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- Pantograph-catenary offline hardware-in-the-loop hybrid testingPublication . Santos, J. P.; Antunes, P.; Pombo, J.; Rebelo, J. M.; Schirrer, A.; Jakubek, S.; Tur, M.; Gregori, S.; Pombo, João; ElsevierHybrid testing boosts the development and analysis of complex mechanical systems by combining physical testing with a computer-modelled environment. In railway dynamics, Hardware-in-the-Loop (HiL) simulation is a hybrid testing method sought after to study complex interactions, particularly between the pantograph and the catenary. Existing pantograph-catenary HiL approaches require real-time catenary models which restrict fidelity and spatial resolution. This paper proposes an iterative offline HiL method that removes this constraint while maintaining hybrid testing capability. The proposed methodology is established through a set of test experiments, considering different pantograph uplift forces and the stagger of the overhead contact wire. The feasibility and convergence of the proposed method is demonstrated for a set of test cases. Advantages and disadvantages of the online and offline approaches are discussed, together with further developments that may be considered to improve them.
- Macro-scale finite element simulation of wire-arc additive manufacturingPublication . Pragana, J. P. M.; Sampaio, R. F. V.; Bragança, I. M. F.; Silva, C. M. A.; Nielsen, C. V.; Martins, P. A. F.; Bragança, Ivo; SAGE Publications Ltd.This paper focuses on the development of a finite element computer software to perform macro-scale thermo-mechan ical simulations of wire-arc additive manufacturing (WAAM). The emphasis is placed on various aspects of computer implementation, such as modeling the heat source, incorporating an element birth approach to replicate material depos ition, and ensuring compatibility of solution time increments with the wire feed rate, travel speed of the heat source and melt pool volume. Thermal strains are also included due to their impact on residual stresses and distortions of the built parts after finishing material deposition. Experiments consisting of single bead, multi-layer deposition of AISI 316L stain less steel along linear paths are utilized to validate the predicted temperature distribution over time and evaluate the computed geometry and distortions of the deposited vertical walls after unclamping. Microstructure observations of samples extracted from the walls combined with finite element estimates of the temperature gradient help understand the influence of temperature history on the morphology and orientation of columnar grain growth.
- Formability assessment of additively manufactured materials via dieless Nakajima testingPublication . Sampaio, Rui F. V.; Rosado, Pedro M. S.; Pragana, João P. M.; Bragança, Ivo M. F.; Silva, Carlos M. A.; Rosa, Luís G.; Martins, Paulo A. F.; Bragança, Ivo; MDPIThis paper delves into the formability of material deposited by wire arc additive manufacturing. It presents a novel dieless Nakajima testing procedure that offers a practical solution for obtaining strain loading paths up to failure directly from the deposited material without the need for extracting sheet blanks. The procedure involved machining a region of the deposited material to the desired shape and thickness and using a press to drive and control the movement of a hemispherical punch. The test was designed using finite element modeling, and its effectiveness in obtaining the required strain loading paths directly from the deposited material was verified through experimentation with digital image correlation. Importantly, this novel test eliminates the need for the special-purpose tool setup required in conventional Nakajima sheet formability tests, thereby simplifying the overall testing process.
- Modelling of wire-arc additive manufacturing: a reviewPublication . Sampaio, Rui F. V.; Pragana , João P. M.; Bragança, I. M. F.; Silva, Carlos M. A.; Nielsen, C. V.; Martins, Paulo A. F.
- Automatic translator from Portuguese (voice and text) to Portuguese sign languagePublication . Domingues, Nuno Soares; Brito, Maeva de
- Using augmented reality to enhance education in science and engineeringPublication . Domingues, Nuno Soares
- Maintenance and life cycle analysis of biomedical devices in the pharmaceutical industryPublication . Patrício, João; Domingues, Nuno Soares
- Primary energy: a serious game to educate how to use energy in a sustainable wayPublication . Helena Aguiar; Jesus, Rui; Calado, J. M. F.; Henriques, Nuno; Domingues, Nuno
- Renewable energy and the politics of flow: sovereignty, ecology, and the ethics of water in the River BasinPublication . Domingues, Nuno Soares; Stanelyte, Daiva
- Electricity as a Commodity: Liberalisation Outcomes, Market Concentration and Switching DynamicsPublication . Domingues, Nuno Soares