Interlaminar Crack Growth Resistances of Various Ceramic Matrix Composites in Mode I and Mode II Loading

摘要

Interlaminar crack growth resistances were evaluated for five different SiC fiber-reinforced ceramic matrix composites (CMCs) including three gas-turbine grade melt-infiltrated SiC/SiC composites. Modes Ⅰ andⅡ crack growth resistances, G_Ⅰand G_Ⅱ were determined at ambient temperature using double cantilever beam and end notched flexure methods, respectively. The CMCs exhibited G_1=200-500 J/m~2 and G_Ⅱ=200-900 J/m~2. All the composites (except for one SiC/CAS composite) showed a rising R-curve behavior either in modeⅠor in modeⅡ, presumably attributed to fiber bridging (in modesⅠandⅡ) and frictional constraint (modeⅡ) in the wake region of a propagating crack. A glass fiber-reinforced epoxy polymer matrix composite showed typically two to three times greater G_Ⅰ and eight times greater G_Ⅱ, compared to the CMCs. An experimental error analysis regarding the effect of the off-the-center of a crack plane on G_Ⅰ and GⅡ was also made.