In-Plane Quasi-Static Crushing Finite Element Analysis of Auxetic Lattices

Impact phenomenon is significant for our lives. It can be encountered in many fields. The critical areas are debris impact in space, bird striking on aircraft, ballistic and traffic accidents. For preventing the effect of impacts, some engineering structures are improved and used recently. These structures are used to absorb impact energy by avoiding the transfer of the high magnitude of the load which risks human life and essential part of vehicles that stems from the impact. For road vehicles, crush tubes are used for this purpose. However, they are not efficient, so that tube filling materials are used. Integration of filling materials to tubular systems shows a positive effect on the performance. However, in the case of impact, the impact load crushes the filling material, and filling materials expand laterally. This expansion pushes the boundary of tubular systems and causes bending moment in addition to the uniaxial compressive load at the tubular systems. Auxetic materials which expand laterally under tensile loads and shrink under compressive loads can prevent this incident. Auxetic materials exist in two forms. One of them is a foam form, and the other of them are lattices form. In this study, auxetic lattices are crushed with quasi-dynamic loads to determine their crush efficiencies. Re-entrant, anti-tetrachiral, chiral circular, chiral hexagonal auxetic structures are crushed with 10 mm/min velocity. Specific energy absorption (SEA) values are calculated for each other and compared.