Use of a ductile fracture model for pipes with axial defects for analysis of results of full-scale experiments

We consider the use of a ductile fracture model for pipes with axial defects, loaded by internal pressure, for calculation of the limiting burst pressure P_LL. We describe procedures for hydraulic and pneumatic testing of full-size pipes performed at VNIIST (All-Union Scientific Research Institute for the Construction of Trunk Pipelines, Moscow), and also the scheme for application of a surface notch. We have done a comparative analysis of the value of P_LL calculated from the relationships determined on the basis of a ductile fracture model for cylindrical bodies with cracks and the value obtained using familiar empirical formulas. Based on the calculations, we plot graphs for the distribution of the deviation of the calculated burst pressure from the true burst pressure as a function of the relative crack length ². We demonstrate the considerable effectiveness of the ductile fracture model for pipes with defects, which allows us to take into account the real shape of the defect and additional mechanical actions (longitudinal forces, bending moments).Translated from Problemy Prochnosti, No. 6, pp. 5–15, November–December, 1996.