Full field measurements of anisotropic stress intensity factor ranges in fatigue

The effects of anisotropy during mixed mode fatigue crack growth were studied in single crystal 316L stainless steel. An anisotropic least-squares regression algorithm using displacements from digital image correlation was developed to find the effective stress intensity factors, KI and KII, and the T-stress. Crack tip plastic zones were determined using an anisotropic yield criterion. Strains in the plastic zone obtained from digital image correlation showed a dependence on the crystallography and load ratio. Crack tip slip irreversibility was measured and showed an increasing trend with increasing crack length; this information is critical for describing crack growth behavior.