Composite stepped-lap adhesive joint analysis by cohesive zone modelling

Abstract The use of adhesive bonds has increased significantly in recent years and is now a predominant bonding technique in the aeronautical and automotive industries. Cohesive Zone Models (CZM), used together with the Finite Element Method (FEM), are a viable tool to predict the strength (Pm) of adhesive joints. The CZM combines strength criteria for damage initiation and fracture mechanics concepts for crack propagation. The main objective of this study is to numerically and experimentally evaluate the mechanical performance of adhesively-bonded stepped-lap joints with carbon-fiber reinforced plastic (CFRP) substrates under tensile loading. The influence of different overlap lengths (LO) and a ductile adhesive was also investigated. Experimental data was gathered and compared with numerical CZM results obtained using Abaqus®. A study of peel (σy) and shear (τxy) stresses in the adhesive layer was performed. A significant geometry effect was found on the maximum load (Pm) of the stepped-lap joints, with benefit for large LO; however, delamination should be taken into account mostly for the longer LO. The CZM technique was revealed to be a suitable tool in determining the behavior of composite stepped-lap joints.