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A ‘boundary layer’ finite element for thin multi-strake conical shells

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Title: A ‘boundary layer’ finite element for thin multi-strake conical shells
Authors: Boyez, A
Sadowski, AJ
Izzuddin, BA
Item Type: Journal Article
Abstract: Multi-strake cylindrical and conical shells of revolution are complex but commonplace industrial structures which are composed of multipl e segments of varying wall thickness. They find application as tanks, silos, circular hollow sections, aerospace structures and wind turbine support towers, amongst others. The modelling of such structures with classical finite elements interpolated using low order polynomial shape functions presents a particular challenge, because many elements must be sacrificed solely in order to accurately represent the regions of local compatibility bending, so-called ‘boundary layers’, near shell boundaries, changes of wall thickness and at other discontinuities. Partitioning schemes must be applied to localise mesh refinement within the boundary layers and avoid excessive model runtimes, a particular concern in incremental nonlinear analyses of large models where matrix systems are handled repeatedly. In a previous paper, the authors introduced a novel axisymmetric cylindrical shell finite element that was enriched with transcendental shape functions to capture the bending boundary layer exactly, permitting significant economies in the el ement and degrees of freedom count, mesh design and model generation effort. One element is sufficient per wall strake. This paper extends this work to conical geometries, where axisymmetric elements enriched with Bessel functions accurately capture the bending boundary layer for both ‘shallow’ and ‘steep’ conical strakes, which are characterised by interacting and independent boundary layers, respectively. The bending shape functions are integrated numerica lly, with several integration schemes investigated for accuracy and efficiency. The potential of the element is illustrated through a stress analysis of a real 22-strake metal wind turbine support tower under self-weight. The work is part of a wider project to design a general thre e-dimensional ‘boundary layer’ element.
Issue Date: 1-Sep-2018
Date of Acceptance: 18-May-2018
URI: http://hdl.handle.net/10044/1/60233
DOI: https://doi.org/10.1016/j.tws.2018.05.019
ISSN: 0263-8231
Publisher: Elsevier
Start Page: 535
End Page: 549
Journal / Book Title: Thin-Walled Structures
Volume: 130
Copyright Statement: © 2018 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/.
Keywords: Science & Technology
Technology
Engineering, Civil
Engineering
Conical shell
Thin axisymmetric shell
Bending boundary layer
Bessel functions
Finite element method
EXACT STIFFNESS MATRIX
WIND TURBINES
FATIGUE LOADS
GENERATION
THICKNESS
DESIGN
0901 Aerospace Engineering
0905 Civil Engineering
0913 Mechanical Engineering
Civil Engineering
Publication Status: Published
Online Publication Date: 2018-07-04
Appears in Collections:Civil and Environmental Engineering
Faculty of Engineering