正交铺设陶瓷基复合材料单轴拉伸行为

采用细观力学方法对正交铺设陶瓷基复合材料单轴拉伸应力-应变行为进行了研究。采用剪滞模型分析了复合材料出现损伤时的细观应力场。采用断裂力学方法、 临界基体应变能准则、 应变能释放率准则及Curtin统计模型4种单一失效模型确定了90°铺层横向裂纹间距、 0°铺层基体裂纹间距、 纤维/基体界面脱粘长度和纤维失效体积分数。将剪滞模型与4种单一损伤模型结合, 对各损伤阶段应力-应变曲线进行了模拟, 建立了复合材料强韧性预测模型。与室温下正交铺设陶瓷基复合材料单轴拉伸应力-应变曲线进行了对比, 各个损伤阶段的应力-应变、 失效强度及应变与试验数据吻合较好。分析了90°铺层横向断裂能、 0°铺层纤维/基体界面剪应力、 界面脱粘能、 纤维Weibull模量对复合材料损伤及拉伸应力-应变曲线的影响。 

Uniaxial tensile behavior of cross-ply ceramic matrix composites

The uniaxial tensile stress-strain behavior of cross-ply ceramic matrix composites has been investigated using a micro-mechanical approach. The shear-lag model was adopted to obtain the micro stress field of the damaged composites. The fracture mechanics approach, critical matrix strain energy criterion, strain energy release rate criterion and Curtin’s statistical approaches were used to determine transverse crack space of 90° ply, matrix crack space of 0° ply, fiber/matrix interface debonded length and fiber failure volume fraction. By combining the shear-lag model with the failure criterion, the tensile stress-strain curve of each damage stage was modeled, and the exact model of predicting the toughness and strength of the composite was established. The uniaxial tensile stress-strain curve of cross-ply ceramic matrix composite at room temperature was compared with the present analysis. The stress-strain curve of each damage stage, the failure strength and failure strain agree well with the experimental data. The effects of fracture energy of 90° ply, fiber/matrix interface shear stress, interface debonded energy, and fiber Weibull modulus on the damage of the composite and the stress-strain curve were also investigated.