Assessment of the Additive Fabrication Quality of Sandwich Structures with Novel Triply Periodic Minimal Surface Cores

Abstract

Triply periodic minimal surface (TPMS) structures raised significant interest in several areas of research due to their unique properties and broad range of applications. The aim of the paper is to verify if such complex metamaterials can be fabricated effectively without defects that could compromise their mechanical response. An implicit modeling approach was used to generate eight novel TPMS structures and one stochastic topology. Multiple specimens were fabricated from a photopolymeric resin using a stereolithography (SLA) technique, and an analysis of the manufactured samples was carried out in terms of surface quality, dimensional and mass deviations, and internal porosity of the material. Laser scanning showed no significant deviations from the designed geometry but highlighted errors during the post-processing stages of manufacturing. Surface analysis resulted in an average roughness of 2.47 µm, a value specific to well-controlled additive manufacturing (AM) techniques. A microscopic examination portrays common types of defects, while an ultrasonic non-destructive inspection method showed no indication of defects in the depth of the samples. Sectioning the samples through water jet cutting exposed interior surfaces with better homogeneity than the exterior ones and the absence of a layer-by-layer aspect. Overall, the samples displayed no major defects and good accuracy, with minor inconsistencies and methods of mitigating them having been presented.