Residual Strength Simulation of Fibre Reinforced Metal Laminates Containing a Circular Hole

The main objective of this study was to evaluate the residual strength of fibre reinforced metal laminates (FRMLs) with a circular hole using an effective crack growth model (ECGM). Damage is assumed to initiate when the local normal stress at the hole edge reaches the tensile strength or yield strength of composite and 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. Based on the 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 hole size on the residual strength was studied and the stress redistribution with damage growth was discussed. The residual strength simulated from ECGM correlated well with experimental data in the open literature for various ARALL laminates with a circular hole. The results indicate that damage first occurs in the composite layer, followed with stable crack growth well before ultimate failure, associated with plastic yielding of metal layer at the hole edge.