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Science and Technology of Nuclear Installations
Volume 2008 (2008), Article ID 685805, 8 pages
Research Article

Buckling of Imperfect Thin Cylindrical Shell under Lateral Pressure

Department of Mechanical, Nuclear and Production Engineering, University of Pisa, Via Diotisalvi 2, 56126 Pisa, Italy

Received 21 June 2007; Accepted 7 February 2008

Academic Editor: Siegfried Langenbuch

Copyright © 2008 R. Lo Frano and G. Forasassi. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The strength of thin shells, under external pressure, is highly dependent by the nature of imperfection. This paper investigates buckling behaviour of imperfect thin cylindrical shells with analytical, numerical, and experimental methods in conditions for which, at present, a complete theoretical analysis was not found in literature. In general, collapse is initiated by yielding, but interaction with geometrical instabilities is meaningful, in that imperfections reduce the load bearing capacity by an amount of engineering significance also when thickness is considerable. The aim of this study was to conduct experiments that are representative of buckling, in the context of NPP applications as, for instance, the IRIS (international reactor innovative and secure) and LWR steam generator (SG) tubes. At Pisa University, a research activity is being carried out on the buckling of thin walled metal specimen, with a test equipment (and the necessary data acquisition facility) as well as numerical models were set up by means FEM code. The experiments were conducted on A-316 test specimens, tubes with and without longitudinal welding. The numerical and experimental results comparison highlighted the influence of different types of imperfections on the buckling loads with a good agreement between the finite-element predictions and the experimental data.