Plain weave planar and biaxially braided tubular SiC/SiC CMCs are evaluated in tension and four‐point bending, respectively, at ambient conditions. Custom‐designed fixtures for CMC testing are developed for each loading mode and are coupled with three‐dimensional digital image correlation. Stereoscopic image correlation analysis reveals crack initiation and failure sites to provide insight into stress redistribution mechanisms. Scanning electron microscopy is performed postmortem to determine the influence of microstructural features on crack initiation and failure. Crack spacing is measured in situ by stereoscopic image correlation and confirmed by SEM measurements to relate to underlying tow‐tow crossing points. Triangulated surface heights of plain weave tow architecture are used to determine that subtle differences in neighboring transverse tow angle, which vary within a range of ±4° from horizontal, have no significant effect on final fracture location. The results presented reaffirm the state of current SiC/SiC CMCs developed for energy applications and will help to further improve SiC/SiC and other CMCs.

中文翻译：

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在环境条件下用于能源应用的SiC / SiC复合材料的分析

在环境条件下，分别评估了平纹编织平面编织和双轴编织管状SiC / SiC CMC的拉伸和四点弯曲。针对每种加载模式开发了用于CMC测试的定制设计夹具，并与三维数字图像关联相结合。立体图像相关性分析揭示了裂纹萌生和破坏的位置，以提供对应力重新分布机制的洞察力。验尸后进行扫描电子显微镜检查以确定微观结构特征对裂纹萌生和破坏的影响。裂纹间距是通过立体图像相关性在原位测量的，并通过SEM测量来确认与下面的丝束-丝束交叉点有关。平织牵引结构的三角表面高度用于确定相邻横向牵引角的细微差异（与水平方向成±4°的范围内变化）对最终的裂缝位置没有明显影响。提出的结果重申了目前为能源应用开发的SiC / SiC CMC的状态，并将有助于进一步改善SiC / SiC和其他CMC。