Design and testing of an innovative 3D-printed metal-composite junction

This paper describes an innovative 3D-printed beam-based lightweight structure that is used to increase the adhesion strength of metal-composite joints without damaging the composite fibers. It is conceived as the interface between the two parts to be joined: by filling the voids of this structure with resin, a mechanical interlocking effect can be generated to enhance the mechanical properties of the junction. A dedicated design workflow was defined to explore different types of 3D beam-based structures, starting from the analysis of the main failure modes of this type of junction. Tensile tests were performed on both polymeric and metal samples to validate the effectiveness of this interlocking strategy. Results demonstrated an increase in the adhesion strength relative to standard adhesive joints. A possible practical implementation is also discussed: a new type of insert is presented for application in metal-to-polymer composite joints. Finally, such a beam-based joining approach also represents an innovative application in the field of design for additive manufacturing.