Sg. Warrier et al., INTERFACE EFFECTS ON THE MICROMECHANICAL RESPONSE OF A TRANSVERSELY LOADED SINGLE-FIBER SCS-6 TI-6AL-4V COMPOSITE/, Metallurgical and materials transactions. A, Physical metallurgy andmaterials science, 27(7), 1996, pp. 2035-2043
The ability of a fiber-matrix interface to support a transverse load i
s typically evaluated in straight-sided composite specimens where a st
ress singularity exists at the free surface of the interface. This str
ess singularity is often the cause of crack initiation and debonding d
uring transverse loading. In order to develop a fundamental understand
ing of the transverse behavior of the fiber-matrix interface, it is ne
cessary to alter the crack initiation site from the free surface to an
internal location. To achieve this objective, a cross-shaped specimen
has been recently developed. In this study, based on the experimental
ly observed onset of nonlinearity in the stress-strain curve of these
specimens and finite element analysis, the bond strength of the SCS-6/
Ti-6Al-4V interface was determined to be 115 MPa. The micromechanical
behavior of these specimens under transverse loading was examined by f
inite element analysis using this interface bond strength value and co
mpared with experimental observations. Results demonstrate that the pr
oposed geometry was successful in suppressing debonding at the surface
and altering it to an internal event. The results from numerical anal
ysis correlated well with the experimental stress-strain curve and sev
eral simple analytical models. In an attempt to identify the true bond
strength and the interface failure criterion, the present study sugge
sts that if failure initiates under tensile radial stresses, then the
normal bond strength of the SCS-6/Ti 6Al-4V composites is about 115 MP
a; under shear failure, the tangential shear strength of the interface
is about 180 MPa.