Parametric cohesive zone analysis of bi-adhesive single-step joints

Abstract

The industry has advanced in replacing traditional joining methods, such as screwing/riveting and welding, especially the aeronautical and automotive industries, which have adopted the adhesive bonding method. This method has the advantages of simplifying the process, improving performance in terms of fatigue load, and improving the union between dissimilar materials. In addition, the development of computational numerical methods, with greater precision, has contributed to the dimensioning of joints, as well as the prediction of the resistance of these joints, which has contributed to more reliable simulations of different adhesive bonding solutions and their industrial implementation. Different modifications to the conventional designs are addressed in the literature to achieve the best results, including geometrical and material modifications. In the present research, the strength of single-step single-adhesive joints and bi-adhesive joints (BAJ) manufactured with AW 6082-T651 aluminium adherends is experimentally and numerically studied for different overlap lengths (LO). Three commercial adhesives were studied, from brittle to ductile, along with different adhesive combinations in the BAJ technique. The experimental work was mainly used for numerical model validation. The numerical analysis took advantage of triangular cohesive zone models (CZM) and included the study of peel and shear stresses, strength, and energy to failure. It was possible to validate the CZM accuracy by comparison with the experimental data. The analysis carried out showed that the BAJ technique did not reveal significant increases in strength compared to single-adhesive joints. However, when damage tolerance and dissipated energy are analysed, a noticeable increase in performance is observed, especially in joints with larger LO.