Mode i interlaminar fracture characterization of CFRP composite laminates

Abstract

This study examines the deformation response of CFRP composites with preexisting delamination crack under Mode I loading. A DCB specimen is used in a series of Mode I interlaminar tests, each having a different initial delamination crack length. The 48-ply composite laminate has a symmetric ply sequence with 0/0 fiber orientation at the mid-plane. Apparent toughness is indicated by the composite specimen with a starter film insert, likely due to the presence of a neat pocket of resin at the front of the starter crack. The compliance of pre-delamination cracked specimens increases faster beyond the normalized delamination length, a/L of 0.68 due to effects of severe deflection of the longer DCB specimen arm. The critical energy release rate, GIC = 0.5 N/mm is determined based on pre-cracked DCB specimens. Fractographic analysis revealed a smooth fracture plane that indicates interface delamination as the primary failure mode.