Energy absorption of thin-walled tubes enhanced by lattice structures

Thin-walled structures filled or covered by various materials have been proposed for energy absorption applications in recent years. At this point, additive manufacturing technologies provide an unprecedented opportunity to produce nontraditional low-density filler materials to further improve the energy absorption performance of thin-walled structures. With a similar motivation, novel hybrid structures, in which thin-walled tubes filled with periodic lattice materials, are proposed and the energy absorption behaviors of these structures are investigated under axial impact loading conditions. Two different types of lattice structures (i.e. body-centered cubic structure and body-centered cubic structure with vertical strut) are considered as filler materials, and the effects of number of lattice unit cell, diameter of lattice member and tube thickness on energy absorption characteristics of hybrid structures are examined using validated nonlinear finite element models. The results show that the tube and lattice structures contribute the buckling and bending resistance of each other during progressive deformation of hybrid structures, and a considerable enhancement in energy absorption performance could be achieved with appropriate selection of tube and filler lattice structure parameters. Particularly, the result revealed that the hybrid structures can absorb up to 115% higher impact energy compared with the sum of individual parts of hybrid structures. Besides, the hybrid structures also show promising performance in terms of crashworthiness parameters such as specific energy absorption and crash force efficiency, and thus these structures are recommended as potential candidates for crashworthiness applications.