Cohesive modeling of fatigue crack retardation in polymers: Crack closure effect

A numerical model of fatigue crack growth retardation in polymers induced by artificial crack closure is proposed. The approach relies on the combination of cohesive modeling and a contact algorithm incorporated in the wake of the advancing crack to account for the effect of the introduced wedge. Numerical results are compared with existing experimental observations, showing the ability of the cohesive model to capture the key features of wedge-induced crack retardation. A study is conducted to quantify the effects of relevant parameters such as applied load levels, wedge distance to the crack tip and wedge stiffness. The model is also discussed in the context of self-healing polymers [White SR, Sottos NR, Moore J, Geubelle PH, Kessler M, Brown E, et al. Autonomic healing of polymer composites. Nature 2001;409:794–7], where the wedging effect is associated with the polymerization of the healing agent.