Cohesive zone modeling of fatigue crack growth in brazed joints

Abstract

Fatigue crack growth in low carbon steel brazed joints with copper filler metal is modeled by an irreversible Cohesive Zone Model. Strain-controlled fatigue tests are performed on the brazed specimens, and the corresponding fatigue crack initiation and propagation lives are recorded. A cyclic damage evolution law is coupled to a bilinear Cohesive Zone Model to irreversibly account for the joint stiffness degradation over the number of cycles. The damage law parameters are calibrated based on Irwin's analytical solution and the experimental fatigue crack growth data. Using the characterized irreversible Cohesive Zone Model, the fatigue crack growth is simulated and the corresponding fatigue crack growth rates are obtained. The agreement between the numerical results and the experimental data shows the applicability of the Cohesive Zone Model to fatigue crack growth analysis and life estimation of brazed joints.