Cohesive zone model prediction of debonding failure in CFRP-to-steel bonded interface with a ductile adhesive

A cohesive zone model (CZM) with triangular traction-separation law can predict the progressive fracture damage of the CFRP-to-steel bonded interface well with a brittle adhesive. Since a distinct plateau stage in the traction-separation relationship exists for a ductile adhesive, the triangular CZM cannot provide a valid prediction in this case. In the present article, a trapezoidal CZM using the finite element (FE) computational method was developed and coded in the user subroutine (UMAT) of ABAQUS to define the material property model of the cohesive layer. The debonding failure of the CFRP-to-steel bonded interface under single-mode and mixed-mode loadings were studied through FE analysis. The load-displacement relationship, the shear stress distribution, and the strain distribution obtained from FE simulation generally have good agreement with experimental results acquired from published papers. The effectiveness of the proposed FE model to simulate the progressive fracture damage of the CFRP-to-steel bonded interface with a ductile adhesive was validated.