A Model for Tensile Fracture of Carbon-Carbon Composite Fiber Bundles
JORTNER RESEARCH AND ENGINEERING INC COSTA MESA CA
Pagination or Media Count:
A probabilistic model for tensile fracture of straight-fiber carbon- carbon composites is proposed. The analysis derives from the extensive theoretical work available for graphiteepoxy composites but attempts to account for the weak microcracked interfaces in carbon-carbons by assuming load transfer between fiber and matrix is primarily frictional. The model extends the work of Chatterjee, et al, by including a predictive analysis for the frictional shear stress, incorporating a Poissons effect and a thermal-expansion effect. Inputs to the model include fiber, matrix, and interface properties including friction coefficient, fiber strength distribution or the length dependence of dry-yarn strength, and transverse stresses acting on the yarn bundle. Illustrative results show that composite strength may be expected to increase with temperature even if the fiber strength does not. Also, the results show that room-temperature strength of a carbon-carbon yarn tends to be significantly lower than the strength of a similar graphite-epoxy yarn, even if no degradation of fiber properties has occurred during the fabrication of the carbon-carbon composite.
- Refractory Fibers