Role of multi-layer pyramidal truss cores as an inner material of energy absorbing structures

In this study, finite element analysis was performed to investigate the feasibility of multi-layered pyramidal truss structures as a filler material of energy absorbing tubes. Rectangular tubes with the filler and empty tubes were compressed at a constant velocity of 10km/h and their energy absorbing capabilities were compared to demonstrate the structural benefit of filling materials in the tubes. Additionally, the compressive response of the multi-layered pyramidal truss structures without tube wall constraint were observed. The investigations included three tube wall thicknesses and three pyramidal truss structures with three relative densities by varying the inclination angle of the pyramidal truss strut. Those were made of Al6063T5 and 304 stainless steel (SS304) for tube wall and pyramidal truss structure, respectively. The results indicate that the energy absorption capability of the tube with the filling exceeds the simple sum of that of tube and that of the filler, and this is due to the interaction effect between outer tubes and pyramidal truss struts near the tube wall. Furthermore, the inclination angle of pyramidal truss struts influences energy absorption. Thus, the pyramidal truss structures can be potentially applied as a filler material for energy absorbing structures.