A theoretical study of the expansion metal tubes
Abstract
A theoretical model is proposed to analyze the expansion of metal tubes over a conical mandrel die, based on energy conservation. Unlike previous momentum-based analyses, this model considers that the external compressive work is dissipated through circumferential expansion, meridional bending, and friction during steady-state deformation. Predictions are provided for steady compression force and expanded tube radius for rigid–perfectly-plastic materials, with and without strain hardening. Comparisons with experimental data and finite element simulations show that the model accurately predicts steady compression force and expanded radius. These results highlight the advantages of expansion tubes—long stroke, stable reaction force, and low sensitivity to inclined loading—making them suitable for energy absorption applications.
