Understanding elastic anisotropy in diamond based lattice structures produced by laser powder bed fusion: Effect of manufacturing deviations

Abstract

Laser powder bed fusion (L-PBF) allows the production of metal lattice cellular structures with tailored mechanical properties. In order to generate the specific structural behavior it is of utmost importance to understand the response of the unit cells when different load conditions are considered. In this article the mechanical response of diamond based cellular structures has been investigated focusing on the impact of geometrical inaccuracy generated by the manufacturing process on the elastic anisotropy of the mentioned unit cell. The μ-CT analysis of the structures shows that the manufacturing deviations occur in certain orientations that depend highly on the building direction and proximity to nodes. The measured imperfection types were implemented in a finite element model in order to predict their single and combined effects in the elastic directional response. The results indicate that the L-PBF process can induce a significant change of elastic anisotropy in the diamond unit cells, including a substantial variation of the optimal orientation for minimal compliance. Methods are presented to calculate this anisotropy such that it can be taken into account when designing and using such lattice structures in real-life applications with multi-axial load conditions