Prediction of failure behavior of adhesively bonded CFRP scarf joints using a cohesive zone model

In this article, the tensile behavior of adhesively bonded scarf joints (SAJs) of CFRP laminates with ductile adhesive is investigated by experiments and finite element (FE) simulations. Experimental tests considering joints with six different scarf angles are performed, and three-dimensional (3D) FE models are established in ABAQUS to study the failure mechanism. A user-defined cohesive zone model (UCZM) is proposed to predict the failure of ductile adhesive. The load-displacement response and failure modes of SAJs obtained by FE simulations are compared with the experimental results to validate the accuracy and applicability of UCZM. Moreover, the widely used triangular cohesive zone model (TCZM) is also employed to predict the failure. The comparison between experimental and numerical results exhibits that UCZM is able to predict the joint strength and failure displacement more precisely although TCZM also achieves certain accuracy. Furthermore, the influence of adhesive properties and composite stacking sequence on the tensile performance of joints is discussed using UCZM. Finally, the stress distribution within the adhesive layer and its variation along with different scarf angles are analyzed.