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Axially compressed elastic-plastic axisymmetric collapse of 2 different tubes (A230 and A300) from flow theory versus deformation theory

FROM:
Rabee Shamass (1), Giulio Alfano (1) and Federico Guarracino (2)
(1) School of Engineering and Design, Brunel University, UB8 3PH Uxbridge, UK
(2) University of Naples ‘Federico II’, Via Claudio 21, 80125 Napoli, Italy

“A numerical investigation into the plastic buckling paradox for circular cylindrical shells under axial compression”, Engineering Structures, Vol. 75, pp 429-447, 15 September 2014,
DOI: 10.1016/j.engstruct.2014.05.050

ABSTRACT: It is widely accepted that for many buckling problems of plates and shells in the plastic range the flow theory of plasticity leads to a significant overestimation of the buckling stress while the deformation theory provides much more accurate predictions and is therefore generally recommended for use in practical applications. The present work aims to contribute to further understanding of the seeming differences between these two theories with particular regards to circular cylindrical shells subjected to axial compression. A clearer understanding of the two theories is established using accurate numerical examples and comparisons with some widely cited accurate physical test results. It is found that, contrary to common perception, by using a geometrically nonlinear finite element formulation with carefully determined and validated constitutive laws very good agreement between numerical and test results can be obtained in the case of the physically more sound flow theory of plasticity. The reasons underlying the apparent buckling paradox found in the literature regarding the application of deformation and flow theories and the different conclusions reached in this work are investigated and discussed in detail.

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