Self-pierce Riveting and Riv-bonding of densified superwood to aluminum for structural applications

Densified superwood, a renewable material being developed for lightweight structural applications, requires effective methods for joining to metallic materials like aluminum. While adhesive bonding provides high joint strength, its limited elongation during lap shear tensile testing poses challenges for automotive applications. This paper presents an experimental study on self-pierce riveting (SPR) and riv-bonding (a combination of SPR and adhesive bonding) for joining superwood to aluminum. SPR successfully joins superwood to aluminum alloys, achieving reasonable strength (about 1-kN load) and significantly higher elongation (about 2-mm displacement) compared to adhesive-only bonds. Riv-bonding, which combines the advantages of both methods (about 5-kN load and about 4-mm displacement), offers an effective solution for superwood-to-aluminum joints for structural applications. The study reports the effects of rivet geometry, insertion speed, superwood coating, pre-drilling, and adhesive curing to identify optimal procedures for SPR and riv-bonding in these applications.