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Projeto de investigação
Centre for Mechanical Engineering
Financiador
Autores
Publicações
Effect of bead characteristics on the fatigue life of shot peened Al 7475-T7351 specimens
Publication . Ferreira, N.; Jesus, J. S.; Ferreira, J. A. M.; Capela, C.; Costa, J. M.; Batista, A. C.
The present work aims to analyse the effect of shot peening processing parameters, material and size of beads on the fatigue behaviour of aluminium alloy AA7475-T7351. A systematic study was carried out on the roughness, surface hardening, residual stress profiles and fatigue life. Fatigue tests were carried out under both three points bending (3 PB) and tensile loadings. For 3 PB tests it was concluded that shot peening does not introduce significant improvement on fatigue life and that the use of low size glass beads is potentially beneficial, with roughness being as or more important than residual stresses. All tensile treated specimens presented an improvement of fatigue life in comparison to the untreated specimens, particularly when the crack initiated internally. Internal crack propagation generates a conical fracture surface until transition to mode I propagation.
Weldability of aluminium-copper in explosive welding
Publication . Carvalho, G. H. S. F. L.; Galvão, I.; Mendes, R.; Loureiro, A.; Leal, Rui
A large number of aluminium-copper explosive welds were produced under different welding conditions to perform a broad analysis of the weldability of this combination. The influence of the explosive mixture and the relative positioning of the plates on the welding results were analysed. When the aluminium alloy is positioned as the flyer plate, continuous interfacial melting occurred under the low values of energy lost by the collision, and collision point velocity. This proved that the weldability of the aluminium-copper combination is higher when the copper is positioned as the flyer. A mismatch between the experimental results and the existing theories that define the requirements for achieving consistent welds was noticed. Especially for welds produced using the aluminium alloy as the flyer, the experiments proved to be more restrictive than the theories. These theories, despite being widely applied in dissimilar welding literature, present several limitations concerning aluminium-copper welding. New approaches considering the formation of intermetallic phases at the interface, the properties of both welded metals, and/or the difference in their properties should be developed
Response of fabric insert injection overmolding PP based composites subjected to single and muti-impact
Publication . Ferreira, José; Febra, Tiago; Costa, José; Capela, Carlos
This paper presents the results of a current study on the development and impact response of composite plates manufactured by injection overmolding on the two sides of a single reinforcement fibre mat. The injection polymer is a talc-filled polypropylene, nowadays used for structural purposes. Three configurations with different insert fibre mats were used: Kevlar, biaxial and multiaxial glass fibre mats. The parameters studied were the fibre mat type and the impact energy. For single impact tests, it was concluded that the highest impact energy required to achieve impactor perforation is obtained with Kevlar insert, while the highest percentage of energy recovered is achieved with biaxial glass fibre netting. Kevlar insert also allows for the maximum impact stiffness. For the multi-impact tests, the recovered energy and the dynamic stiffness show the same tendencies of the single impact tests. On low energy impacts, the effect of the insert fibre and of the previous impact are quite reduced, while for impact energies above 6J, previous impacts reduce significantly the recovered energy and the impact energy for which the perforation was achieved.
Effectiveness of Wearable Devices for Posture Correction: A Systematic Review of Evidence from Randomized and Quasi-Experimental Studies
Publication . Caixeiro, Diogo; Cordeiro, Tomás; Constantino, Leandro; Carreira, João; Mendes, Rui; Silva, Cândida G.; Castro, Maria António
Introduction: The increasing development of wearable devices for postural monitoring (provide feedback on posture) or correction (mechanical or biofeedback to promote change) is partly driven by the rising prevalence of poor posture in the general population and its impact on pain perception and functional capacity. Objective: Examine the effects of wearable devices on posture correction or prevention and on related outcomes, including postural alignment, muscle activity, pain and functional performance. Methods: The review followed the PRISMA 2020 guidelines. Searches were performed in PubMed, Scopus, Web of Science, and PEDro for studies published between 2012 and 2025. Eligible studies included randomized controlled trials and quasi-experimental designs involving participants with postural deviations or at risk of developing them, who underwent interventions using wearable devices that provided vibratory, auditory, visual, or tactile biofeedback. Results: Eight studies reported immediate improvements in postural alignment, body awareness, and self-reported pain, particularly with devices providing vibratory or visual biofeedback. Functional task stability improved, and muscle activity during risky postures decreased. However, the strong heterogeneity across devices and protocols, small sample sizes, short intervention durations, and, in some cases, the lack of independent control groups limit the strength and generalizability of these findings. Conclusions: Wearable devices have potential as complementary tools in physiotherapy due to their autonomous and potentially effective nature. Nevertheless, current evidence remains insufficient to support definitive clinical recommendations.
Unidades organizacionais
Descrição
Palavras-chave
Mobility,Advanced Manufacturing Systems,Mechanical Engineering,Advanced Materials - Raw Materials, Engineering and technology ,Engineering and technology/Mechanical engineering
Contribuidores
Financiadores
Entidade financiadora
Fundação para a Ciência e a Tecnologia, I.P.
Programa de financiamento
Financiamento do Plano de Reestruturação de Unidades de I&D - 2013/2015 - OE
Número da atribuição
UID/EMS/00285/2013