Mode I and Mode II Interlaminar Crack Growth Resistances of Ceramic Matrix Composites at Ambient Temperature
NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
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Interlaminar crack growth resistances were determined for five different SiC fiber-reinforced ceramic matrix composites CMCs including three gas-turbine grade melt-infiltrated SiCSiC 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 Jm2 and GII200-900 Jm2. Most of the CMCs, except the SiCCAS 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.
- Ceramics, Refractories and Glass