Experimental Comparison of the Energy Absorption Behaviors of the Triangular and Circular Tubes during the Flattening Process

This article investigates energy absorption behaviors of triangular and rounded tubes during the flattening process under the quasi-static lateral compression loading between two rigid platens by the experimental method. All the triangular tubes were produced by performing the elasto-forming process on the rounded tubes, using a V-shape die. Then, the triangular tubes and the corresponding rounded specimens were laterally compressed to study effects of cross-sectional shapes of two types of specimen on lateral load, energy absorption and specific absorbed energy. Also, some lateral compression tests were performed on the empty and polyethylene Teflon-filled triangular tubes to study effects of tube length, tube wall thickness and cylindrical Teflon-filler wall thickness. Load-displacement, energy–displacement and specific absorbed energy–displacement diagrams of each specimen were sketched to investigate the mentioned parameters. Experimental results show that in the flattening process, an empty triangular tube is a better energy absorber system, comparing with the corresponding rounded tube. Also, according to the experimental measurements, it is found that the triangular tubes with thicker wall have higher absorbed energy per unit of tube mass. Furthermore, in the Teflon-filled specimens, there is an optimum thickness for the cylindrical Teflon-filler and the optimized Teflon-filled triangular tube has the highest specific absorbed energy (SAE). Finally, the present article introduces a triangular tube with high tube wall thickness and the optim