FRANCISCO JOSE BREDA
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Resumo IPEN-doc 26834 Mechanical anisotropy of ABS specimens 3D printed by FDM2019 - ANDRADE, ARNALDO H.P. de; LOBO, RAQUEL de M.; BREDA, FRANCISCO J.; CASTAGNET, MARIANOAdditive manufacturing (AM) has been developed as a technique for fast fabrication of component parts through 3D printing, using a process of adding successive layers, one after another. The Fused Deposition Modeling (FDM) technique is a 3D printing process that generally uses a thermoplastic filament as the printing base material. The material is fed by a coil and the head of the extruder performing the process is heated. Printing can be done in several directions, depending on the purpose of the component part. In this work mechanical tests were done on ABS (Acrylonitrile-Butadiene-Styrene) tensile specimens built by FDM, in different orientations, to analyze its properties and to make a correlation between these properties and the influence of the printing direction in the final product. The tensile specimens in dog bone shaped were tested according to the ASTM D638 standards. The experiments were done at room temperature. The horizontal built specimens (H-specimens), fabricated in the z-direction, while the beads were layered along the x and y direction, parallel to the build table, showed the maximum resistance of 30 MPa. The specimens built with their gage length out of x-y plane (V-specimen and D-specimen, vertical and diagonal specimens respectively) presented lower ultimate strength, for instance 14 MPa for the Vspecimen. Additional investigation is on the way to understand the presence of defects (cavities and crazes) in the ABS microstructure since the literature points that the ability to manipulate it is the key to an improved performance of this type of structural material.Resumo IPEN-doc 26829 Fracture surface analysis of ABS samples printed by the FDM method2019 - LOBO, RAQUEL de M.; MORCELLI, APARECIDO E.; BREDA, FRANCISCO J.; CASTAGNET, MARIANO; ANDRADE, ARNALDO H.P. deFDM (Fused Deposition Modeling) is one of the most used technique in additive manufacturing (AM). It can be summarized as printing small components through a heated thermoplastic filament, which is deposited layer by layer through a 3D printer. The print head can be programmed to perform the job in different directions (X, Y and Z) even with predetermined slopes. In this work, flat tensile specimens were prepared in different directions using an ABS (Acrylonitrile-Butadiene-Styrene) filament with a processing temperature between 210-225 ° C. After tensile tests, the fracture surfaces were analyzed to get a better understanding of the deformation and fracture processes. The crosssection view of specimen´s morphology was examined with a scanning electron microscope at a very low accelerating voltage (1 kV). The specimens were coated with gold using a sputtering system. The specimens that showed the smaller ultimate strength (named V-specimen) presented numerous large cavities in its microstructure suggesting that these voids may have a major contribution to the mechanical performance of the material.The fracture surface also shows a possible pull-out between layers indicating a weak point in the microstructure of the built sample that’s requires further investigation.Resumo IPEN-doc 03729 Desenvolvimento e testes de detectores proporcionais de fluxo de gas para monitoracao de contaminacao alfa, beta e gama em pes e maos1990 - BANADOS PEREZ, H.E.; FIGUEIREDO, C.F.; VIEIRA, J.M.; BREDA, F.J.Artigo IPEN-doc 05187 Fadiga de alto ciclo de proteses ortopedicas1993 - PAES de ANDRADE, A.H.; BREDA, F.J.; PIMENTA JUNIOR, F.C.Artigo IPEN-doc 03483 Projeto, construcao e testes de camara de ionizacao de poco para deteccao de radiacao beta e gama1990 - BREDA, F.J.; BANADOS PEREZ, H.E.; VIEIRA, J.M.Dissertação IPEN-doc 08981 Estrategia de operacoes para pequenas producoes2003 - BREDA, FRANCISCO J.