Crushing performance of auxetic tubes under quasi-static and impact loading

The aim of this paper is to investigate the energy absorption behavior of some reticulated tubes with different auxetic and non-auxetic wall grid patterns. Re-entrant, arrow-head and anti-tetrachiral were the three types of cellular patterns for auxetic reticulated tubes, and the conventional honeycomb pattern was used for the non-auxetic tubes. All of the designed specimens were fabricated by laser rotary cutting machine on steel tubes, and the crushing tests were performed by a universal testing machine and drop weight machine for quasi-static and impact loading rates, respectively. Also, the hollow reticulated tubes were filled with polyurethane foam to investigate the effect of filler on the crushing behavior of these novel tubes. Peak force, mean force, crushing force efficiency, total absorbed energy and specific absorbed energy were used as evaluating parameters. The results illustrate that the auxetic tubes showed a significant increase in SEA, CFE and EA parameters compared to non-auxetic conventional structures. Foam filling of the structures caused symmetric deformation and shows the benefit of auxetic pattern even in quasi-static loading. Also, a numerical analysis was carried out to simulate the experimental tests and a comprehensive discussion is performed, and based on the validation of the FE model versus the experimental crushing response the parametric study was conducted to understand further the effects of various loading rates.