Effect of atomic tessellations on structural and functional properties of additive manufactured lattice structures

Abstract

The properties of lattice structure are influenced by cell morphology, cell size, relative density and tessellations. In this study, the concept of tessellation has been evaluated for structural and functional properties of additively manufactured lattice structures using PA-12 material. The tessellation design of unit lattice cell is inspired by arrangement of atoms in crystal structures. The strategy of mimicking these different arrangements at atomic level to generate mesoscale cellular structures is termed as ‘Atomic Tessellation’. In the current study, arrangement of metallic crystal structures: BCC, FCC and HCP were compared with conventional periodically tessellated SC structure using sea-urchin unit cell for mechanical, energy absorption and structural behaviour properties. The tessellated lattice structures were printed with hybrid AM technology using HP-MJF 4200. The significant effect of tessellations was observed during compression testing of printed samples in terms of their stress-strain behaviour. Lattice structures such as SC, BCC, FCC and HCP_90 shows ‘degradation-prone deformation behaviour’ which is similar to stretch dominated behaviour in structural elements (thin struts and thin walls). On the other hand, HCP tessellation (HCP_0) converts ‘degradation-prone deformation behaviour’ into ‘progressive deformation behaviour’ that is similar to bending dominated behaviour in structural elements. Moreover, significant effects of tessellations were also observed in load bearing and energy absorption properties. Although the study has attempted to introduce the design concept of atomic tessellations from structural point of view, further studies are required to strengthen tessellation based design principles for obtaining different structural and functional properties. • The novel concept of ‘Atomic Tessellation’ have been introduced in design of cellular lattice structures. • Metallic crystal structures: SC, BCC, FCC and HCP were designed in mesoscale using Sea Urchin (SU) inspired unit cell. • Mechanical properties and energy absorption capacity was affected by tessellation strategy. • Tessellation strategy converts stretch-dominated behavior of lattice structure to bending dominated behavior and vice versa. • HCP tessellated structure behaves as bending dominated in 0˚orientation whereas as stretch dominated behavior was observed in 90˚orientation.