Dynamic enhancement of energy absorption capacities of heat-treated and additively manufactured thin-walled lattice-infill structures

Energy absorption capabilities are critical to the performance of structures in fast dynamic applications, such as crash and impact. This study experimentally investigated the influence of wall thickness on the compressive properties of a conventional body-centred cubic (BCC) lattice design. The structures were additively manufactured from aluminium alloy, AlSi10Mg, and heat-treated to increase ductility. Three wall thicknesses were investigated: 0.5 mm, 1.0 mm, and 1.5 mm, as well as no wall, with two relative densities for the BCC structure: 20% and 30%. This aimed to quantify their structural response in terms of apparent stress and strain, potential dynamic enhancement and specific energy absorption (SEA) capacities. The collapse mechanisms and plastic buckling wavelength of the deformed structures were examined, along with the effect of relative density, loading rate and heat treatment. It was found that the addition of the 0.5 mm wall increased the energy absorption qualities of the BCC structure for both relative densities. The lattice controlled the response mechanism similar to that of a bending-dominated structure. A dynamic enhancement was found for the BCC structure with 30% density and 1.0 mm wall thickness, with the lattice controlling the response mechanism under dynamic loading conditions. When considering an equivalent densification strain, the heat-treated and as-built structures with 0.5 mm wall thickness showed similar SEA and plateau stress responses for both relative densities. The findings of this study can be utilised to identify optimal wall thicknesses for various loading conditions in safety-critical impact applications. • Dynamic enhancement is found for 1.0 mm wall thickness and 30% infill density. • The 0.5 mm wall increases energy absorption with a bending-dominated response. • Similar specific energy absorption for heat-treated and as-built specimens at the same strain.