A modified hybrid method to estimate fracture resistance curve for pipes with a circumferential surface crack

This study presents a modified hybrid method to estimate the fracture resistance curve for pipes with a circumferential surface crack. The hybrid method combines a single experimental specimen with an extending crack and several numerical models with a stationary crack of different sizes, to calculate the fracture resistance directly from the pipe specimen. The strain energy used in estimating the fracture resistance derives from the load and crack-mouth opening displacement curve. The proposed method leads to good agreement in the estimated fracture resistance curves with those based on the unloading-compliance eta-approach, for both fracture specimens and for circumferentially surface-cracked pipes.