Investigation of curved and scarf lap joints subjected to tensile loads using the cohesive zone model

In this study, curved lap joints were designed, particularly for the cases in which configuration or aerodynamic design was essential. Furthermore, the effect of the surface area on their strength was investigated. Hence, curved joint types were prepared on aluminum plates (A2024-T3) that are commonly used for aviation, and an angled joint type was created by increasing the radius of curvature. The created joint types were then joined by a two-component acrylic structural adhesive (DP410). The joint models were designed in three dimensions, and a finite element analysis was performed. Cohesive zone models (bilinear, exponential, and separation-distance) based on energy principles were used in the finite element analysis to estimate the strength of the adhesively bonded joint. The mechanical properties of the materials used in the joint models were experimentally determined to obtain the numerical solutions, which were validated by further experiments. The obtained results demonstrated that there was an increase in the surface area on which the adhesive was applied as the radius of curvature of the scarf lap joints decreased; however, this had an adverse effect on the failure load that was carried.