Statistical analysis of adhesive rod-tube joints under tensile stress for structural applications

Adhesive bonding has been replacing traditional joining methods such as welding, bolting, and riveting in the design of mechanical structures in the automotive, aerospace and aeronautic industries. This joining method has several advantages over traditional methods such as ease of manufacture, lower costs, ease of joining different materials, higher fatigue resistance, and high corrosion resistance. Although tubular adhesive joints have varying applications, such as in truss structures and vehicles, machine axles, and piping, different joint configurations exist, such as rod-tube joints (RTJ), which are not conveniently addressed in the literature. This work compares the tensile performance of adhesively bonded RTJ between aluminium alloy components (AW6082-T651), considering the variation of the main geometric parameters: overlap length (L_O), tube thickness (t_S), rod diameter (d), adhesive fillet angle (f), and type of adhesive. The Taguchi’s method was employed in the elaboration of the applied design of experiments (DoE). To compare the RTJ behaviour, a numerical analysis was carried out through finite element analysis (FEA) and cohesive zone modelling (CZM). Peel (σ_y) and shear (τ_xy) stresses in the adhesive layer were initially obtained by applying purely elastic models. CZM modelling made possible to obtain the damage evolution in the adhesive layer, the maximum load (P_m) and dissipated energy (U) at P_m of the adhesive joints. As a result of applying the Taguchi method, the adhesive joint that showed the best overall performance used the adhesive Araldite^® AV138, L_O = 40 mm, d = 20, and t_S = 3 mm.