Characterisation of Manufacturability and Mechanical Response of Additively Manufactured Strut Elements and Lattice Structures

Abstract

Additive Manufacturing (AM) provides an opportunity for design innovation and sophisticated geometry compared to traditional manufacturing methods. More specifically, Metal Additive Manufacturing (MAM) using Laser-Based Powder Bed Fusion (LB-PBF) allows fabrication with various fusible metal alloys, including light alloys, superalloys, and tools steels. LB-PBF is suited to high-value engineered applications, including lattice structures for medical implants, aerospace components and custom tooling. However, the MAM process has inherent manufacturing defects such as porosity, dimensional accuracy, and surface texture, resulting in uncertainty of manufacturability and associated structural performance. Prior work in this field has focussed on either the geometric properties of strut elements or the mechanical response of entire lattice structures. This research proposes an individual systematic procedure to characterise and optimise the effect of manufacturing artefacts and defects on the structural response and efficiency associated with mechanical properties of AM strut elements. Furthermore, this understanding is expanded to allow insight into the effect of individual strut elements on the bulk lattice response. Essentially allowing the lattice structure to be considered as a population of unique strut elements rather than a single monolithic meta-material. This outcome is enabled by a novel, non-destructive digital-twin methodology developed within this research. The response of both individual strut elements and entire lattice structures were validated with experimental testing and analytical prediction, with the functional digital-twin method allowing insight into the contribution of individual strut elements on the bulk material response.