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da Fonseca Matos Pragana, João Pedro

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  • Joining by forming of lightweight sandwich composite panels
    Publication . Contreiras, Tomás R. M.; Pragana, João; Bragança, Ivo; Silva, Carlos; Alves, Luís M.; Martins, Paulo
    This paper presents a new joining by forming process to assemble longitudinally two metal-polymer sandwich composite panels perpendicular to one another. The process combines sheet-bulk forming with mortise-and-tenon joints to produce mechanically interlocked joints with large and stiff flat-shaped heads. Experimentation and finite element modelling with representative unit cells give support to the presentation and special emphasis is placed on the application of the process to the fabrication of lightweight composite panels for structural applications. Failure of the joints takes place by cracking and not by disassembling after unbending the flat-shaped head of the joint back to its original shape. The required forces to produce the new type of joints are below 15 kN, allowing them to be an easy to implement alternative to existing solutions based on adhesives or fasteners.
  • Joining by forming of metal-polymer sandwich composite panels
    Publication . Pragana, João; Contreiras, Tomás R. M.; Bragança, Ivo; Silva, Carlos; Alves, Luís; Martins, Paulo
    This article presents new joining-by-forming processes to assemble longitudinally two metal-polymer sandwich composite panels perpendicular to one another. Process design draws from an earlier development of the authors for metal sheets to new concepts based on the combination of sheet-bulk forming with mortise-and-tenon joints. Selected examples obtained from experimentation and finite element modelling give support to the presentation. A new three-stage joining by the forming process is capable of producing mechanically locked joints with larger and stiffer flat-shaped heads than those fabricated by alternative single- or two-stage solutions. Failure in the new three-stage joining by the forming process is found to take place by cracking instead of disassembling after unbending the flat-shaped head of the joint back to its original shape. The required forming forces to produce the new metal-polymer joints are below 15 kN, allowing them to be an effective, easy-to-implement alternative to existing solutions based on adhesive bonding, welding and mechanical fastening.