In this paper, progressive crushing of prismatic multi-corner thin walled metal tubes under quasi-static axial load is investigated in detail. The novelty of the paper is mainly in considering strain hardening effect during plastic deformation instead of rigid plastic model and also the effect of curvature in forming the folds instead of plastic hinges. For this purpose, a new geometric model based on FEM and experimental observations is used which is capable of being adapted with new crushing configurations during crushing. Based on this model, the instantaneous energy associated with plastic deformation of different regions are calculated and finally by summing all energies and using minimum absorbed energy, mean crushing force and collapse parameters are determined. To evaluate the results, a detailed finite element study using ABAQUS and LS-Dyna solver is conducted on some regular polygonal mild steel tubes under axial crushing. Comparing the results of the new theoretical approach with FEM results show very good capability of that in predicting collapse behavior of these structures.
