Elastic flexural behaviour of an adhesively bonded single lap joint with functionally graded adherends

This study investigates three-dimensional elastic flexural behaviour of an adhesively bonded single lap joint with adherends composed of a functionally gradient layer between a pure ceramic (Al2O3) layer and a pure metal (Ni) layer. The in-plane normal stress and shear stresses were critical in the adherends and adhesive layer. The left free edge of the upper adherend–adhesive interface, the right free edge of the lower adherend–adhesive interface and the corresponding zones in the upper and lower adherends experience stress concentrations whereas the middle overlap region has a uniform low stress distribution. The normal stress varies linearly through the adherend thickness and then becomes peak in the ceramic layer and in the metal layer. In the adhesive layer, the normal stress is peak at the left free edge of the upper adherend–adhesive interface and at the right free edge of the lower adherend–adhesive interface and then decreases uniformly across the adhesive layer towards the other adherend–adhesive interface. The functionally gradient region composed of layers with the mechanical properties calculated based on the power law. Accordingly, increasing the layer number had a minor effect on the through-the-thickness profiles and magnitudes of the critical stresses in both the adherends and the adhesive layer. In addition, enriching the material composition of the functionally gradient region with the ceramic phase does not affect the through-the-thickness profiles of critical normal and shear stresses of both adherends and adhesive whereas their magnitudes in the ceramic-rich layer of both adherends and along the adherend–adhesive interfaces increase considerably. On the contrary, the layer number and compositional gradient component affect evidently the through-the-thickness profiles and magnitudes of the critical normal and shear stresses in the adherends and adhesive layer of the functionally graded adhesively bonded joints subjected to thermal loads.