A non-linear cohesive zone model is developed for predicting stress–strain behaviour of unnotched aluminium alloys. A uniform cohesive layer is added into the middle of a dogbone-type specimen. Mechanical properties of aluminium alloy 6082 are used as those of a cohesive layer; Voce equation is used for describing the softening behaviour of heat treated and non-heat treated plates. Damage state of a cohesive zone due to tensile loading is evaluated with the damage variable expressed as a function of strain. Predicted engineering stress–strain curves are directly compared with experimental ones. Results show that a proposed model provides the prediction of stress–strain behaviour of aluminium alloys.