The metal foam-filled tubes are one of the best energy-absorbing components in the field of crashworthiness, blast and impact protection due to their lightweight design and extraordinary energy absorption capabilities. The cores of foam-filled tubes can consist of different cellular or composite materials, providing different mechanical properties and deformation modes. Recent advances in additive manufacturing enable the fabrication of very complex and predesigned cellular geometries like Triply Periodical Minimal Surface (TPMS) structures.

The TPMS lattices were designed and generated using the software MSLattice. The generated cores, empty tubes and TPMS-filled tubes were fabricated using the powder bed fusion system EOS M280 with atomised stainless steel 316L powder. Five types of samples were considered in this work: as-fabricated empty tube, 3D printed empty tube, TPMS core, ex-situ TPMS-filled tube and in-situ TPMS-filled tube.

Compression and three-point bending tests under quasi-static and dynamic loading conditions were performed for all samples. The validated computational models provide a framework for further computational design of multi-morphology (hybrid) lattices with spatially variable cell types.

The results showed that the ex-situ and in-situ TPMS-filled tubes provide very similar responses, with a slightly stiffer elastic response of in-situ TPMS-filled tubes due to a better interface connection between the core and the tube. The specific energy absorption (SEA) of TPMS-filled tubes is increased up to 40 % at ex-situ TPMS-filled tubes and up to 46 % at in-situ TPMS-filled tubes if compared to the summed responses of core and empty tubes.

Under compression loading, the energy absorption of the axially loaded ex-situ and in-situ TPMS-filled structures is enhanced by 21 % and 44 % if compared to the as-fabricated empty tube, which has the highest SEA of empty tubes and the core. The SEA enhancement is much lower at transversal loading, where only the in-situ TPMS-filled tubes result in the SEA enhancement up to 12 %.