Influence of interface debonding on matrix cracking of cross-ply SiC/CAS composites
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摘要: 采用细观力学方法研究了正交铺设SiC/CAS复合材料在单轴拉伸载荷作用下界面脱粘对基体开裂的影响。采用断裂力学界面脱粘准则确定了0°铺层纤维/基体界面脱粘长度, 结合能量平衡法得到了主裂纹且纤维/基体界面发生脱粘(即模式3)和次裂纹且纤维/基体界面发生脱粘(即模式5)的临界开裂应力, 讨论了纤维/基体界面剪应力、 界面脱粘能对基体开裂应力的影响。结果表明, 模式3和模式5的基体开裂应力随纤维/基体界面剪应力、 界面脱粘能的增加而增加。将这一结果与Chiang考虑界面脱粘对单向纤维增强陶瓷基复合材料初始基体开裂影响的试验研究结果进行对比表明, 该变化趋势与单向SiC增强玻璃陶瓷基复合材料的试验研究结果一致。Abstract: The influence of interface debonding on matrix cracking of cross-ply SiC/calcium alumino silicate glass (CAS) composites under uniaxial tensile loading was studied by micromechanics approach. The fracture mechanics interface debonding criterion was used to determine the interface debonding length in the 0? ply. When cross-ply ceramic matrix composites are under tensile loading, transverse cracking in the 90? ply and matrix cracking in the 0? ply occur. Based on the difference of the transverse crack and matrix crack, the damage states in cross-ply laminates can be classified into five modes. The mode 3 cracking mode contains transverse cracking, matrix cracking and fiber/matrix interface debonding. The mode 5 cracking mode only contains matrix cracking and fiber/matrix interface debonding. The critical stress of mode 3 and 5 was determined using the energy balance method. The effects of interface shear stress and interface debonding energy on matrix cracking stress have been analyzed. The conclusions that the initial cracking stress of mode 3 and 5 increases as the interface shear stress and interface debonding energy increases was gotten. The analysis was compared with the experimental result of unidirectional fiber-reinforced ceramic matrix composites done by Chiang. The predicted trend of cross-ply ceramic matrix composites is consistent with the experimental results of unidirectional ceramic matrix composites.
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Keywords:
- ceramic matrix composites /
- cross-ply /
- matrix cracking /
- interface debonding /
- micromechanics
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