Nanostructure-based finite element analyses of aluminium profiles subjected to quasi-static axial crushing

In this study, a nanostructure model is used to predict the stress-strain curves of the aluminium alloys AA6063, AA6061 and AA6110 in T6, T7 and O tempers based on the chemical composition and the thermo-mechanical history. The predicted stress-strain curves are then employed in finite element analyses of rectangular hollow section (RHS) profiles of the same materials subjected to axial quasi-static crushing. Thus, the simulations are performed without any calibration of the plasticity model based on material tests. In addition, simulations with the material model calibrated from tensile tests on the same materials are performed for comparison. An experimental programme of the RHS profiles is conducted for validation purposes and compared to the numerical results in terms of the force-displacement curves and the peak and mean forces. To put emphasis on the performance of the nanostructure model, a refined solid element model is used to capture accurately the deformed geometry during axial crushing. A separate study is conducted to investigate the effect of friction on the simulated behaviour of the profiles. The numerical and experimental force-displacement curves display good agreement with deviations in the mean absolute percentage error (MAPE) of the peak and mean force less than 10% and 8%, respectively. By visual inspection of the deformed profiles, excellent agreement is found between the numerical simulations and the experimental tests. The results suggest that the nanostructure model can be used with confidence in design of energy absorbing structural components made of 6xxx aluminium alloys.