Evaluation of Stress Redistribution and Notch Sensitivity in Ceramic Matrix Composites (CMCs)

Damage tolerance, which depends upon inelastic mechanisms, is crucial to the general utility of ceramic matrix composites (CMCs). Recent experiments have confirmed several damage mechanisms and revealed that stress redistribution does occur in CMCs. The current composite paradigm relies on fiber coatings to achieve this damage tolerance. More recently, an Al2O3/ Al2O3 CMC was developed which attains damage tolerance through the use of a porous matrix. To evaluate this all-oxide material, tensile experiments were conducted on double edge-notched test specimens. An infrared imaging technique, known as thermoelastic stress analysis, was used to classify the damage mechanism and measure the extent of stress redistribution in double edge-notched specimens. Results indicate that the subject alumina/alumina composite exhibits a measurable degree of ductility by developing shear band damage zones.