Fatigue delamination initiation in L-bend CFRP coupons

Accurate modelling of the delamination of composites due to cyclic loading is important to reduce the costs associated with fatigue testing of structures. This work aims to identify the point of damage initiation in a carbon-fibre laminate subject to pure interlaminar tensile cyclic loading for a range of severities and stress ratios, in order to generate full SN-curves for an aerospace-grade carbon-fibre epoxy composite. Curved beams have been used in 4-point bend tests roughly in line with the ASTM D 6415 test standard to generate the required failure conditions. The tests were monitored in-situ using an Acoustic Emissions system and post-test CT (X-Ray) Scans were employed to identify failure conditions in the specimens.