Brian Lau Verndal Bak

Interface elements for fatigue-driven delaminations in advanced composite materials

Abstract This chapter presents the formulation for an extension of quasi-static cohesive zone models to simulate fatigue-driven delaminations. The basis for the fatigue formulation is to link the evolution of the damage variable to the crack growth rate da/dN that can be measured in experiments. The model relates damage accumulation to the number of load cycles while taking into account the loading conditions (load ratio, energy release rate, and mode ratio). When used in a structural analysis, the model can simulate the dependence of the crack growth rate on these parameters. Moreover, the capability of the model to predict fatigue delamination over specimens without initial crack is presented. We also show that the model can be used to reproduce the curves Gmax–N used to predict the onset of fatigue delamination.