Truss and plate hybrid lattice structures: Simulation and experimental investigations of isotropy, large-strain deformation, and mechanisms

In this study, we propose a novel class of crystal structure mimicking truss and plate hybrid lattice structures as isotropic lightweight structural and energy-absorbing material. Among the various structures, the combination of an octet truss and a plate (OT-P) constitutes the best elastic isotropy. Our design is experimentally validated using samples fabricated via micro-selective laser melting using 316L stainless steel as the base material. To validate its isotropy, the structural properties in three directions: [100], [110], and [111], are studied. High build qualities, with low Ra roughness ranging from 2.1 to 21 & mu;m, at a strut diameter of 500 & mu;m, have been observed. Compression tests reveal excellent elastic isotropy, with a Young's modulus ranging from 8.3 to 8.8 GPa in these three directions. The large-strain properties indicated high isotropy in the compressive strength (54 - 64 MPa) and specific energy absorption (SEA) (16.3 - 18.3 J/g). The high strength attributes to the plate members being aligned in the direction of compression. The high SEA in turn attributes to the stable, layer-by-layer deformation without abrupt stress-strain valleys. Overall, we have demonstrated the potential of hybrid truss and plate lattice structures as advanced lightweight structural materials.