Mechanical Properties and Failure Behaviour of Architected Alumina Microlattices Fabricated by Stereolithography 3d Printing

Abstract

The mechanical behaviour of Simple Cubic, Octet Truss and Kelvin Cell alumina microlattices with solid struts was systematically studied through experiments and simulations. Our results showed that the specific mechanical properties of the microlattices were the best for Simple Cubic, worst for Kelvin Cell, and followed Ashby’s power law well at small relative densities (≤ 0.3). At higher relative densities, the power law changed as joint deformation became increasingly important to overall lattice mechanics. The Simple Cubic lattices failed in a column-by-column manner from the sides inwards to the centre, while fracture in Octet Truss and Kelvin Cell lattices took place predominantly along the diagonal (110) plane. This was confirmed to be due to the interplay between the fixed top and bottom boundaries with the free sides of the lattices. At low relative densities, the microlattice struts were also observed to fail in a sequential, localized manner, in contrast to the simultaneous fracture observed at higher relative densities. Compared to current materials, the alumina microlattices exhibited outstanding specific moduli and specific strength, as well as limited ductility in the form of pseudoplastic strains (0.1% - 0.5%). Therefore, alumina microlattices are expected to be an invaluable addition to the material catalogue for engineering designers.