Damage mechanisms and failure modes in cross-ply laminates under monotonic tensile loading: The influence of fiber sizing

The effect of fiber-matrix interphase on the damage modes and failure mechanisms in (0, 90 sub(3)), cross-ply graphite-toughened epoxy laminates is investigated. To study the effect of interphase, two material systems (designated as 810 A and 810 O) with the same fiber and same matrix, but with different fiber sizings were used. Results indicate that the fiber-matrix bond strength is lower in the 810 O system compared to the 810 A system. Transverse matrix cracking initiates at a significantly lower stress level in the 810 O laminate. The 810 O laminates also exhibit longitudinal splitting, while the stronger bonding suppress this damage mode in the 810 A laminates.