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Projeto de investigação
Centre for Mechanical Technology and Automation
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Publicações
Asymmetrical rolling of aluminum alloys and steels: A review
Publication . 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.
Additive manufactured stoneware fired in microwave furnace
Publication . Santos, Tiago; Ramani, Melinda; Devesa, Susana; Batista, Catarina; Franco, Margarida; Duarte, Isabel; Costa, Luís; Ferreira, Nelson; Alves, Nuno; Pascoal-Faria, Paula
Additive manufacturing (AM) techniques have revolutionized the concept of building parts not only in laboratory contexts but also in industry environments and can be applied to distinct fields such as the health, automotive and aeronautics sectors [...]
Notch fatigue analysis and crack initiation life estimation of maraging steel fabricated by laser beam powder bed fusion under multiaxial loading
Publication . Branco, R.; Prates, P. A.; Costa, J. D.; Ferreira, J. A. Martins; Capela, C.; Berto, F.
This paper deals with the notch fatigue behaviour and crack initiation life estimation in maraging steel fabricated by laser beam powder bed fusion under multiaxial loading. Tests are conducted in tubular geometries with lateral holes considering different normal stress to shear stress ratios and multiaxial loading levels. The cyclic stress–strain response at the notch-controlled process zone is simulated numerically using two alternative approaches: a generalised isotropic plasticity model with mixed isotropic-kinematic hardening, and a linear-elastic model. Both approaches demonstrated to be suitable for predicting the crack initiation sites, the directions of crack growth, and the fatigue life. Fatigue life was calculated from a SWT-based model combined with the Theory of Critical Distances. Elastic-plastic predictions led to smaller errors but slightly shifted to the non-conservative side.
3D-printed multisampling holder for microcomputed tomography applied to life and materials science research
Publication . Vasconcelos, Isabel; Franco, Margarida; Pereira, Mário; Duarte, Isabel; Ginjeira, António; Alves, Nuno
The aim of this work was to design, fabricate, test and validate a 3D-printed multisampling holder for multi-analysis by microcomputed tomography. Different raw materials were scanned by microcomputed tomography. The raw material chosen was used to fabricate the holder by 3D printing. To validate the multisampling holder, five teeth were filled with a high density-material and scanned in two ways: a single and a multisampling scan mode. For each tooth, the root canal filling volume, porosity volume, closed pore volume, and open pore volume were calculated and compared when the same tooth was scanned in the two sampling scan mode. ABSplus P430™ allowed a high transmission value (84.3 %), and then it was the polymeric material selected to fabricate the holder. In a single sampling scan mode, the scan duration for scanning five teeth was 87.42 min, contrasting with 21.51 min for a multisampling scan mode, which scanned five teeth at the same time. The scan duration time and the cost using a multisampling holder represented a reduction of 75 % and the data volume generated represented a reduction of 60 %. Comparing the two scan modes, the results also showed that the difference of root canal filling volume, porosity volume, closed pore volume, and open pore volume was not statistically significant (p > .05). The multisampling holder was validated to do multi-analysis by microcomputed tomography without significant loss of quantitative accuracy data, allowing a reduction in scan duration time, imaging cost, and data storage.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDP/00481/2020