Development of simplified finite element models for straight thin-walled tubes with octagonal cross section

In this paper, simplified finite element models for straight thin-walled tubes with octagonal cross sections are created and validated through crashworthiness analyses. To create the simplified models, the collapse characteristics of thin-walled octagonal tubes under axial compression are derived and their axial crushing resistance is derived applying global energy equilibrium theory. The derived axial resistance is then applied for creating nonlinear spring elements that can properly predict the buckling behavior of the thin-walled octagonal tube model. Simplified thin-walled octagonal tube models are developed by using the beam element and the new nonlinear spring element and following certain modeling methods. Both detailed and simplified models are used for crashworthiness analyses and the results are recorded and compared. Relatively good agreement is achieved between these analyses, while both computing time and modeling time arc significantly reduced for the presented simplified models.