UNIAXIAL MACRO-MECHANICAL PROPERTY AND FAILURE MODE OF A 2D-WOVEN C/SiC COMPOSITE
UNIAXIAL MACRO-MECHANICAL PROPERTY AND FAILURE MODE OF A 2D-WOVEN C/SiC COMPOSITE
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发表时间：
2005
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通讯作者：
Jiao Guiqiong
中科院分区：
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作者：
Jiao Guiqiong
通过单向拉伸和压缩加载和卸载试验，研究了用CVI工艺制备的二维机织C/SiC复合材料的宏观力学行为。研究了复合材料的弹性模量、残余应变和泊松比的变化，以进一步表征复合材料在复杂应力状态下的力学性能。利用扫描电镜和光学显微镜分析了材料的失效模式和损伤机理。拉伸试验结果表明，在40 MPa左右的低拉应力水平下，材料开始出现损伤，卸载模量和泊松比随拉应力的增加而线性减小，而残余应变则随拉应力的增加而增大。断口分析表明，0°纤维束周围的基体裂纹和层间裂纹是主要的损伤机制。压缩行为几乎与破坏成线性关系。压缩模量和泊松比保持不变。拉伸试样以韧性断裂方式断裂，主要是由于分层、纵束断裂和拔出。平面内的整体压缩破坏与加载方向成13°，由于束间和90°束内的裂纹，0°束被剪切破坏。
The macro-mechanical behavior of 2D-woven C/SiC composites produced with CVI technique was investigated by loading and unloading uniaxial tensile and compress tests. The changes in elastic modulus, residual strain, and Poisson ratio were studied for further characterization of mechanical properties of the CMCs in complex stress states. Failure mode and damage mechanisms were analyzed by SEM and optical microscope. The tensile tests show that damage begins at a very low tensile stress level of about 40MPa, and that the unloading modules and Poisson ratio decrease linearly as the tensile stress increases, while the residual strain increases. Fractography analysis shows that matrix cracks around the 0° fiber bundles and interlaminar cracks are the main damage mechanisms. The compress behavior is almost linear to failure. The compress modulus and Poisson ratio remain constant. The tensile specimens break in a ductile manner, because of delamination, longitudinal bundles failure and pull out. The global compress failure in a plane orients about 13° to the loading direction, and because of cracks between bundles and within the 90° bundles, the 0° bundles are sheared to failure.