| Theoretical models are being developed to predict the fracture modes and the failure mechanisms of ceramic matrix composites (CMCs). These models require knowledge of the composite constituent properties including fiber and matrix strength, interfacial sliding stress, statistics of fiber fracture, etc. Mechanical tests have been conducted on several composite systems to determine both the mode of failure and the notch sensitivity of the composites. The constituent properties of several ceramic fiber-reinforced ceramic matrix composites are determined by experiment or found in literature, thus providing a knowledge base for the development of the damage and fracture models. The mechanical tests results are compared to values predicted by the theoretical models. Preliminary results indicate that matrix cracking and fiber pullout play an important role in the stress redistribution. The goal of the research is to predict how the materials will behave when used as structural components. Proposed experiments include various loading techniques and specimen geometries, including double edge notch tensile tests, tensile shear, Iosipescu, pin loading, and fatigue tests. The results will be used to develop a model that can predict the failure characteristics for different geometries and loading conditions. |
