Experimental and numerical response in sls-manufactured polyamide-12 octet-truss lattice under tension and compression

Abstract

Abstract Additively manufactured lattice structures, particularly stretch-dominated topologies such as the octet-truss, offer exceptional stiffness-to-weight ratios. However, significant discrepancies often arise between numerical predictions based on as-designed geometries and corresponding experimental responses. This study presents a comprehensive mechanical characterization of octet-truss lattice structure made of Selective Laser Sintering fabricated Polyamid-12 under both tensile and compressive loadings. Two different plasticity material models are considered for the calibration of the material models in FEM simulations. Material plastic data for Von Mises model and parameters for Drucker-Prager model are presented. Optic and Environmental Scanning Electronic Microscope images of the fractured surfaces of the specimens are presented. Morphology of the fractured surfaces revealed whitened regions with fibrillation indicating ductile failure and darker regions with intra/interlayer failure modes and spherulites indicating brittle failure. Drucker-Prager plastic hardening model with nominal strut diameter exhibited a good approximation of the compressive lattice specimens and captured the experimental elastic, plastic and densification regions, especially for the specimen with a layer-by-layer failure. The overestimated numerical result of the tensile lattice specimen is attributed to the manufacturing error, unsintered layer and the porosity, and modified by the effective diameter of the struts. The study establishes a quantitative link between manufacturing-induced variability and mechanical behavior, providing a predictive framework for more reliable design of high-performance lattice metamaterials.