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High stress concentration at the free edges of Adhesively Bonded Joints (ABJs) is responsible for their debonding failure. This paper is to investigate the debonding initiation and growth in ABJs by means of a semi-analytic stress-function variational method and Cohesive-Zone-Model (CZM) based Finite Element Method (FEM). In particular, effects of the geometries, material properties, and debonding toughness of the adhesive layers on the free-edge stresses and global load-carrying capacity, i.e., the characteristic full-range load-displacement diagram, of an adhesively single-sided strap joint (ASSSJ) were examined. In the modelling, debonding initiation at the free edges of the ABJs is controlled according to a linear cohesive law in terms of the critical interfacial peeling (Mode-I) and shearing (Mode-II) fracture toughness. Numerical results show that the critical tensile force to trigger the debonding initiation in the ASSSJ increases nearly linearly with increasing interfacial debonding toughness and decreases slightly with increasing adhesive layer thickness. The effective longitudinal stiffness of the ASSSJ is nearly independent of the modulus of the adhesive layer and decreases by increasing adhesive layer thickness. In addition, the full-range load-displacement diagram of the ASSSJ during the entire debonding process exhibits a flat, seemingly, “yield” region corresponding to the stable debonding process, which indicates the excellent, controllable mechanical durability of the ASSSJ. The present studies demonstrate the capabilities of stress-function variational method and CZM-based FEM for determining the load-carrying capacity of ABJs, which are applicable to explore the failure mechanisms, reliable design, active debonding suppression, and extension of the mechanical durability of ABJs for use in broad structures. 

adhesively bonded joints (ABJs), cohesive zone model, fracture mechanics, debonding, finite element method, stress-function variational method.