Fracture analysis of the long-deep semielliptical internal circumferential cracks grow from surface to fully through-wall crack in tubular members

This paper concerns the fracture analysis of the internal circumferential semielliptical surface crack penetrating the tube thickness subjected to axial tension by means of finite element method. The stress intensity factors for a wide range of long-deep semielliptical surface crack, semielliptical partly through-wall crack, and fully through-wall crack are presented. Since the stress intensity factors for deep surface crack with a/T ratio larger than 0.8 and partly through-wall crack are rarely presented in literature before, refined finite element models were prepared and analyzed for obtaining the stress intensity factors from the stage of semielliptical surface crack to partly through-wall crack. By applying neural network, a comprehensive set of equations for stress intensity factors have been produced. Based on these equations, all SIFs within the range of parameters can be obtained.