Numerical evaluation of tensile-loaded tubular scarf adhesive joints

Abstract

Tubular adhesive joints are widely employed when joining tubes and rods. The loads to which these joints are subjected may be axial or torsional. When loaded in the axial direction, cylindrical joints present stress concentrations in the adhesive layer, as is the case of lap joints. To improve the joint strength in the axial direction, the cross-section of the tubes can be chamfered to produce a scarf tubular joint. The geometrical variations produced by machining the chamfers increase the overall bonding area, leading to higher joint strength. This study aims to compare the tensile performance of tubular scarf joints (TSJ) with aluminium (AW6082-T651) adherends, considering the variation of the scarf angle (α) from 45° to 3.43°; the joints were bonded with a moderately ductile adhesive, the Araldite® 2015. Firstly, through the comparison of experimental tests and numerical analysis of tubular lap joints (TLJ), the cohesive zone model (CZM) technique and respective cohesive parameters were validated. A CZM analysis was then performed on the TSJ to analyse peel (σy) and shear stresses (τxy) in the adhesive layer. Damage and joint strength analyses were also carried out, as well as the study of the dissipated energy for the different joint configurations. The CZM technique was validated, and the numerical analysed showed a major α effect, with benefits for smaller α, and improved stress distributions over TLJ.