This research was undertaken as a contribution to the study of light weight ceramic materials. Specifically the relationship of bulk density and strength was investigated and an empirical equation for the type Y=aX^b, where Y represents unit crushing strength and X represents bulk specific gravity, was found to agree with the data. It was found that a rational theory for the strength of light weight ceramic materials is possible of attainment. / Master of Science

This dissertation culminates a three year research program investigating the properties and performance of a tubular, ceramic composite component. Eight test specimens were fabricated using an injection molding process with a borosilicate glass matrix reinforced with chopped graphite fibers. These specimens were then tested under quasi-static and cyclic loading at room temperature. Due to the infancy of CMC materials and, especially, CMC components, the program included a very broad-based investigation into many areas which are considered well-established for more conventional materials, and a very extensive and diverse set of achievements were realized. A tubular CMC test specimen representing an engineering component was designed and fabricated. A high temperature multiaxial test facility for ceramic matrix composite components was developed and installed at Virginia Tech. Nondestructive and destructive test methods for CMC components were developed, and a thorough investigation of the failure mechanisms in injection molded CMC tubes subjected to room temperature, quasi-static and cyclic loading was conducted in spite of a very limited quantity of material. As a result of this investigation, performance limiting defects in the injection molded tubes were identified. In addition, a generalized modeling approach was investigated for the analysis of complex, composite components which includes the effects of damage development under static and cyclic loading. All of these topics are discussed in detail in this dissertation. / Ph. D.