This paper presents a comparative study of the tensile mechanical behaviour of pieces produced using the Fused Deposition Modelling (FDM) additive manufacturing technique with respect to the two types of thermoplastic material most widely used in this technique: polylactide (PLA) and acrylonitrile butadiene styrene (ABS). The aim of this study is to compare the effect of layer height, infill density, and layer orientation on the mechanical performance of PLA and ABS test specimens. The variables under study here are tensile yield stress, tensile strength, nominal strain at break, and modulus of elasticity. The results obtained with ABS show a lower variability than those obtained with PLA. In general, the infill percentage is the manufacturing parameter of greatest influence on the results, although the effect is more noticeable in PLA than in ABS. The test specimens manufactured using PLA perform more rigidly and they are found to have greater tensile strength than ABS. The bond between layers in PLA turns out to be extremely strong and is, therefore, highly suitable for use in additive technologies. The methodology proposed is a reference of interest in studies involving the determination of mechanical properties of polymer materials manufactured using these technologies.

The lack of specific standards for characterization of materials manufactured by Fused Deposition Modelling (FDM) makes the assessment of the applicability of the test methods available and the analysis of their limitations necessary; depending on the definition of the most appropriate specimens on the kind of part we want to produce or the purpose of the data we want to obtain from the tests. In this work, the Spanish standard UNE 116005:2012 and international standard ASTM D638–14:2014 have been used to characterize mechanically FDM samples with solid infill considering two build orientations. Tests performed according to the specific standard for additive manufacturing UNE 116005:2012 present a much better repeatability than the ones according to the general test standard ASTM D638–14, which makes the standard UNE more appropriate for comparison of different materials. Orientation on-edge provides higher strength to the parts obtained by FDM, which is coherent with the arrangement of the filaments in each layer for each orientation. Comparison with non-solid specimens shows that the increase of strength due to the infill is not in the same proportion to the percentage of infill. The values of strain to break for the samples with solid infill presents a much higher deformation before fracture.

The use of current computer tools in both manufacturing and design stages breaks with the traditional conception of productive process, including successive stages of projection, representation, and manufacturing. Designs can be programmed as problems to be solved by using computational tools based on complex algorithms to optimize and produce more effective solutions. Additive manufacturing technologies enhance these possibilities by providing great geometric freedom to the materialization phase. This work presents a design methodology for the optimization of parts produced by additive manufacturing and explores the synergies between additive manufacturing, parametric design, and optimization processes to guide their integration into the proposed methodology. By using Grasshopper, a visual programming application, a continuous data flow for parts optimization is defined. Parametric design tools support the structural optimization of the general geometry, the infill, and the shell structure to obtain lightweight designs. Thus, the final shapes are obtained as a result of the optimization process which starts from basic geometries, not from an initial design. The infill does not correspond to pre-established patterns, and its elements are sized in a non-uniform manner throughout the piece to respond to different local loads. Mass customization and Fused Deposition Modeling (FDM) systems represent contexts of special potential for this methodology.

The present study offers a systematic review of the current state of research on lattice structures manufactured by additive technologies for biomedical applications, with the aim of identifying common patterns, such as the use of triply periodic minimal surfaces (TPMS) for bone scaffolds, as well as technological gaps and future research opportunities. Employing the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology, the review process ensures methodological rigor and replicability across the identification, screening, eligibility, and inclusion phases. Additionally, PRISMA was tailored by prioritizing technical databases and engineering-specific inclusion criteria, thereby aligning the methodology with the scope of this field. In recent years, a substantial surge in interdisciplinary research has underscored the promise of architected porous structures in enhancing mechanical compatibility, fostering osseointegration, and facilitating personalized medicine. A growing body of literature has emerged that explores the optimization of geometric features to replicate the behavior of biological tissues, particularly bone. Additive manufacturing (AM) has played a pivotal role in enabling the fabrication of complex geometries that are otherwise unachievable by conventional methods. The applications of lattice structures range from permanent load-bearing implants, commonly manufactured through selective laser melting (SLM), to temporary scaffolds for tissue regeneration, often produced with extrusion-based processes such as fused filament fabrication (FFF) or direct ink writing (DIW). Notwithstanding these advances, challenges persist in areas such as long-term in vivo validation, standardization of mechanical and biological testing, such as ISO standards for fatigue testing, and integration into clinical workflows.

Most of industrial heritage assets need new activities to ensure their survival. In addition, the collection of assets is very broad, many of their locations have now become central and are targets for speculation, and the nature of these sites displays great specialization. Consequently, processes for reusing these assets are necessary to conserve them, but they risk destroying features whose value has been inadequately identified. This work faces this multicriteria problem by adapting the Analytic Hierarchy Process (AHP) to create two independent criteria structures, one for heritage valuation and another for analyzing the spatial compatibility with new uses, and then connecting them considering the relations between criteria of both structures and the relevance of the heritage aspects involved. All this to select those activities that cause minimal harm to the heritage value to be conserved. This work analyses three case studies to evaluate the performance of a tool based on an adaptation of AHP. The results are exposed and some application guidelines are provided, since doubts in the way to applying and interpreting the criteria are in practice a common problem of this type of approaches and that is rarely addressed. Thus, this work shows the potential of the proposed tool as a resource for sustainable urban development strategies.

Additive manufacturing processes and products are very present in the current productive landscape, and in fact these technologies have been one of the most intensively studied and improved during the last years; however, there is still no defined and homogeneous regulatory context for this field. In this work, a thorough review of the main general and specific regulatory developments in design, materials and processes standards for additive manufacturing has been carried out, with special attention to the standards for mechanical characterization of polymer-based products. In many cases standards developed for other productive contexts are identified as recommended references, and some contradictory trends can be identified when different documents and previous experiences are consulted. Thus, as it is logical considering that all these technologies are involved in an intensive and continuous evolution process, there is a certain lack of clarity regarding the standards to be considered. This work aims to contribute to clarify the current standardization context in additive manufacturing and provide some guidelines for the identification of appropriate standards. The paper also emphasizes that the key for next regulatory developments in mechanical testing is to develop standards that consider particular AM processes along with materials. Moreover, a great gap between available standard about additive technologies based on metallic materials and polymer materials during the last years has been detected. Finally, the provided overview is considered of interest as support for research and practice in additive manufacturing, and both in intensive productive scenarios and for particular users and makers.