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.
When there is a social consensus that industrial assets are in fact heritage elements of cultural interest, their conservation and reuse must be considered with approaches that offer greater guarantees and that prevent their exposure to aggressive actions. In order for this to materialise, many aspects must be included in the decision-making process, from the characteristics of an asset and its surroundings, to the valuable aspects that distinguish it and that must be protected. This study aims to develop tools that guide the decision-making process regarding the most appropriate activity for each specific case study. Multicriteria Decision Support Techniques are evaluated as adequate support to create a proposal that fulfils these objectives. Furthermore, the Analytic Hierarchy Process is adapted to develop methodologies for assessing both the heritage value and the most compatible uses according to the characteristics of the asset. Subsequently, they are connected and such considerations regarding the heritage value of the asset are incorporated into the final decision. The tools developed are then applied to a case study to test their performance, assess their usefulness, and identify possible applications and future developments.
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.
Any research in any field needs an initial background, and in the same way, any decision should be supported by previous knowledge and study of the problem and its context. In the case of the industrial heritage, both the study of the typology and the decision making about the actions of conservation and reutilization of its assets must be based on a deep knowledge of the set of elements that the typology includes. All of that refers to the corresponding territory being analyzed, since the intensity and productive tradition will be different between each territory, region, or country. In that context, this paper represents the continuation of the main research line of the authors, and exposes their efforts to develop a useful tool for the study, management, and cultural promotion of the assets related to industrial heritage in Spain through the development of a multi-criteria catalogue of assets. Thus, based on the initial catalogue developed by some of the authors, this paper significantly increases the number of assets considered. In addition, it includes new classification criteria, reviews the observed trends, and establishes the future lines of work and suitable strategies for these kinds of initiatives.
Additive manufacturing technologies offer important new manufacturing possibilities, but its potential is so big that only with the support of other technologies can it really be exploited. In that sense, parametric design and design optimization tools appear as two appropriate complements for additive manufacturing. Synergies existing between these three technologies allow for integrated approaches to the design of customized and optimized products. While additive manufacturing makes it possible to materialize overly complex geometries, parametric design allows designs to be adapted to custom characteristics and optimization helps to choose the best solution according to the objectives. This work represents an application development of a previous work published in Polymers which exposed the general structure, operation and opportunities of a methodology that integrates these three technologies by using visual programming with Grasshopper. In this work, the different stages of the methodology and the way in which each one modifies the final design are exposed in detail, applying it to a case study: the design of a shoe heel for FDM—an interesting example both from the perspectives of ergonomic and mass customization. Programming, operation and results are exposed in detail showing the complexity, usefulness and potential of the methodology, with the aim of helping other researchers to develop proposals in this line.
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.
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.
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