An improved two-arcs deformational theoretical model of the expansion tubes

Abstract

In this study, the theoretical model of the expansion metal tubes reported in [1] is improved by considering the die radius rdie. After the critical die radius rdie* decided by the tube radius-thickness ratio and the conical angle of die is introduced, the tube expansions are classified into three different deformation modes, according to the relation between actual die radius rdie and the critical die radius rdie*. The detailed theoretical studies of these models are given in order to extend the applicability of the proposed theoretical model.Compared with the relevant experimental and finite element results, it is validated that the current model gives a more accurate steady compressional force, within a wide range of parameters, i.e., the tube radius-thickness ratio ≥ 20, and the die conical angle α ≤ 40° Besides, the expanded tube radius could be accurately predicted, which is important in the metal tube forming. The energy absorption abilities of the expansion tubes are then optimized by taking the tube material properties and friction into consideration.