Experimental and analytical investigation on the shear performance of double-lap adhesive joints with multi-layered adherends

In the present study, shear tests were carried out on double-lap adhesive joints between glass and PVC adherends to investigate their mechanical behaviour and to verify the effectiveness of steel reinforcement – with different thicknesses – for the inner PVC adherend. In particular, two different commercially available structural epoxy adhesives as well as glass and PVC adherends were used in the bonded joints. The first part of the study illustrates the analytical model used to calculate the stress distribution in the adhesives and bonded joints. The second part analyses the mechanical properties of the materials used, which were tested experimentally. The third part illustrates the results obtained on double-lap joints in classical and reinforced configurations. The results show that it is possible to improve the mechanical behaviour of the joint in terms of strength and stiffness. It is shown both experimentally and analytically that the use of thicker steel reinforcements does not lead to further significant improvements. The best mechanical performance is achieved in each configuration by the first epoxy adhesive. As far as the failure modes are concerned, while in the unreinforced configurations one observes the failure of the loaded adherend (“Stock-Break” Failure), in the reinforced joints only “Glass Failure” mode are observed, which is due to the different transfer of stresses.