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Deformation and buckling of pipe elbow under bending in the plane of the elbow centerline

FROM:
S. A. Karamanos (1), E. Giakoumatos (1) and A. M. Gresnigt (2)
(1) Department of Mechanical and Industrial Engineering, University of Thessaly, Volos 38334, Greece
(2) Faculty of Civil Engineering and Geosciences, Delft University of Technology, 2600 GA Delft, The Netherlands

“Nonlinear Response and Failure of Steel Elbows Under In-Plane Bending and Pressure”, ASME J. Pressure Vessel Technol., Vol. 125, No. 4, November 2003, pp. 393-402, doi:10.1115/1.1613949

ABSTRACT: The paper investigates the response of elbows under in-plane bending and pressure, through nonlinear finite element tools, supported by experimental results from real-scale tests. The finite element analysis is mainly based on a nonlinear three-node "tube element," capable of describing elbow deformation in a rigorous manner, considering geometric and material nonlinearities. Furthermore, a nonlinear shell element from a general-purpose finite element program is employed in some special cases. Numerical results are compared with experimental data from steel elbow specimens. The comparison allows the investigation of important issues regarding deformation and ultimate capacity of elbows, with emphasis on relatively thin-walled elbows. The results demonstrate the effects of pressure and the influence of straight pipe segments. Finally, using the numerical tools, failure of elbows under bending moments is examined (cross-sectional flattening or local buckling), and reference to experimental observations is made.

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