ISEL - Engenharia Mecânica
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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.
- Thermal-electrical analysis of a novel interconnection for hybrid busbars in electric vehicle batteriesPublication . Costa, D. P. M. da; Kasaei, M. M.; Carbas, R. J. C.; Marques, E. A. S.; Sampaio, R. F. V.; Bragança, I. M. F.; Silva, L. F. M. da; Bragança, Ivo; ElsevierReliable and efficient busbar connections are critical for electric vehicle battery performance, yet conventional joining methods struggle with joining dissimilar materials such as copper and aluminum. This paper investigates a novel solution for joining hybrid copper-aluminum busbars using a technique called hole hemming, which eliminates the need for heating or additional elements. The focus is placed on the thermal-electrical performance of hole-hemming joints. Two configurations are studied: joints with and without branches. Numerical models analyse how sheet thickness affects temperature, electric current density, electric potential, and resistance, including models with cantered holes to study hole inclusion effects. Experimental tests are conducted on ma terial strips and unit cells to assess electrical resistance changes with temperature and the effect of Joule heating on joint configurations. Compression using a hydraulic press is applied to improve contact, leading to significant electrical resistance improvements (78 % reduction for branched joints and 36 % for branchless ones). Me chanical shear tests before and after compression show a peak shear load of 4.54 kN and 13.84 mm displacement for branched joints, with slightly lower values for branchless joints. Despite a minor decrease in mechanical performance after compression, the improved thermal-electrical performance of the joints outweighs this. The findings highlight the promising potential of hole-hemmed joints for enhancing hybrid busbar connections.