The Effects of Local Buckling on the Crash Energy Absorption of Thin-walled Expansion Tubes

Abstract

This paper deals with the local buckling characteristics and the energy absorption of thinwalled expansion tubes during tube flaring processes. The local buckling load and the absorbed energy during the flaring process were calculated for various types of tubes and punch shapes by finite element analysis. The energy absorption capacity of the expansion tube is influenced by tubes and punch shapes. The parametric study shows that the absorbed energy of the expansion tube increases as the diameter and the wall thickness of tubes increase. Larger punch angle and expansion ratio also improve the energy absorption. However, local buckling takes place relatively easily at larger punch angle and expansion ratio. Local buckling loads are also influenced by both the tube radius and thickness. Accurate prediction of the local buckling load is important to improve the energy absorption of the expansion tube since the absorbed energy of an expansion tube decreases significantly when local buckling occurs. Local buckling loads were predicted by modification of the Plantema equation and compared with numerical results. A modified Plantema equation shows a good agreement with the numerical result.