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 c haracterize the transverse tensile response of fiber-reinforced compos ites. In the present study, extensive transverse tensile testing of si ngle and multiple-fiber specimens of SCS-6 SIC fiber/Ti-6Al-4V composi tes was performed. Poor consolidation and specimen damage prior to the lest, when present, caused the measured interface strength to be low. The debond stress was relatively insensitive to specimen thickness be tween 200 and 550 mu m. The average remote debond stress of well-conso lidated, damage-free specimens was 322 +/- 14 MPa, while a Weibull ana lysis indicated that the characteristic strength was 328 MPa and the W eibull modulus was 27. Stress analyses suggest that, at this level of remote stress, the interface supports a tensile stress of approximatel y 120 MPa, which is much greater strength than previously thought. Mul tiple-ply, multiple-fiber specimens were found to have nearly the same remote debond stress as the single-fiber specimens. Copyright (C) 199 7 Acta Metallurgica Inc. Inc.