编织密度对2D-SiCf/SiC力学行为的影响与机制

Effect and mechanism study of woven density on mechanical behavior of a 2D-SiCf/SiC

  • 摘要: 编织陶瓷基复合材料逐渐成为提升航空发动机综合性能的热门材料。材料的失效机制分析为材料/结构的性能设计与优化提供着重要的理论与方法支持。本文针对不同编织密度的2D-SiCf/SiC复合材料开展室温拉伸试验,通过对力学行为、损伤演化进行对比分析,研究编织复合材料的力学行为及内在的损伤机制。结果表明:比例极限应力随着横向纤维束编织密度的增加逐渐降低,纵向纤维束编织密度对比例极限应力影响较小;纵向纤维编织密度较小时,拉伸强度较低,随着纵向编织密度的增加,拉伸强度增大并趋于稳定,横向纤维编织密度的增加,对拉伸强度有一定的弱化作用;根据拉伸应力/应变的演化过程,编织SiCf/SiC复合材料的拉伸过程可以划分为4个典型阶段;缝合孔对材料的拉伸强度有一定弱化作用,需要在材料制备、后处理过程中消除缝合孔的不利影响。

     

    Abstract: Woven ceramic matrix composites have gradually become a popular material for improving the comprehensive performance of aero-engines. Failure mechanism analysis of materials provides important theoretical and methodological support for material/structure performance design and optimization. In this paper, the tensile tests of 2D-SiCf/SiC composites with different woven densities were carried out at room temperature, and the mechanical behavior and damage mechanism of the woven composites were studied. The results show that: The proportional limit stress decreases gradually with the increase of the transverse fiber bundle woven density, and the longitudinal fiber bundle woven density has little effect on the proportional limit stress. When the density of longitudinal fiber is small, the tensile strength is low. With the increase of longitudinal fiber density, the tensile strength increases and tends to be stable, while the increase of transverse fiber density has a certain weakening effect on the tensile strength. According to the evolution of tensile stress/strain, the tensile process of the woven SiCf/SiC composites can be divided into four typical stages. The stitching hole has a certain weakening effect on the tensile strength of the material, so it is necessary to eliminate the adverse effect of the stitching hole in the material preparation and post-treatment process.

     

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