The ply delamination which is known as a principle mode of failure of layered composites due to separation
along the interfaces of the layers is one of the main concerns in designing of composite material structures. In this paper
first the double cantilever beam (DCB) and three-point-end-notched flexure (3ENF) specimens were fabricated from
carbon/epoxy twill-weave fabrics and they were tested under quasi-static condition to determine the interlaminar
fracture toughness in Mode-I (GIC) and Mode-II (GIIC) of the selected lay-up. The cohesive zone modeling (CZM)
which is known as a variation in the cohesive stresses with the interfacial opening displacement along the localized
fracture process zone was used in ANSYS to predict the Mode-I and Mode-II delamination failure in laminated
composite structures. The numerical results were verified with the relevant experimental results