scales.The results show that weft and warp performance of SiCf/SiC composite are significantly different,and the bending strength of the weft specimen is larger than that of the warp specimen.The bending damage modes of 3-D woven angle interlock SiCf/SiC composites are complex,in which the warp cracks mainly propagate at the warp and weft contact points,while the cracks of weft specimen mainly occur between the weft bundles,eventually leading to bending failure.