Additively manufactured AlSi10Mg inherently stable thin and thick-walled lattice with negative Poisson’s ratio

Abstract

Literature on the mechanical performance of additively manufactured (AM) negative Poisson’s ratio (−ν) structures has been primarily focused on beam-based re-entrant structures with chevron crosslinks. The walled variants of this architecture have been shown to exhibit lateral instability. This is where a layered framework can be advantageous as they provide increased lateral stability. Much less is known regarding the behaviour of such architecture, let alone their thin/thick-walled variants. This study explores the influence of design parameters namely wall thickness (t) and angle (θ) on the mechanical performance of thin and thick-walled inherently stable −ν lattices. The design is achieved through conceiving linearly arranged AlSi10Mg re-entrant unit-cells while discarding the traditional chevron crosslinks. The printed prototypes were experimentally tested and response surface (RS) models were generated to study the parametric influence on the elastic modulus (E), compressive strength (σc), failure strain (εf), − ν and relative density (ρr). The results demonstrate that both thin- and thick-walled structures exhibit ν of -0.108 to -0.257 despite the interaction effects between t and θ. The elastic modulus can be increased by either increasing t or θ without considering the interaction effects at 0.3 ≤ t ≤ 1 mm and 45° ≤ θ ≤ 85°. This study presents a new understanding regarding the fabrication and performance of re-entrant structures by AM.