11 documents found, page 1 of 2
Enhancing the performance of double-flush riveted joints through hybridization ...
Alpendre, João M. B.; Rosado, Pedro M. S.; Sampaio, Rui F. V.; Pragana, João P. M.; Bragança, Ivo; Silva, Carlos M. A.; Martins, Paulo A. F.This paper explores the potential to enhance the mechanical performance of joints created through a new joining-by-forming technique called hybrid double-flush riveting. To achieve this, adhesive bonding is used to form hybrid lap joints with superior mechanical properties. The study focuses on high-strength steel sheets and starts by identifying the appropriate surface conditions necessary for producing strong...
Multi-planar injection lap riveting
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 countersu...
Exploring wire-arc additive manufactured rivets for joining hybrid electrical b...
Rosado, Pedro M. S.; Sampaio, Rui F. V.; Pragana, João P. M.; Bragança, Ivo; Silva, Carlos M. A.; Martins, Paulo A. F.This paper presents a joining by plastic deformation process for fabricating hybrid electrical busbars made from copper and aluminum sheets. The process comprises the innovative use of wire-arc additive manufacturing to deposit copper rivets at specific locations on the copper sheets, the machining of slots with the required geometry in the aluminum sheets, and the compression of the copper sheets to force the ...
Joining of hybrid busbars for e-mobility: an economic and environmental study
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 fina...
An upset geometry sequence for determining the formability limits in bulk forming
Silva, Carlos M. A.; Sampaio, Rui F. V.; Pragana, João P. M.; Bragança, Ivo; Martins, Paulo A. F.This paper presents an upset geometry sequence capable of providing strain loading paths from uniaxial compression to biaxial stretching. Combination of digital image correlation and experimental force vs. time evolutions allows determining the fracture strains and the instantaneous slope of the strain loading paths at the instant of cracking in principal strain space. Fractography using scanning electron micro...
A joining by plastic deformation process to fabricate butt joints in copper-alu...
Pragana, João P. M.; Sampaio, Rui F. V.; Bragança, Ivo; Silva, Carlos M. A.; Martins, Paulo A. F.This paper presents a feasibility study on the fabrication of butt joints in copper-aluminium (hybrid) busbars by means of an innovative joining by plastic deformation process. The joints are obtained by cutting complementary fixing pairs consisting of fingers and grooves in the busbars and by subsequently upsetting the fingers, in position, to create a permanent interlocking with the grooves of an edge bent bu...
An upset geometry sequence for determining the formability limits in bulk forming
Silva, Carlos M. A.; Sampaio, Rui F. V.; Pragana, João P. M.; Bragança, Ivo M. F.; Bragança, Ivo; Martins, Paulo A. F.This paper presents an upset geometry sequence capable of providing strain loading paths from uniaxial compression to biaxial stretching. Combination of digital image correlation and experimental force vs. time evolutions allows determining the fracture strains and the instantaneous slope of the strain loading paths at the instant of cracking in principal strain space. Fractography using scanning electron micro...
Groove stiffening of sheets by single point incremental forming
Cristino, Valentino A. M.; Pragana, João P. M.; Bragança, Ivo; Silva, Carlos M. A.; Martins, PauloThis paper investigates the applicability of single point incremental forming to fabricate stiffening grooves in thin metallic panels. The work combines experimentation, finite element and analytical modelling to determine the required forces and the maximum allowable groove depths that can be produced without tearing. The analytical modelling is based on a framework that was previously developed by the authors...
A self-clinching fastener for hidden lap joints
Sampaio, Rui F. V.; Pragana, João; Bragança, Ivo M. F; Silva, Carlos M. A.; Martins, P. A. F.This paper presents a new self-clinching fastener to connect two sheets (or plates), made from similar or dissimilar materials, placed over one another by means of a mechanical form-closed joint that is hidden inside the sheets. The development of the fastener, the definition of its main design variables and the identification of its workability limits are carried out by means of a combined experimental and num...
Resistance element welding of sandwich laminates with hidden inserts
Calado, Francisco N.; Pragana, João; Bragança, Ivo; Silva, Carlos M. A.; Martins, Paulo A. F.This paper presents a new resistance element welding process capable of producing invisible lap joints between steel-polymer-steel composite laminates. The process involves pre-drilling a flat-bottom hole in each laminate to remove the polymer core and one of the steel sheets, and positioning a cylindrical insert inside the two adjoining holes for subsequent resistance welding. Finite element modeling is utiliz...