Fatigue crack propagation under mixed mode I

The propagation behavior of a circumferential crack in a cylindrical steel bar was studied under various combinations of cyclic torsional and axial loadings. The threshold condition of the onset of fatigue crack propagation from a pre-crack was expressed in terms of the stress intensity ranges for mode I and III. The J integral was applied to fatigue crack propagation with excessive plasticity under cyclic loading of mixed mode of I and III.