On ΔJ characterization of elastic-plastic crack-tip fields under fatigue loading conditions

In the present paper, the applicability of the delta J-integral is computationally investigated under the Masing postulate. It confirms that the path-dependency of delta J is more severe than the delta J-integral under incremental plasticity. delta J from loading is up to 20% larger than delta J from unloading, which is independent of loading amplitudes but due to non-proportional stress variations. The stress range field can be characterized by delta J & nbsp;and shows an analogous mathematical structure as the known HRR solution, but not for the strain field under fatigue loading. The & nbsp;delta J dominant zone is much smaller than the HRR zone and further decreases with applied loading.