New Theoretical Analysis of the Splitting Process in the Square Metal Columns under the Axial Loading

During the splitting process, large deformation occurs in the structures and considerable energy dissipated by the system, and so it can use to design and manufacture the systems with the high energy absorbability. The objective of the present study is to further investigate the energy absorption involved in splitting a square tube under quasi-static loading. The metal tube was compressed axially between a rigid plate and a pyramidal die. Tubes were observed to have cracks propagating along the four corners. All four free end sides then rolled up into curls with a radius whose magnitude appeared to be mainly dictated by the semi-angle of the die. The applied load became constant after the initial peak load initiated the cracks. This mechanism results in a large stroke (above 90% of the tube length) and a constant load. Both of the split and curl can be designed for energy absorbing systems requiring large stroke to length ratio and good specific energy absorption. In this article, some theoretical relations are derived to predict the instantaneous axial load during the splitting in the square columns. For this purpose, it is assumed that the total energy is dissipated via four different mechanisms of deformation: bending, tearing, friction and expansion. These energy dissipating components are carefully assessed here. Based on the principle of conservation of energy, work of the external axial force is equated with the summation of the internal dissipated energy and the final relations are obtained. Comparison of the theoretical predictions by the presented equations with the experimental results of the other researchers shows a good correlation.

Keywords:

Axial load , Crack propagation , Energy absorption , Splitting , Square column