The interface debond stress in single and multiple SiC fiber/Ti-6Al-4V composites under transverse tension

The cruciform specimen, which effectively eliminates the influence of the fiber-free surface intersection, has recently been introduced to characterize the transverse tensile response of fiber-reinforced composites. In the present study, extensive transverse tensile testing of single and multiple-fiber specimens of SCS-6 SiC fiber/Ti-6Al-4V composites was performed. Poor consolidation and specimen damage prior to the test, when present, caused the measured interface strength to be low. The debond stress was relatively insensitive to specimen thickness between 200 and 550 μm. The average remote debond stress of well-consolidated, damage-free specimens was 322 ± 14 MPa, while a Weibull analysis indicated that the characteristic strength was 328 MPa and the Weibull modulus was 27. Stress analyses suggest that, at this level of remote stress, the interface supports a tensile stress of approximately 120 MPa, which is much greater strength than previously thought. Multiple-ply, multiple-fiber specimens were found to have nearly the same remote debond stress as the single-fiber specimens.