Simplified Modeling of Thin-Walled Tubes with Octagonal Cross Section – Axial Crushing

This article investigates the collapse characteristics of thin-walled tubes with octagonal cross sections during axial crushing. The tubes’ axial crushing resistance (the relationship between crushing force and axial deformation) is described with a series of mathematical equations, which are derived applying global energy equilibrium theory. The derived axial crushing resistance is then used for developing simplified finite element models for the thin-walled octagonal tubes. The simplified finite element model is composed of beam elements and nonlinear springs, where the nonlinear springs were defined using the derived axial resistance and would be used to simulate the buckling behavior of the simplified model during crash analyses. The developed simplified models are used for crash analyses, and the results are compared to those from corresponding detailed models as well as from the published literatures. Relatively good agreement is achieved through these comparisons, and it shows that the simplified models can save much more computer resources and modeling labor compared to the detailed models. Explicit code LS-DYNA is used for all the modeling and simulation presented in this article.