3D printed three-dimensional metallic microlattices with controlled and tunable mechanical properties

Abstract

Abstract Three-dimensional metallic microlattice structures are critical for advancements in areas such as energy storage and conversion, high-sensitivity sensors, light-weight structures, bone implants, and high-efficiency catalysts. In this paper, Aerosol Jet 3D nanoparticle printing (Saleh et al., 2017) [23] is utilized to fabricate novel highly complex three dimensional (3D) metallic microlattice materials having near-solid truss members with diameters of 30–60 µm and unit sizes of 100–400 µm. Three types of lattice structures having densities from 5% to 26% of the bulk metal are designed to deform via bending-dominated and buckling-dominated mechanisms under compressive loads. The mechanical response of these microlattices could be tuned by changing the structure density as well as making simple changes to the cell architecture. It is shown that AM related local defects in the 3D structures did not significantly influence their global stress-strain response. A modified semi-empirical foam deformation model is proposed to capture the oscillating hardening and softening mechanical behavior of ordered structures in the plateau stress region and is fit to all three lattice structures printed in this study. Finite Element Analysis (FEA) of the deformation using 3D beam elements was also performed, which showed an agreement with the experimental observations for both the global stress-strain response and the local deformation for structures that deform by bending. A theoretical model of general applicability is also proposed that captures the periodic hardening and softening behavior of the microlattice structures in the plateau region of their stress-strain plots. The research results establish that AJ printing can be used to fabricate a novel class of microlattice structures with tunable and controlled mechanical response.