EFFECTIVE CRACK-GROWTH AND RESIDUAL STRENGTH OF COMPOSITE LAMINATES WITH A SHARP NOTCH

The main objective of this study was to evaluate the residual strength of composite laminates with a sharp notch using an effective crack gr owth model (ECGM). Damage is assumed to initiate when the local normal stress ahead of the notch tip reaches the tensile strength of the unn otched laminate. The damage was modelled by a fictitious crack with co hesive stress acting on the crack surfaces and the damage growth was s imulated by extension of the fictitious crack and reduction of the coh esive stress with crack opening. The apparent fracture energy (G(c)) was used to define the relationship between the unnotched strength and the critical crack opening. Based on the global equilibrium condition , an iterative technique was developed to evaluate the applied load re quired to produce the damage growth. The residual strength of notched composite laminates was defined by the applied load instability with d amage growth. The effect of damage increment on the convergence of the residual strength was investigated and the stress redistribution with damage growth in the composite laminates was discussed. The residual strength simulated from the new model correlated well with experimenta l data in the published literature for the different laminate configur ations.