External longitudinal part-through flaw in an internally pressurised pipe

An external longitudinal surface flaw in a metallic round pipe subjected to internal pressure is considered. The defect is assumed to have an elliptical-arc shape, which is defined by the parameters  = a/t and  = a/b, where a and b are the semi-axes of the elliptical crack front and t is the pipe wall thickness. The parameter R/t, with R = internal radius of the pipe, is equal to 10 (thin-walled pipe). The stress-intensity factor distribution along the crack front is determined through a finite element analysis. Some results are compared to those deduced by other authors. Then a theoretical model based on the Paris-Erdogan law is applied to analyse the flaw propagation under cyclic internal pressure.