RESEARCH ON THE GROWTH LAW OF EXTREME IRREGULAR CRACK FRONT IN NOTCHED COMPONENTS

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%.