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Geometric imperfections and lower-bound methods used to calculate knock-down factors for composite cylindrical shells

Castro, Saullo and Zimmermann, Rolf and Arbelo, Mariano and Khakimova, Regina and Hilburger, Mark and Degenhardt, Richard (2014) Geometric imperfections and lower-bound methods used to calculate knock-down factors for composite cylindrical shells. Thin-Walled Structures, 74, pp. 118-132. Elsevier. doi: 10.1016/j.tws.2013.08.011. ISSN 0263-8231.

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Official URL: http://http://www.sciencedirect.com/science/article/pii/S026382311300205X


The important role of geometric imperfections on the decrease of the buckling load for thin-walled cylinders had been recognized already by the first authors investigating the theoretical approaches on this topic. However, there are currently no closed-form solutions to take imperfections into account already during the early design phases, forcing the analysts to use lower-bound methods to calculate the required knock-down factors (KDF). Lower-bound methods such as the empirical NASA SP-8007 guideline are commonly used in the aerospace and space industries, while the approaches based on the Reduced Stiffness Method (RSM) have been used mostly in the civil engineering field. Since 1970s a considerable number of experimental and numerical investigations have been conducted to develop new stochastic and deterministic methods for calculating less conservative KDFs. Among the deterministic approaches, the single perturbation load approach (SPLA), proposed by Hühne, will be further investigated for axially compressed fiber composite cylindrical shells and compared with four other methods commonly used to create geometric imperfections: linear buckling mode-shaped, geometric dimples, axisymmetric imperfections and measured geometric imperfections from test articles. The finite element method using static analysis with artificial damping is used to simulate the displacement controlled compression tests up to the post-buckled range of loading. The implementation of each method is explained in details and the different KDFs obtained are compared. The study is part of the European Union (EU) project DESICOS, whose aim is to combine stochastic and deterministic approaches to develop less conservative guidelines for the design of imperfection sensitive structures.

Item URL in elib:https://elib.dlr.de/90104/
Document Type:Article
Title:Geometric imperfections and lower-bound methods used to calculate knock-down factors for composite cylindrical shells
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Castro, SaulloPFH GöttingenUNSPECIFIED
Arbelo, MarianoPFH GöttingenUNSPECIFIED
Degenhardt, RichardDLRUNSPECIFIED
Journal or Publication Title:Thin-Walled Structures
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1016/j.tws.2013.08.011
Page Range:pp. 118-132
Keywords:Buckling; Composite; Axial compression; Geometric imperfections; Knock-down factor; Cylinders
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Transportation
DLR - Research area:Raumfahrt
DLR - Program:R RP - Space Transportation
DLR - Research theme (Project):R - Raumfahrzeugsysteme - HL-Primärstrukturen für Orbitale Systeme (old)
Location: Braunschweig
Institutes and Institutions:Institute of Composite Structures and Adaptive Systems > Structural Mechanics
Deposited By: Degenhardt, Richard
Deposited On:11 Aug 2014 08:14
Last Modified:20 Jun 2021 15:45

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