Effect of cell size and wall thickness on the compression performance of triply periodic minimal surface based AlSi10Mg lattice structures

Abstract

Triply periodic minimal surface (TPMS) are mathematical surfaces with zero mean curvature and are spatially invariant. Recently, these surfaces are investigated for potential application in the manufacturing of cellular materials or lattice structures for a variety of purposes. However, designing such structures is a difficult task as the dedicated design platforms impose higher costs. Therefore, in this study, lattice structures have been designed using an in-house developed opensource tool for different cell sizes and cell wall thicknesses. The lattice structures have been additively manufactured through laser powder bed fusion (LPBF) and their design compliance and manufacturing defects have been investigated through optical micrography and SEM. The lattice structures have been subjected to quasistatic uniaxial compression test in as-manufactured and heat-treated conditions and the resulting compressive stress-strain curves have been analyzed in detail to draw a relationship between the two varying quantities and the mechanical properties of the lattice structure. The results show that there has been small but visible differences between the as-designed and as-manufactured lattice structures. The mechanical properties of lattice structures deteriorated with increasing cell size at constant wall thickness and improved with increasing cell wall thickness at constant unit cell size. The heat treatment procedures homogenized and increased plastic deformation while decreasing the strength and modulus values. Overall the study outlined a significant effect of cell geometry, size, and cell wall thickness on the mechanical properties of the TPMS lattice structures.