A critical assessment of computational fatigue crack driving force determination procedures utilising the strip-yield model framework

The strip-yield concept of elastic–plastic fracture mechanics, which was first proposed more than 50 years ago, currently serves as the foundation of many of the most advanced fatigue life evaluation procedures. Some studies of fracture and fatigue problems have reported a satisfactory agreement between experimental data and computational predictions, while others have demonstrated discrepancies and highlighted the limitations of the strip-yield concept. Some of these limitations and discrepancies are due to intrinsic simplifications, but others are related to its numerical implementation. This paper assesses computational crack driving force determination procedures based on recently developed analytical solutions for propagating cracks, which utilise the same modelling framework. It highlights several shortcomings of the current computational procedures associated with the meshing of the cyclic plasticity region and the use of constraint factors to represent thickness effects. Based on analytical solutions, several parameters derived from the model are evaluated as potential fatigue driving forces. The results can be used for validation purposes, aiming to reduce the controversy involved in the applications of strip-yield concept framework to fracture and fatigue.