Hybridisation of AlSi10Mg lattice structures for engineered mechanical performance

As an evolution from foam structures, latticed structures have demonstrated incredible potential for fabricating components with tunable characteristics. Due to their high surface-to-volume ratio, triply periodic minimal surface (TPMS) lattice structures are promising for lightweight, high-strength structures. Recently, there has been growing attention in studying architected structures as their geometrical parameters can be tailored to control the performance both mechanically and thermally. These findings in the literature raised the attention that a combination of two or more lattice topologies can realise a more advanced performance. In the present work, we present an integrated numerical-experimental investigation into the performance of two surface-based lattice structures - AlSi10Mg primitive and Schoen's I-graph-wrapped package (I-WP), with different cell sizes and strut thicknesses manufactured by laser powder bed fusion (L-PBF). Quasi-static compression tests with digital image correlation were performed to evaluate their mechanical performance. Based on their respective response to loading, the two topologies were hybridized for a bespoke engineered mechanical performance. Finite element analysis was conducted based on data extracted from standard tensile tests on solid samples to develop a model that can be utilized to design a lattice with the desired performance. Microscopy and X-ray micro-computed tomography (XCT) were deployed to assess surface and internal defects in the printed lattices, which were then correlated to the failure mechanisms under loading. Despite observing a significant difference in the strength exhibited by the two designs, both behaved in a brittle manner. Hybridising the two distinctive designs into one lattice structure successfully yielded an intermediate mechanical behaviour, showing the approach as a good candidate for engineering failure modes in structural applications.