ROOM TEMPERATURE POST-FRACTURE TENSILE (PFT) STUDY OF TWO FIBER-REINFORCED CERAMIC MATRIX COMPOSITES WITH A 'STRONG' FIBER/MATRIX INTERFACE

摘要

Room temperature fiber pullout under monotonic and cyclic loading was successfully investigated by using the PFT test configuration. Static (monotonic) PFT test led to the identification of a common strain-softening exponent between PFT speci-rnmens. This suggests the existence of a displacement-controlled failure mechanism for this new type of fiber-reinforced ceramic matrix composites with a strong fiber/ matrix interface. An inversely proportional maximum bridging stress with respect to COD was found for both composites. Gross slip under cyclic loading was observed for both composites, suggesting a reduced number of contact points due to interfacial wear. However, the stochastic behavior of the hysteresis loops during long-term fatigue experiments suggested a reconfiguration of the fiber/matrix interacting surface after gross slip. In addition, SEM analysis led to the identification of different pullout mechanisms between composites. The data suggests bundle pullout is a more severe pullout mode.