The Mechanical Properties of Sandwich Structures Based on Metal Lattice Architectures

Abstract

A range of metallic lattice structures were manufactured using the selective laser melting (SLM) rapid prototyping technique. The lattices were based assemblies of repeating unit-cells with their strands oriented at 0°, ±45°, and 90° to the vertical when viewed from the front. Mechanical tests on the strands and the lattice blocks showed that these systems exhibit a high level of reproducibility in terms of their basic mechanical properties. An examination of the compression failure mechanisms showed that the [±45°] and [±45°, 90°] lattices failed in bending and stretching modes of failure, whereas the [0°, ±45°] lattices failed as a result of buckling of the vertical pillars. Sandwich structures were manufactured by binding woven carbon-fiber reinforced plastic to the lattice structures. Subsequent three-point bend tests on these structures identified the principal failure mechanisms under flexural loading conditions. Here, cell crushing, hinge rotation, and gross plastic deformation in the strands were observed directly under the point of loading. Low-velocity impact tests were conducted on the sandwich beams and a simple energy-balance model was used to understand how energy is absorbed by the sandwich structures. The model suggests that the majority of the incident energy of the projectile was absorbed in indentation effects, predominantly in the core material, directly under the steel indenter.

Fatigue behavior of IN718 microtrusses produced via additive manufacturing

“…When used in designs, this inhomogeneity must be dealt with conservatively, making the foamed metal less suitable for use in structures that require a high level of optimization [4]. The homogeneity of microlattice or microtruss designs offer an attractive alternative to the metal foams, while retaining or improving the characteristics that make cellular structures so desirable [5], especially for engineered sandwich structures [6][7][8].…”

Selective laser melting of aluminium components

“…SLM creates parts by scanning powdered materials with a laser beam so as to melt and fuse the material into a solid, the parts being manufactured layer by layer direct from the CAD file data. This process has produced some remarkable structures in a fairly wide range of materials, including titanium porous constructs for orthopaedic application (Mullen et al, 2009(Mullen et al, , 2010, and stainless steel lattice cores for sandwich structures (Shen et al, 2010). However, there have been a number of materials where processing has proved much more difficult, mainly because of the intrinsic metallurgy of the alloy systems.…”

The quasi-static and blast response of steel lattice structures

“…SEM images of lattice struts showing: (a) variation of strut diameter along its length[12] and (b) the circular cross-section.…”