Mode I and Mode II Interlaminar Crack Growth Resistances of Ceramic Matrix Composites at Ambient Temperature

摘要

Interlaminar crack growth resistances were determined for five different SiC fiber-reinforced ceramic matrix composites (CMCs) including three gas-turbine grade melt-infiltrated SiC/SiC composites. Modes I and II crack growth resistances, GI and GII, were evaluated at ambient temperature using double cantilever beam and end notched flexure methods, respectively. The CMCs exhibited GI =200-500 J/m2 and GII=200-900 J/m2. Most of the CMCs, except the SiC/CAS composite, showed rising R-curve behavior either in Mode I or in Mode II, presumably attributed to fiber bridging (in Modes I and II) and frictional constraint (in Mode II) in the wake region of a propagating crack. A glass fiber-reinforced epoxy polymer matrix composite, used as comparison, showed R- curve behavior and typically 2-3 and 8 times greater in GI and GII, respectively, than the CMCs. Experimental error analysis concerning the effect of the off-the-center of a crack plane on GI and GII was also made.