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- Direct Digital Manufacturing in the Context of a Circular EconomyPublication . Fonseca, Diana A.; Simões, FábioAdditive manufacturing technologies have evolved from prototype to part production. Coupling this shift with organizational transformations evolved rapid prototyping industry into Direct Digital Manufacturing (DDM) industry. Any evolution in production systems is now, more than ever before, dependent on sustainability principles. The development of the DDM industry must be guided by these principles, taking the chance it offers to change the production paradigm. Circular Economy (CE) is a shift in the production and resource management model, and one of the ways to work towards sustainability. Coupling DDM with CE principles is thus contributing to change industrial production to a more sustainable one. This paper intends to relate DDM technologies with CE principles, to identify aspects where DDM is contributing to CE, as well as aspects that should be explored further for that purpose. It is observed that DDM can enable optimization of material and energy usage, modify logistics towards de-localized production and recycling and enable prolonged lifespan of products through better access to spare parts, for instance. It is also observed that DDM has good potential to shift materials usage towards natural materials, especially in a context of consumer or local community production, but not so much within the current industrial context. Education is shown to play a pivotal role, since incorporating circular economy principles in educational contexts should spark a shift in consumer perspectives, modifying demand and hence, industrial production.
- Effect of asymmetrical rolling and annealing the mechanical response of an 1050-o sheetPublication . Simões, Fábio; Sousa, Ricardo J. Alves de; Grácio, José J. A.; Barlat, Frédéric; Yoon, Jeong WhanThe asymmetrical rolling process has been studied as a way to promote intense shear deformations across the sheet thickness. These shear deformations may lead, given the proper conditions, to the development of shear texture components ({001}<110>, {111}<110> and {111}<112>) and also grain refinement. In this work, a 1050-O sheet is asymmetrically rolled and annealed. Conventional rolling is also performed, for comparison purposes. Shear texture components are obtained for the asymmetrically rolled specimens, and seem to be retained after annealing. Differences in mechanical response between asymmetrical and conventionally rolled specimens, as well as texture evolution after heat treatment processing are inferred based on experimental tensile and shear tests. Numerical simulations are used to help explain the differences found on experimental tests. It is proven that it is difficult to spread shear texture through the entire sheet thickness from a general asymmetric rolling process. Based on the fact, future research is discussed at closure.
- Large scale additive manufacturing of eco-compositesPublication . Horta, João; Simões, Fábio; Mateus, ArturThe evolution of additive manufacturing processes is enabling the production of parts with improved dimensional accuracy, mechanical, physical and chemical properties [1]. New materials also contribute to this trend, and in this scope, eco-composites, materials with environmental and ecological advantages, which include natural polymers, have been acquiring increased relevance [2]. The purpose of this study is to develop composite material parts manufactured from recycled thermoplastics and natural fibres, in this case, wood residues. Additive manufacturing (fused deposition modelling) will be accomplished using a robot combined with extrusion unit. The objective is to access the influence of the main manufacturing parameters, such as temperature, distance between layers or deposition speed, on the final part characteristics, especially dimensional accuracy. Reverse engineering and several material analysis techniques will be employed to achieve this goal.
- International Conference on Quality, Innovation and Sustainability – ICQIS2020 - Book of AbstractsPublication . Pereira, Mário Rito; Simões, Fábio; Carlos Sá, José; Ferreira, Irene; Martinho, PedroThis book gathers the abstracts submitted and presented at the 2nd International Conference on Quality, Innovation and Sustainability, organized by the Polytechnic of Leiria and the Polytechnic Institute of Viana do Castelo on November 19 and 20, 2020. Abstracts are organized by session, and include keynote presentations, ordinary presentations and the poster session.
- Asymmetrical rolling of aluminum alloys and steels: A reviewPublication . Vincze, Gabriela; Simões, Fábio J.P.; Butuc, Marilena C.Asymmetric rolling is an attractive metal forming process due to its simplicity, low cost and capability to produce unique characteristics in materials. The asymmetry promoted by the process leads to a formation of a large collection of texture components and a refined structure which is capable to improve the mechanical behavior of metallic materials. The aim of this work is to present a perspective of the process and to construct the bases for future development and application of this technique. Thus, several aspects are addressed such as process methods (i.e., dissimilarity of the rolls diameters, rolls angular speed or friction conditions), the process parameters (i.e., total thickness reduction, thickness reduction per pass, peripheral speed ratio, rolling routes) and their effect on material properties, including texture and microstructure evolution, and mechanical properties. This review is focused on the experimental description of asymmetric rolling applied to aluminum alloys and steels. Although the asymmetric rolling application was mostly at a laboratory scale, there is a good perspective for its implementation in the industry. The pros and cons based on the up to date literature and authors’ experience are presented and discussed.
- A Polycrystal Model to Evaluate Mechanical Properties of Asymmetrically Rolled AL SheetsPublication . Sousa, R. J. Alves de; Simões, F. J. P.; Grácio, J. J.; Yoon, J. W.The asymmetric rolling process (ASR) differs from conventional rolling (CR) through the use of different roll circumferential velocities. Using proper parameters, asymmetric rolling imposes intense shear deformations across the sheet thickness, leading not only to the occurrence of shear texture, but also to grain refinement [1]. Some shear texture components are known to improve plastic strain ratio values, and consequently formability. In Simões et al. [4], a AA1050-O sheet was asymmetrically rolled and annealed. Shear texture was obtained, as opposed to typical gamma-fiber texture obtained on sheets rolled through the conventional process. Shear tests were used to evaluate strength and formability. A polycrystal plasticity model, as formulated by Gambin [2] and implemented by Alves de Sousa [3], was employed to evaluate texture evolution and to give a sounding theoretical basis for the improved mechanical properties on sheets after the process. For FCC materials, this approach avoids the uniqueness issue related to the choice of the set of active slip systems by applying a regularized Schmid Law. Consequently, it generates yield surfaces with smooth corners where the normal vector is always uniquely defined. In the following sections, implementation guidelines are given. The accuracy of simulation results and the advantages of the asymmetric rolling process, when compared to conventional rolling, are the main topics of discussion.
- Water Assisted Injection Molding for Single and Multi-branched Tubular ComponentsPublication . Oliveira, D.; Mateus, A.; Carreira, P.; Simões, F.; Malça, C.To produce hollow polymeric parts with complex geometries the Fluid Assisted Injection (FAI) technology is currently used. In this technology water and gas can be employed with or without the aid of a projectile. The process consists in the injection of water at high pressures, after the closing of the mold and polymer injection, and up to the filling of the whole molding zone. The injection of water at high pressures will force the polymer from the core to be expelled to a reservoir. This material expulsion is possible, not only thanks to the high water pressures, but also because the polymer is still in a viscous state, thus facilitating the evacuation. Even though the FAI technology is by direct injection of water/gas or with aid of a projectile, there is a common limitation, which is the inability to produce hollowed parts with forking channels. However, even if creating these branches is possible, there is the impossibility of them being geometrically complex and/or extensive. In these cases, the branches are created with inserts inside the mold, meaning that they will always be limited by a molding insert, and not controlled by the water jet. For cases where it is desired to add complex and/or extensive ramifications, subsequent steps of production and assembling must be added, influencing the overall production time. This work aims, therefore, at studying a new approach for the production of hollow parts with extensive branched channels and complex geometries within a single injection cycle, and thus eliminating subsequent processes that are currently required. The first approach is the application of several water injectors, guided towards the respective branches where hollow sections are intended to be produced. This innovation will have an impact on the serial production of high complexity tubular type parts, reducing the production time with the elimination of subsequent processes. Furthermore, a saving of raw materials is achieved by eliminating the necessity of a creation of additional molds. In this work, a detailed experimental study of the water assisted injection process was done to serve as a knowledge base to the concept of the new process named Multi-Path.H2O.