Lattice structures are a prime candidate for applications in the medical implant industry due to their versatile mechanical behaviour, which can be tailored to meet specific patient needs and reduce stress shielding, while enabling the natural flow of body fluids. In this work, the mechanical properties of metallic lattices made of five different unit cell types, Cubic (C), Truncated Octahedron (TO), Truncated Cubic (TC), Rhombicuboctahedron (RCO), and Rhombitruncated Cuboctahedron (RTCO), were evaluated under uniaxial compression at three different relative densities, 5%, 15%, and 45%. The evaluation was experimental, and it was compared with previous and new finite element simulations. Specimens for the experimental tests were fabricated in stainless steel 316L by laser powder bed fusion, and stress–strain curves were obtained for the different lattices. The combination of the test results with a critical interpretation of the deformation mechanisms allowed us to confirm that two unit cell types, TO and RTCO, are stable for the whole range of relative densities evaluated. The other three unit cells exhibit more unpredictable behaviour, either due to manufacturing defects or limitations, or because their unstable compression behaviour leads to bucking. For these reasons, TO and RTCO unit cell types are mechanically more adequate for applications in the medical implant industry.

Laser powder bed fusion (L-PBF) is one of the most promising additive manufacturing technologies for creating customised 316L Stainless Steel (SS) implants with biomimetic characteristics, controlled porosity, and optimal structural and functional properties. However, the behaviour of as-fabricated 3D 316L SS structures without any surface finishing in environments that simulate body fluids remains largely unknown. To address this knowledge gap, the present study investigates the surface characteristics, the internal porosity, the corrosion in simulated body fluid (SBF), and the mechanical properties of as-fabricated 316L SS structures manufactured by L-PBF with rhombitruncated cuboctahedron (RTCO) unit cells with two distinct relative densities (10 and 35%). The microstructural analysis confirmed that the RTCO structure has a pure austenitic phase with a roughness of ~20 µm and a fine cellular morphology. The micro-CT revealed the presence of keyholes and a lack of fusion pores in both RTCO structures. Despite the difference in the internal porosity, the mechanical properties of both structures remain within the range of bone tissue and in line with the Gibson and Ashby model. Additionally, the as-fabricated RTCO structures demonstrated passive corrosion behaviour in the SBF solution. Thus, as-fabricated porous structures are promising biomaterials for implants due to their suitable surface roughness, mechanical properties, and corrosion resistance, facilitating bone tissue growth.

Additive manufacturing, particularly using Laser Powder Bed Fusion (LPBF) technologies with 316L stainless steel, has proven highly promising in biomedical engineering due to the material’s exceptional mechanical properties and biocompatibility. This study, which is a foundational step towards developing porous bone implants, focuses on assessing the influence of a broad range of parameters - spot size, scanning speed, laser power, and energy density - on the mechanical performance and structural integrity of 316L stainless steel parts across three distinct specimen geometries: fully dense parallelepipedic, fully dense cubic, and cellular (lattice) specimens. By analysing 17 different parameter sets and producing over 150 specimens, a thorough series of experimental tests were conducted, including flexural tests, compression tests, hardness tests, macroscopic evaluation of the surface of fully dense specimens, and macroscopic evaluation of the lattice structures.e in powder accumulation within the pores of cellular structures, with higher energy densities (100 J/mm ³ ) leading to a significantly greater retention compared to lower energy densities (66 J/mm ³ ). This underexplored phenomenon has significant implications for the selection of parameters in the fabrication of bone implants. Further research is needed to refine LPBF printing parameters and enhance the quality of porous bone implants.

In the evolving landscape of power transformers, the integration of advanced technologies, such as high-performance polymers obtained by Fused Filament Fabrication (FFF), is crucial. This study investigates the compatibility and performance of various 3D-printed polymer materials—Biofila, polyvinylidene fluoride (PVDF), polyphenylene Sulfone (PPSU), polyetheretherketone (PEEK), polyetherimide (ULTEM 1010), and polyetheretherketone reinforced with 20% glass fiber (PEEK-GF20) for use in power transformer components. Through oil compatibility, dielectric strength, and kerosene compatibility evaluations, the study gauges their suitability for this application. The results reveal that PPSU, PEEK, and ULTEM 1010 exhibit promising characteristics, specifically in regard to dielectric breakdown voltage and kerosene and insulating oil compatibility. In contrast, Biofila presented severe cracking when exposed to the mineral oil and PVDF and PEEK-GF20 fall short in terms of dielectric strength, rendering them unsuitable. Kerosene compatibility assessments show minimal material changes, confirming that all studied materials have good resistance to this drying agent, commonly used on power transformers. This research aims to provides essential insights into material selection for a new generation of power transformer parts.

The present work evaluates the surface roughness of lattice structures produced in AISI 316 stainless steel, with laser powder bed fusion (LPBF). To this end, five lattice types were evaluated, namely cubic (C), truncated octahedron (TO), truncated cubic (TC), rhombicuboctahedron (RCO) and rhombitruncated cuboctahedron (RTCO) to determine the average roughness Sa by profilometry. For comparison, the surface roughness of a bulk specimen was also measured. The average roughness was Sa=7.3 mm for the bulk specimen, for the C and TC arrangements it was around 11 mm, while for configurations RCO, RTCO and TO it was in the range 18-22 mm, meaning that surface roughness increases for more complex structures. Values of Sa around 10-25 mm are reported in the literature for parts fabricated by LPBF for medical implants. If complex lattice arrangements are required, a study of the printing parameters is relevant, to achieve scaffolds with improved biomechanical performance.