Mechanical characteristic and failure mechanism of joint with composite sucker rod

Composite sucker rods are widely used in oil fields because of light weight, high strength, and corrosion resistance. Bonded technology becomes the primary connection method of composites. However, the joints with composite sucker rods are prone to debone and fracture. The connected characteristics are less considered, so the failure mechanism of the joint is still unclear. Based on the cohesive zone model (CZM) and the Johnson-Cook constitutive model, a novel full-scale numerical model of the joint with composite sucker rod was established, and verified by pull-out experiments. The mechanical properties and slip characteristics of the joint were studied, and the damaged procession of the joint was explored. The results showed that: a) the numerical model was in good agreement with the experimental results, and the error is within 5%; b) the von Mises stress, shear stress, and interface stress distributed symmetrically along the circumferential path increased gradually from the fixed end to the loading end; c) the first-bonded interface near the loading end was damaged at first, followed by debonding of the second-bonded interface, leading to the complete shear fracture of the epoxy, and resulted in the debonding of the joint with composite sucker rod, which can provide a theoretical basis for the structural design and optimization of the joint.