界面性能对陶瓷基复合材料拉伸强度的影响

基于陶瓷基复合材料拉伸试验现象引入了主裂纹损伤带的概念, 并将其宽度定义为界面脱粘长度. 由于界面性能对纤维应力集中有较大影响, 并且控制着材料的断裂模式, 分别给出了脆性断裂和韧性断裂的强度计算公式, 并引入了应力集中系数和界面脱粘能量释放率. 分析结果表明, 拉伸强度随着应力集中系数和界面脱粘能量释放率的增大而减小. 文中公式给出的预测值与试验值吻合较好, 表明断裂时纤维所承担的应力用脱粘段纤维平均应力来衡量是合适的.

Effects of Interface Properties on Tensile Strength of Ceramic Matrix Composites

A definition of central crack damaged zone (CCDZ) is introduced based on tension experiments of Ceramic Matrix Composites (CMCs). The width of the CCDZ is defined to equal the debond length and the effect of interface toughness is neglected. When the CMCs rupture, the stress carried by the fibers can be estimated by the mean fiber stress within the CCDZ. Furthermore, the rule of mixtures is modified. Considering that the interface properties control the fracture mode, two kinds of models are presented respectively for brittle and ductile fracture strength. The stress concentration factor and interface debond energy release rate are introduced and discussed. It indicates that both the above factors result in decline of the tensile strength as they increase. The predictions of the given formulae are in good agreement with experimental data.