Application of bi-adhesive in double-strap joints subjected to bending moment

Generally, all failures in adhesively-bonded joints begin at the overlap ends because of the stress concentration occurring at the ends. The approach which reduces stress concentration at the overlap ends increases the load capacity and delays the failure. The lower the stiffness of the adhesive used, the lower the stress concentration, and the lower stress concentration gives rise to higher joint strength. In this work, the results of the application of two adhesives, one stiff and one flexible, with very different mechanical behaviors along the overlap length in double strap joints subjected to bending moment, were analyzed. A stiff adhesive was applied in the middle portion of overlap, while a flexible adhesive was applied towards the edges. The results show that the bi-adhesively-bonded joints carry more loads and have higher strength when compared with single-adhesively-bonded joints.