Delamination growth from face sheet seams in cross-ply titanium/graphite hybrid laminates

A test program was conducted to study the fatigue delamination behavior of titanium/graphite hybrid laminates (TiGr) with seams in the titanium face sheets. Tension fatigue experiments were conducted at −18°C, 21°C (room temperature), 93°C, and at 177°C on cross-ply, [Ti/0/90/02]s, titanium/graphite hybrid laminates (TiGr). The delamination growth rate obeyed a power-law function of the applied strain energy release rate range. The prefactor on the power-law function showed a strong dependence on temperature. In addition, experiments were performed on laminates with ±30° plies. The primary damage mode in this lay-up was edge delamination of the interior plies. Analysis of the [Ti/0/90/±θ]s family of laminates indicated that for angles greater than 10°, edge delamination would be the dominant damage mode in coupon specimens.