Surface cracks have been recognized as major causes for fracture
failures of ductile pipes. This paper intends to derive a normalized
fully plastic J-integral solution to mixed-mode fracture caused by
inclined surface cracks in pressurized ductile pipes. A combined
J-integral and finite element method is developed to evaluate the
J-integral for inclined surface cracks. A set of predictive formulas for
normalized fully plastic J-integrals are developed. It is found in this
paper that the normalized fully plastic J-integral increases with the
decrease of crack inclination angle and aspect ratios, and the increase
of strain hardening exponent. It is also found that the critical
locations of crack propagation occur between the surface point and the
deepest point of cracks when the inclination angle is relatively small.
The paper concludes that the developed formulas can accurately predict
the normalized fully plastic J-integrals along the front of inclined
surface cracks. The results presented in the paper can enable
researchers and practitioners to accurately predict the mixed-mode
fracture failure of pressurized pipes subject to inclined surface
cracks.