Evaluations of effective crack growth and residual strength of fibre-reinforced metal laminates with a sharp notch

The main objective of this study was to evaluate the residual strength of fibre-reinforced metal laminates with a sharp notch by means of an effective crack growth model (ECGM). Damage is assumed to be initiated when the local normal stress ahead of the notch tip reaches the tensile strength of the composite and the yield strength of metal layers, respectively. The damage in constituent materials was modelled by fictitious cracks with cohesive stress acting on the crack surfaces, and the damage growth was simulated by extension of the fictitious cracks and reduction of the cohesive stress with crack opening. The apparent fracture energy of composite layers and fracture toughness of metal layers was used to define the relationships between the tensile/yield strength and the critical crack opening. On the basis of global equilibrium, an iterative technique was developed to evaluate the applied load required to produce the damage growth. The residual strength of notched fibre-reinforced metal laminates was defined by instability of the applied load with damage growth. The effect of notch size on the residual strength evaluation was studied and the stress redistribution with damage growth was discussed. The residual strength simulated from ECGM correlated well with experimental data in the literature for the various ARALL laminates with a centre crack. The results indicate that stable crack growth occurs in both aluminium and composite layers before unstable fracture of the whole laminate.