Continuous graded Gyroid cellular structures fabricated by selective laser melting: Design, manufacturing and mechanical properties

Abstract

Functional graded cellular materials (FGCMs) have attracted increasing attentions for their improved properties when compared to uniform cellular structures. In this work, graded Gyroid cellular structures (GCSs) with varying gradient directions were designed and manufactured via selective laser melting (SLM). As a reference, uniform structures were also manufactured. The surface morphology and mechanical response of these structures under compressive loads were investigated. Results indicate high manufacturability and repeatability of GCSs manufactured by SLM. Optimized density distribution gives these structures novel deformation and mechanical properties. GCSs with density gradient perpendicular to the loading direction exhibit deformation behaviours similar to uniform ones, while GCSs with the gradient parallel to the loading direction exhibit layer-by-layer deformation and collapse behaviour. A novel phenomenon of sub-layer collapses is found in GCSs with gradient parallel to the loading direction. Furthermore, mathematical models were developed to predict and customize the mechanical properties of graded cellular structures by optimizing the relative density of each layer. These significant findings illustrate that graded cellular structures have high application prospect in various industries, particularly given the fact that additive manufacturing has been an enabler of cellular structure fabrication. Keywords: Graded cellular structure, Selective laser melting, Energy absorption, Compressive response, Triply periodic minimal surface