Energy absorption characteristics and deformation mechanism of TPMS and plate-lattice-filled thin aluminum tubes

In recent years, thin-walled structures filled with various materials and structures have been of interest due to their high energy absorption efficiency and lightweight. The current developments in additive manufacturing technologies provide a useful tool to produce low-density core materials to improve the energy absorption performance of thin-walled structures. For that purpose, lattice filled thin-walled structures with two types of periodic shellular materials (i.e., diamond TPMS and SC-FCC-BCC plate-lattice) were proposed, and the effect of various design parameters, including tube thickness and height, on the energy absorption characteristics was tested under quasi-static loading and validated using finite element analysis (FEA) and homogenization techniques. Diamond cylindrical core lattices developed diagonal shear bands at the early loading stages, while the constituting plates of SC-FCC-BCC lattice tended to bend toward the loading direction. As a result of their lower degree of buckling, short hybrid samples showed a higher ability to absorb energy as compared to long samples because of the larger induced interaction effect between the considered cores and tubes. These effects were due the variations in the deformation mechanism, which subsequently led to an increase in the energy absorption of the structures. From an energy absorption perspective, the optimal hybrid structure design with maximum specific energy absorption was found to be at 1 mm short hybrid tube samples for both SC-FCC-BCC plate-lattice (22.7 J/g) and diamond TPMS (18.6 J/g). This study demonstrates the potential of employing these structures in sectors where high energy absorption is necessary, including automotive, aerospace, and protective structures and are, thus, recommended as promising candidates for crashworthiness applications.