A new theoretical analysis for the splitting of square columns subjected to axial loading

In this article, some theoretical relations are derived to predict instantaneous axial load during the splitting process of square columns on rigid pyramidal dies. For this purpose, it is assumed that kinetic energy is dissipated by four dierent deformation mechanisms: bending, friction, crack propagation and expansion. These mechanisms are carefully assessed. Based on the principle of energy conservation, the external work of axial force is equated with total dissipated energies during the plastic deformation, and nal relations are obtained to predict the load-displacement diagram. Also, the curl radius of square columns during the splitting process is calculated theoretically. Then, some metal tubes are tested and compressed axially between a rigid plate and a pyramidal die. Cracks propagate along four corners of the column. Experiments show that all four free end sides roll up into curls with a constant radius, and applied load becomes constant after crack propagation. This mechanism results in a large stroke and a constant load. Therefore, splitting is introduced as an energy absorber mechanism with large stroke to length ratio and high specic absorbed energy. Comparison of the theoretical predictions by derived equations, with the experimental results, shows good correlation.