Ratcheting assessment of pressurized pipelines under cyclic axial loading: Experimental and numerical investigations

Abstract

The present study aimed to study ratcheting strains of pressurized stainless steel (UNS S32750) pipes with cyclic axial loading conditions. To this aim, some experiments were performed for the tubes involving cyclic axial loading under internal pressure. All specimens were analyzed with a finite element code. Ohno-Wang hardening model was employed in numerical analysis to calculate the ratcheting of the tubes. By using this hardening model, all predicted ratcheting results were consistent with those of the experimental ones. In this study, the effect of pre-compressed strain, internal pressure and stress amplitude were evaluated experimentally and the numerical results were compared with the results. Finally, the tubes collapsed at about the same strain level as it did under monotonic loading. The number of cycles to collapse and the ratcheting strain rate of the pressurized pipelines depend on the different parameters such as cyclic loading parameters, pre-strain and internal pressure. The results show that an increase of pre-strain, internal pressure and cyclic loading parameters leads to increase ratcheting strain rate of pipelines in both axial and circumferential directions.