Determination of Mechanical Properties of Double-Strap Adhesive Joints with an Embedded Patch

In this study, stress analysis of double-strap joints used to fasten parts, particularly in aircraft and automotive industries and in the repair of damaged parts, was done using the finite element method. In classical double-strap adhesive joints, patch parts are bonded to the outer surface and these parts resist air flow. To decrease this effect and for constructive and aesthetic requirements, patch parts were embedded into the adherends. The effects of embedded patch parts on failure loads and stress distributions were investigated experimentally and numerically. For this purpose, AA 2024-T3 aluminum adherends with four different thicknesses (4.8, 5.6, 6.4 and 7.2 mm) were bonded as double patches with 0.4, 0.8 and 1.2 mm spring steel patch thicknesses and 20, 40 and 60 mm overlap lengths. The stress analyses were done under plain strain assumption. To verify the finite element model, experiments were carried out. The results show that adherends and patch thicknesses as well as overlap length all have considerable influence on failure loads and stress distributions.