Centre for Mechanical Engineering

Publications

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.

2020-05Journal article

Open access

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

2019-05-12Journal article

Restricted access

Keywords

Mobility,Advanced Manufacturing Systems,Mechanical Engineering,Advanced Materials - Raw Materials, Engineering and technology ,Engineering and technology/Mechanical engineering

Funding agency

Fundação para a Ciência e a Tecnologia, I.P.

Funding programme

Financiamento do Plano de Reestruturação de Unidades de I&D - 2013/2015 - OE

Funding Award Number

UID/EMS/00285/2013