The prediction of real and extreme irregular crack front growth paths directly determines the accuracy of evaluating residual fatigue life of structures.A method for studying the distribution of stress intensity factor(SIF)along the extremely irregular crack fronts was developed by using a notched member

which was geometrically most similar to an engineering structure

as the cracked body.Firstly

the local curvature changes caused by convex

concave

and small curvature radii along the crack front were characterized by high-resolution spline curves.Then

based on the sub-model method combined with adaptive meshing technique

the growth trajectory of irregular crack front was iteratively simulated to obtain the irregular crack propagation law.Finally

by comparing the predicted crack geometry with the experimentally measured crack location

size

and other information

the reliability of crack propagation driving force simulated by Franc3D was verified through examples.The results show that the predicted crack front trajectory basically coincides with the actual

and the SIF values along any normalized growth path are basically equal.The predicted residual life is very close to the experimental life

with an error of only 2.4%.