Experimental evaluation of the effect of overloads on fatigue crack growth by analysing crack tip displacement fields

In this work, the shielding effect on growing fatigue cracks under different overload levels is evaluated by estimating stress intensity factors from the analysis of crack tip displacement fields measured by digital image correlation (DIC). A novel model called CJP is implemented to characterise crack tip displacement fields. The retardation effect induced by overloads is quantified from the calculation of the crack opening load. Moreover, a compliance based method is employed to compare and validate those results obtained by DIC. Results show a good level of agreement, highlighting that CJP model is a powerful tool to evaluate fracture mechanics problems.