Tensile Failure of Bio-inspired Lattices with Different Base Topologies

Abstract

In the last decades the use of cellular materials, either in the form of foams or lattices, has widely spread in engineering due to their specific properties, namely their high mechanical and multifunctional properties in terms of strength, stiffness, energy absorption, thermal and acoustic insulation at small weight compared to bulk materials. These features can be achieved, in the case of lattices, by designing their structure at different scales, both in two and three dimensions. Additionally, nowadays, complex desired geometries may be easily obtained thanks to consolidated and even recent technologies of production, especially Additive Manufacturing (AM) techniques. The aim of the present work is to investigate the mechanical behaviour exhibited by two-dimensional lattices with different types of engineered topologies under tensile loadings, focusing on damage evolution and eventual failure. Since past studies have shown, numerically and experimentally, the advantages of bio-inspiration from wood microstructures on honeycombs with hexagonal cells, in terms of crack deflection and therefore absorbed fracture energy, here also the performances of 2D lattices with different base topologies, namely triangular and triangular–hexagonal (aka "Kagome") cells, are evaluated. The comparison is based considering not only tensile tests on lattices with different base topologies, but also assessing, for each topology, the effect of lattice-density variations, ranging from sparse to variable density to fully dense lattices. The studies are carried out through Finite Element Analysis (FEA), using base material properties derived from curve fitting between experimental and numerical results on engineered specimens in ABS, 3D printed using Fused Filament Fabrication (FFF). Further theoretical, computational and experimental investigations are currently undergoing, towards a framework for lattice materials by design.