Prediction of semi-elliptical defect form, case of a pipe subjected to internal pressure

The fatigue propagation of a semi-elliptical surface crack in a pipe subjected to internal pressure is always an open question in spite of a number of numerical works. The crack front development is generally predicted by empirical relationships or parameters c and m of the crack propagation law. This fatigue propagation in the case of a pipe subjected to internal pressure have been obtained using a special device allowed to produce an internal pressure up to 700 bars. The crack aspect ratio development is similar to that of a crack in a plate submitted to tension. (orig.)