A fatigue–damage–friction interface model for high-cycle fatigue analysis

The prediction of fatigue-driven crack initiation and growth is essential for evaluating the in-service performance of engineering components, as structural failure is commonly triggered by cyclic load conditions considerably lower than the thresholds associated with monotonic failure. Incorporating fatigue effects into cohesive zone models enables a more realistic representation of damage evolution, providing critical insights for durability assessment and life prediction. This paper introduces a procedure to apply a cohesive zone model for high-cycle fatigue crack growth. The proposed formulation accounts for damage and fatigue in mode I, mode II and mixed mode, friction and unilateral contact. The cohesive law is characterized by an exponential softening described by a relatively simple relation that allows for straightforward inversion. Unlike conventional approaches, the present formulation predicts fatigue-driven damage accumulation already in the elastic range, before the cohesive strength is attained. High-cycle fatigue analyses can be dealt by using the maximum and minimum loading envelopes instead of the full cycle-by-cycle history. The proposed model is integrated in time through a closed-form approximation, allowing to consider time steps far greater than the period of the applied cyclic load. The soundness of the approach is proved through various examples, with results validated against existing numerical benchmarks. This study provides a first step towards the modeling high-cycle fatigue-driven failure in complex interface systems.