In many engineering structures, especially transportation systems, energy-absorbing structures are used to prevent or reduce collision damage. Thin wall structures are an important category of these systems. The present study investigates the level of energy absorption and crushing behavior of thin-walled aluminum structures with multi-cell square sections under lateral impact loading. The material used to produce the samples is AL-6061. The samples were subjected to lateral impact loading by combining different wall thicknesses to determine the optimal cross-section geometry. For this purpose, numerical simulation was conducted using Abaqus software. Firstly, the simulation method was validated, and after validation, different combinations of multi-cell square sections with varying wall thicknesses were designed using the Design of Experiment (DOE) method. Additionally, due to the assumption of thin walls in the structures, the wall thicknesses of the samples were considered in the range of 1 to 3 mm. The mass and initial velocity of the impactor are 35.7 kg and 6.26 m/s, respectively. The results showed that the wall thickness of the structures and their different combinations can have a significant effect on their energy absorption parameters. These effects are generally nonlinear, with severe effects observed in some cases. Finally, through the analysis of the energy absorption process of the structures and the use of the response surface method (RSM), an optimal sample was designed and simulated. The results indicate an increase of approximately 246% in the specific energy absorption of the optimal sample compared to the sample with the same wall thickness.
