Experimental and numerical investigation on the tensile performances of bonded/bolted hybrid CFRP‐AL joints

Abstract Reasonably designed hybrid joints can combine the advantages of both adhesively bonded and bolted joints, and have potential application value in improving the bearing capacity of the joint and ensuring structural safety. However, the failure behavior and damage mechanism of multi‐materials hybrid joints are not fully understood. In this paper, the mechanical performances of bonded, bolted, and hybrid CFRP‐aluminum alloy joints under tensile load were investigated using experiment and simulation methods. Based on the quasi‐static tensile test and fractography analysis, the mechanical behavior and damage mechanism of the three kinds of joints were studied, and the effects of hybrid effects were analyzed. The results demonstrated that there is no obvious co‐bearing effect between the adhesive layer and the bolt within the hybrid joint. Instead, a sequential load transfer behavior was observed. The hybrid joint showed more severe damage compared with the bolt joint, especially the CFRP delamination. Furthermore, a numerical model based on continuous damage mechanics (CDM) was established, the LaRC05 initial failure criterion and linear damage evolution were implemented to predict composite intra‐laminar failure, and the cohesive zone model (CZM) was used to simulate the inter‐laminar delamination and adhesive layer fracture. The model considers in situ effect, shear nonlinearity, and employs the selective parabola algorithm to improve computing efficiency. The comparison between experiment and simulation reveals that the model can accurately predict the mechanical performances of joints and capture the various failure modes. Highlights The performances of bonded, bolted, and hybrid CFRP‐aluminum alloy joints. The CDM model of CFRP includes LaRC05 criterion and stiffness degradation. Effect of damage constitutive models on the failure simulation of CFRP. Damage evolution and failure modes of three types of joints.