Browsing by Author "Sapage, Miguel S. T."
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- Joining of hybrid busbars for e-mobility: an economic and environmental studyPublication . Pragana, João P. M.; Sapage, Miguel S. T.; Sampaio, Rui F.V.; Bragança, Ivo; Ribeiro, Inês; Silva, Carlos M. A.; Martins, PauloThis paper presents a model to evaluate and analyze the costs of joining hybrid (copper-aluminum) busbars when different production processes are deployed. The process-based cost model (PBCM) is built upon the subdivision of the production cycle in three different stages related with the fabrication or purchase of auxiliary joining elements, preparation of the individual copper and aluminum conductors, and final joining of the hybrid busbars. The total cost per hybrid busbar is obtained by converting the major physical, human, and financial resources associated with the production cycle into itemized costs that make use of the expenses in materials, labor working hours, number and usage time of machines and tools, among other production costs. Application of the PBCM is illustrated with three different joining processes and enriched with a life cycle assessment (LCA) focused on the environmental performance of hybrid busbars throughout its fabrication, service use and end of life. The combined economic and environmental sustainability analysis of joining hybrid busbars allows concluding that despite conventional fastening being the cheaper process it has the highest environmental impact due to the use of bolts, nuts and washers made from galvanized medium carbon steel. Injection lap riveting arises to be the most well-balanced process in terms of production cost and environmental impact.
- Multi-planar injection lap rivetingPublication . Sapage, Miguel S. T.; Pragana, João P. M.; Sampaio, Rui F.V.; Bragança, Ivo; Silva, Carlos M. A.; Martins, PauloThis paper is focused on multi-planar hybrid busbars made from copper and aluminum for electric energy distribution systems. The objective is to provide an overview of its assembly by injection lap riveting in multidirectional tools and to compare the electrical performance of its joints against that of conventional (in-plane) busbars. The injected lap riveted joints require a dovetail ring hole and a countersunk hole to be first machined in the overlapped copper and aluminum sheets and then to inject the semi-tubular rivets by compression through the lined-up holes in order to fix the sheets in position. In this work, the injection of the semi-tubular rivets was carried out in a laboratory multidirectional tool set that converts the vertical press stroke into two-orthogonal horizontal movements by means of cam slide units consisting of compression punch holders and sliding wedge actuators attached to the upper bolster. Experimental results obtained for a multi-planar, three-conductor, rake-shaped elbow of a hybrid busbar system allow concluding that while the required compression force is proportional to the number of injected lap riveted joints, the electrical performance is non-proportional due to changes in the distribution of electric current density. Numerical simulation with finite elements gives support to the discussion and allows readers to recognize the pitfalls of designing busbar joints exclusively based on mechanical requirements.