The effects of imperfections and nonlinearities on the failure mode and the B2 stress index of thin-walled straight pipes are investigated with finite element (FE) analyses. The analyses were performed for pipes made of an ideal elastic–plastic material and the austenitic steel X6CrNiNb18-10. The B2 index is calculated from the instability bending moments obtained by limit load analyses. The effects of initial imperfections as well as the D/t-ratio and the yield stress on the B2 stress index are studied. As a first result, it is noted that thin-walled straight pipes and imperfections fail due to local plastic buckling. Further analyses show that the type of imperfections, the ovality, the D/t-ratio, and the yield stress have significant influences on the B2 index. The obtained B2 indices for thin-walled straight pipes with D/t > 40 and possible technical imperfections are considerably higher than 1.0. The results have been compared with those of other investigations.
The Influence of Imperfections and Nonlinearities on the Failure and B2 Stress Index of Thin-Walled Pipes
Contributed by the Pressure Vessel and Piping Division of ASME for publication in the JOURNAL OF PRESSURE VESSEL TECHNOLOGY. Manuscript received April 28, 2014; final manuscript received April 8, 2015; published online May 20, 2015. Assoc. Editor: Spyros A. Karamanos.
Schau, H., Mkrtchyan, L., and Geier, M. (December 1, 2015). "The Influence of Imperfections and Nonlinearities on the Failure and B2 Stress Index of Thin-Walled Pipes." ASME. J. Pressure Vessel Technol. December 2015; 137(6): 061205. https://doi.org/10.1115/1.4030366
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