Tensile behavior of single strap-scarf joints using adhesive reinforced with carbon nanotubes: A combined experimental and numerical approach

This study investigates the tensile behavior of single strap-scarf adhesive bonded joints reinforced with carbon nanotube (CNT)-modified epoxy, using a combined experimental-numerical approach. The originality of this work lies in the systematic assessment of CNT reinforcement and geometric parameters-including scarf angle (30°,45°, 60°, 90°), strap length and thickness-on the strength and failure behavior of AA6061-T6/WEICON F2 adhesive joints. Adhesives containing 0, 0.5, 1.0, and 1.5 wt.% CNTs were prepared, with the 0.5 wt.% formulation exhibiting superior mechanical performance. Experimental tests were performed under static tensile loading, while finite element (FE) analyses employing a cohesive zone model (CZM) predicted stress distribution and failure initiation. Results demonstrated that the addition of 0.5 wt.% CNTs increased joint strength by 17.8%. Increasing patch length and thickness enhanced strength by 28.6% and 37.8%, respectively. Moreover, the single strap-scarf joint showed 33.7% higher load capacity than the single strap joint and 234% higher than the scarf joint. Failure was predominantly cohesive within the adhesive layer and correlated well with FE predictions.