Numerical simulation of the failure of composite T-joints with defects

This paper focuses on the influence of defects in the filler and filler stiffness on the tensile strength of composite T-joints for their optimal design. A numerical model is developed to simulate the debonding and delamination of the composite structure by utilizing a cohesive zone model (CZM). The random crack path in the filler is also involved, and different sizes and locations of defects of the filler are taken into consideration. The present model is validated by experimental results. The load capacity of the structure is found to decrease with increasing defect size, and it is very sensitive to defects at the top of the filler. The damage tolerance performance of the composite T-joint is improved when filler stiffness increases from 3 MPa to 50 MPa. Failure modes are quite different for different forms of defects, but the random crack initiation or the final failure mode is always at the adhesive near the defect.