 This research examined thin-walled structures under dynamic loading conditions with an axial force. The structures were designed to act as passive energy absorbers through progressive harmonic crushing. The structures were made of AA-6063-T6 aluminum alloy and subjected to both numerical and experimental testing. Numerical analysis was conducted using Abacus software, while experimental testing was done on an Instron-9350 HES bench. The results showed that the number of holes and their diameters significantly affected the stroke efficiency indicator and mean crushing force. This article was offered by Michael Rogala and Jakub Gajewski.