IDMEC Institute of Mechanical Engineering

Lisbon, Portugal

IDMEC Institute of Mechanical Engineering

Lisbon, Portugal

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Vidal C.,ICEMS Institute of Materials and Surfaces Science and Engineering | Vidal C.,Polytechnic Institute of Setúbal | Infante V.,ICEMS Institute of Materials and Surfaces Science and Engineering | Infante V.,University of Lisbon | And 2 more authors.
International Journal of Fatigue | Year: 2014

Friction stir channelling (FSC) is an innovative solid-state manufacturing technology able to produce continuous internal channels in a monolithic plate in a single step that can be used to produce conformal cooling/heating systems. During FSC a controlled amount of workpiece material flow-out from the processed zone producing the internal channel. The heat energy that softens the workpiece material is generated from dissipation during plastic deformation, internal viscous dissipation during the material flow and dissipation from frictional work between the tool and the workpiece. The purpose of this study is to investigate the fatigue behaviour of friction stir channelling specimens at elevated temperature. Fatigue tests were carried out at room temperature, 120 °C and 200 °C in a servo-hydraulic testing machine coupled with a furnace. The specimens were tested until fracture or up to 3 × 10 6 cycles. It was found that the fatigue resistance is dependent on the testing temperature. The results indicated that the fatigue life of an aluminium alloy friction stirred channel was reduced with increasing the testing temperature. Based on the fracture surfaces observations, the developing fatigue-crack always initiated at the advancing side, namely on the boundary between the nugget and the thermo-mechanically affected zone into the interior of the specimen. © 2013 Elsevier Ltd. All rights reserved.


Vidal C.,ICEMS Institute of Materials and Surfaces Science and Engineering | Vidal C.,Polytechnic Institute of Setúbal | Infante V.,ICEMS Institute of Materials and Surfaces Science and Engineering | Infante V.,University of Lisbon | And 2 more authors.
International Journal of Fatigue | Year: 2014

Friction Stir Channelling (FSC) is an innovative process within solid-state manufacturing technologies able to produce continuous internal or open channels in monolithic plates. The high level of adaptability of FSC makes it possible to apply to many different technical field domains and can bring significant advantages for already existent and new industrial applications. Because engineering components and structures are subject to accidental failures that occur due to unexpected or additional loadings, such as additional axial or torsion, this paper is focused on the effects of multiaxial loading paths on fatigue life of friction stir channelling monolithic plates of AA5083-H111 aluminium alloy. Uniaxial and biaxial fatigue tests were carried out with a stress ratio of R = -1. The FSC specimens used in this study were specially designed for the purpose. The fatigue behaviour was investigated by load controlled tests under uniaxial tension/compression loading and combined axial and torsional proportional loading. Metallographic analysis of the channel microstructure and fractograph analysis of the fracture surfaces were performed by optical microscope and SEM, respectively. For all tests carried out, the first crack always has initiated at the top of the advancing side namely in the boundary between the nugget and the thermo-mechanically affected zone. © 2013 Elsevier Ltd. All rights reserved.


Moreira S.F.,IDMEC Institute of Mechanical Engineering | Belinha J.,IDMEC Institute of Mechanical Engineering | Belinha J.,University of Porto | Dinis L.M.J.S.,IDMEC Institute of Mechanical Engineering | And 3 more authors.
MCB Molecular and Cellular Biomechanics | Year: 2014

In this work the maxillary central incisor is numerically analysed with an advance discretization technique - Natural Neighbour Radial Point Interpolation Method (NNRPIM). The NNRPIM permits to organically determine the nodal connectivity, which is essential to construct the interpolation functions. The NNRPIM procedure, based uniquely in the computational nodal mesh discretizing the problem domain, allows to obtain autonomously the required integration mesh, permitting to numerically integrate the differential equations ruling the studied physical phenomenon. A numerical analysis of a tooth structure using a meshless method is presented for the first time. A two-dimensional model of the maxillary central incisor, based on the clinical literature, is established and two distinct analyses are performed. First, a complete elasto-static analysis of the incisor/maxillary structure using the NNRPIM is evaluated and then a non-linear iterative bone tissue remodelling analysis of the maxillary bone, surrounding the central incisive, is performed. The obtained NNRPIM solutions are compared with other numerical methods solutions available in the literature and with clinical cases. The results show that the NNRPIM is a suitable numerical method to analyse numerically dental biomechanics problems. Copyright © 2014 Tech Science Press.

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