IMPROVED STRESS-INTENSITY FACTORS FOR SEMI-ELLIPTICAL SURFACE CRACKS IN FINITE-THICKNESS PLATES.

This paper presents accurate stress-intensity factors for shallow and deep semi-elliptical surface cracks in plates using a three-dimensional finite-element analysis. To verify the accuracy of the solutions, convergence was studied by varying the degrees of freedom in the finite-element models. These models were composed of singular elements around the crack front and isoparametric elements elsewhere. Mode I elastic stress-intensity factors were calculated by using a nodal force method. To establish the validity of the present method, a circular crack and an elliptical crack were analyzed. The results obtained from the present method for these crack shapes were within 1 percent of the exact solutions obtained from the literature.