This study attempted to examined the energy absorption and the mechanical behavior of thin-walled aluminum structures with square section, which are connected to the structural wall by either internal or external stiffeners and then exposed to axial quasi-static loading. The features of energy absorption examined in these structures included specific energy absorption, mean crush force, initial maximum force, deformation style and returns to crush force efficiency. The impact of stiffener layout on energy absorption was evaluated through several primary simulations through LS-DYNA for hypothetical models. Finally, a few different samples of the primary models were developed and tested experimentally. In experimental studies after annealing and determining the mechanical properties of aluminum 1100, the energy absorption properties under quasi-static pressure were found. The results of numerical and experimental studies showed good consistency. The results showed that the specific energy absorption of square thin-walled structures enhances as the number of stiffeners increases, which depends on the position of the stiffeners. The experimental tests proved that the layout of stiffeners according to the proposed model can increase specific energy absorption (SEA) by up to 65% compared to samples without stiffeners. Moreover, the crush force efficiency (CFE) during the test amounted desirably to 0.69.
