A rate-dependent cyclic cohesive zone model incorporating material viscoelasticity and fatigue damage accumulation effects

Numerical simulation and analysis of high-frequency fatigue crack growth rates (FCGRs) have long been a challenging task in vibration fatigue assessment. The frequency effect on FCGRs can be effectively modeled through strain rate hardening. Additionally, the cyclic cohesive zone model (CCZM) has demonstrated good accuracy in simulating quasi-static fatigue crack growth (FCG). In this study, a rate-dependent cyclic cohesive zone model (RCCZM) is proposed by integrating the strain rate hardening term from the Johnson-Cook (J-C) model and the dynamic fracture toughness model with the CCZM. A linear scaling method is employed to improve both the speed and accuracy of FCGR predictions. The model is validated by comparing the theoretical range of FCGRs for aluminum alloys, based on dislocation dynamics theory, with experimental data for titanium alloys, and the extent of influence of the strain rate correction parameter is thoroughly analyzed. The RCCZM model demonstrates high reliability and accuracy, confirming that the frequency effect on metal FCGRs is primarily due to the strain rate's impact on strength, with minimal effect from fracture toughness.