Micromechanics of Interfaces in High Temperature Composites
Abstract
Both theoretical and experimental approaches have been used to examine the micromechanics of interfaces in ceramic-matrix, fiber-reinforced composites. In order to examine variables which allow for the optimization of fracture, toughness, analytical solutions first were developed to describe the stress displacement fields for a cylindrical inclusion adjoining a surface of an elastic half-space (equivalent to a single fiber intercepting a matrix crack). This same equivalent inclusion model was used to approximate multiple fibers spanning an internal crack. An energy approach was used to describe conditions of crack propagation and arrest in systems containing long fibers as a function of interface toughness, residual thermal stress, fiber size and concentration. Experimentally, the validity of fiber pullout tests was examined as means of acquiring accurate interfacial data. A new fiber pullout test was developed which best approximates matrix fracture, and fiber debonding and pullout in a full scale composite. Bridging forces by both on and off-axis fibers have been evaluated for a SiC/borosilicate composite, the latter providing the first experimental measures of bridging forces of inclined fibers. Finally, studies on fiber-reinforced cements have been conducted and compared to Mura's crack arrest theory with excellent agreement.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 30, 1992
- Accession Number
- ADA251736
Entities
People
- Katherine Faber
- Toshio Mura
Organizations
- Northwestern University