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- Cyclic plastic behaviour of 7075 aluminium alloyPublication . Nogueira, F.; Cunha, J.; Mateus, A.; Malça, C.; Costa, J. D.; Branco, R.This paper aims at studying the cyclic plastic behaviour of the 7075-T651 aluminium alloy under fully-reversed strain-controlled conditions. Tests are conducted under strain-control mode, at room temperature, in a conventional servo-hydraulic machine, from smooth samples, using the single step method, with strain amplitudes (∆ε/2) in the range ±0.5 to ±2.75%. This material has exhibited a mixed behaviour, i.e. cyclic strain-hardens at higher strain amplitudes (∆ε/2/>1.1%) and cyclic strain-softens at lower strain amplitudes (∆ε/2<1.1%). A linear relationship between the degree of cyclic strain-hardening and the strain amplitude has been established for higher strain amplitudes. Fatigue-ductility and fatigue-strength properties agree with those found in the open literature for the same loading conditions.
- Optimalmould - part II: Global optimization of the injection moulding cycle timePublication . Ramos, Carina; Carreira, Pedro; Bartolo, Paulo; Alves, NunoThe time required to produce a plastic part is a key issue in injection moulding process as it strongly determine the cost per part. Several approaches have been proposed to address this problem. However they do not cover all aspects related to the complete cycle time of the injection moulding process, only focusing on steps such as filling time, cooling time and packing time. This paper presents a global optimisation strategy for the injection moulding cycle time, covering all time steps related to the injection moulding process, including a novel mathematical model to predict the ejection time. An industrial case study was considered to validate the proposed approach. The obtained results are very close to the experimental ones. © 2012 American Institute of Physics.
- Optimalmould-part I: Multi-objective optimization to moulds design for injection of polymersPublication . Ramos, Carina; Carreira, P.; Bártolo, Paulo; Alves, NunoThe problem of mould design optimisation for polymer injection is a key issue for both mouldmaking and polymer injection industries. Several computational tools have proposed to address this problem. However they do not cover all aspects related to both mould design and injection moulding process, usually requiring the geometrical configuration of the initial mould solution. This paper presents a novel multi-objective optimisation tool, integrating CAD and CAE tools to optimise mould design parameters and injection moulding process parameters. No initial geometric definition of the mould is required. An industrial case study was considered to validate the proposed approach and the performance of several optimisation algorithms evaluated.