New algorithm for optimised fitting of DIC data to crack tip plastic zone using the CJP model

The work presented in this paper provides guidance optimally determining the appropriate fitting region used digital image correlation (DIC) when a crack tip field model to DIC data. In work, technique is applied CJP and uses Levenberg-Marguardt (L-M) iterative method solve for position. This combined with an error analysis of main term Williams series expansion stresses extrapolation Saint-Venant’s principle determine optimum use fit multi-parameter solution model. A comparison then made between size shape plastic zone obtained using models. demonstrated that as increased, there was deterioration accuracy description expansion, while remains more accurate. addition, KF, stress-intensity factor drives growth has strong linear relationship area, which indicates KF direct driving force clear ?KCJP ?KI.