The influence of combination of surface roughness and nanostructure of adhesive on the strength of adhesively bonded joints

Today, adhesive bonded joints are widely used in the aerospace and automotive industries as they make it possible to create extremely strong and lightweight connections in engineering applications. The most important factors in these applications are the roughness of the surface of the bonded material and the interaction of the adhesive with the surface. In this thesis study, surface roughness and normal tensile strength of nanocomposite adhesive were investigated in butt joints subjected to tensile loading. AA2024-T3 aluminum alloy was used as the bonded material, DP460 structural adhesive was used as the adhesive, and Graphene and Carbon Nanotube-COOH were used as nanostructures. Sanding and sandblasting methods were used to add roughness to the bonded surfaces. A two-dimensional axisymmetric finite element model was developed to gain insight into joint damage. When the damage load obtained from the experiments is examined, the maximum force values increase as the surface roughness increases. However, when the surface roughness reached high values, this increase in connection strength decreased. The amount of surface roughness reduced the normal stress value of the joint due to the decrease in the adhesion of the adhesive to the bonded surface. When 1% by weight Graphene nanostructure was added to the adhesive, the maximum normal tension of the connections increased from 9% to 21%. When the same amount of Carbon Nanotube-COOH was added, it increased from 27% to 62%. Different normal stress values were obtained in the connections at the same roughness values obtained by sanding and sandblasting methods.