<p>Accurate prediction of the mechanical response of aluminum alloys under complex stress states is essential for reliable forming and structural simulations. In this study, the mechanical behavior of AA5754-O aluminum alloy is investigated through a combination of experimental testing and finite element modeling. Uniaxial tensile, plane strain, and shear tests were conducted along the rolling direction to characterize stress–strain responses under different stress states. The experimental data were used to calibrate isotropic hardening models based on the Swift and Voce formulations and to evaluate the predictive capability of pressure-insensitive and pressure-sensitive yield functions, namely the von Mises and pDrucker models. Finite element simulations were performed to reproduce the experimental load–displacement responses and to assess model accuracy. The results show that the pDrucker yield function provides improved agreement with experimental data under plane strain loading, while both yield functions exhibit comparable performance in uniaxial tension and shear. The Swift-Voce hardening law offers a robust description of strain hardening behavior across the investigated stress states. The findings highlight the importance of considering stress-state sensitivity in yield modeling and provide practical guidance for selecting constitutive models in simulations of aluminum alloy forming and deformation processes.</p>