Evaluation of strength and performance for a single lap bonded joint by insertion of structural elements in adhesive

The present study aims to validate bond strength of SLJs with dissimilar adherends such as CFRP and Aluminum. Aluminum adherend was considered for surface treatment using Resin pre-coating (RPC) and NaOH for SLJs, as well as mixing structural elements (ZnO tetrapods) within the adhesive. Young-Laplace measurement technique was used to determine the contact angle for specimens with different surface treatments. Nondestructive testing (NDT) methods like ultrasonic testing(UT) and X-ray radiography were used to determine the defects of the SLJs. The strength of the bond was assessed using flexural and tensile test equipment in UTM. Improved bonding performance was observed in terms of maximum load and shear strength of RPC surface treated specimens when compared to surface specimens without treatment. The structural elements mixed into adhesive showed improved bonding performance in terms of flexural strength. A numerical simulation model was developed for validating the results. The morphological studies of de-bonded joints to analyze the bonding mechanism in each group of specimens with maximum load bearing were done.