Influence of adhesive thickness on local interface fracture and overall strength of metallic adhesive bonding structures

Adhesive bonding structures are widely used in a variety of engineering fields. Their overall strength is dependent on the cohesive properties involving local interface fracture. In the present research, the influence of the adhesive thickness on the cohesive properties and the overall strength of metallic adhesive bonding structures are investigated, with the cohesive zone model employed to equivalently simulate the adhesive layers with various thicknesses. A theoretical approach has been developed to determine the cohesive parameters for the present model when the adhesive thickness is varied. And then some numerical examples are given to explore the adhesive thickness-dependence overall strength of the adhesive joints, followed by some comparisons with the existing experimental results. Furthermore, the variations of both the cohesive parameters and the overall strength with the various thicknesses are influenced by some intrinsic characteristics of adhesives, which are investigated finally. The results show that both the cohesive parameters and the overall strength of metallic adhesive bonding structures are much dependent on the adhesive thickness, and the variations of overall strength resulting from the various thicknesses have discrepancy due to the toughness and strain hardening capacity of adhesives.