The influence of T-stress on the characteristics of a fatigue crack

The influence of the T-stress values on the propagation of fatigue cracks is analyzed. The parameters of the plastic zone are studied at two levels of applied stress, i.e. loading and unloading. The CTOD parameter and rp (plastic zone size) in the crack grow direction are discussed as a driving parameter of a fatigue crack propagation rate. The three ways of determination of propagation rate of a fatigue cracks are compared. Recommendations for applications of these methods are discussed