Global buckling response of web-core steel sandwich plates influenced by general corrosion

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Romanoff, Jani, Prof., D.Sc. (Tech.), Aalto University, Department of Applied Mechanics, Finland
dc.contributor.advisor Remes, Heikki, Prof., D.Sc. (Tech.), Aalto University, Department of Applied Mechanics, Finland Jelovica, Jasmin 2014-09-29T09:00:19Z 2014-09-29T09:00:19Z 2014
dc.identifier.isbn 978-952-60-5861-0 (electronic)
dc.identifier.isbn 978-952-60-5860-3 (printed)
dc.identifier.issn 1799-4942 (electronic)
dc.identifier.issn 1799-4934 (printed)
dc.identifier.issn 1799-4934 (ISSN-L)
dc.description.abstract A web-core steel sandwich plate is a lightweight, orthotropic structure. The constituent thin plates (2-4 mm) are joined by laser-welding. This thesis investigates the buckling and post-buckling behaviour of slender web-core sandwich plates loaded in the direction of the web plates. The influence of corrosion on the plate buckling is studied via finite element method (FEM). The corrosion scenario used is based on experimental observations from specimens submerged into the sea for 1 and 2 years. The plate strength analyses are performed with two methods: FEM having shell element mesh of the three-dimensional topology and the equivalent single-layer theory (ESL). In the later, the sandwich plate is represented with constant, homogenised stiffness coefficients, which are related to physical properties of the structure. The first buckling mode of slender web-core sandwich plates is characterised with global deformation between the edge supports. The buckling strength depends on the bending and transverse shear stiffnesses. This thesis revealed that the buckling strength is very sensitive to the variation in transverse shear stiffness opposite to the web plate direction, DQy, especially in sandwich plates with high bending stiffness. Furthermore, the stiffness of the sandwich plate as a whole in the post-buckling is controlled by that of the in-plane stiffness. The web plates impose high, shear-induced, secondary bending stresses on the face plates and these were found to be important for accurate estimation of the onset of yielding. The deformation resulting from the secondary bending of the face plates makes the unloaded edge stiffer. Although membrane stress can be higher there, local buckling during global post-buckling occurs further away where the secondary deformations are smaller, primarily in the centre of the face plate (x=a/2, y=b/2). Furthermore, the corrosion tests revealed that the cross-section is primarily affected by general corrosion. Under this circumstance, the reduction of the thickness of the face and web plates reduces the stiffness coefficients and also the buckling strength linearly. The buckling strength reduces rapidly, especially because of the reduction in the transverse shear stiffness DQy. The reduction of buckling strength doubles if, in addition to the outer faces, corrosion also occurs inside the sandwich plate. Beam bending tests also showed rapid reduction of the ultimate strength but, in addition, that it can be maintained using different protection methods. The results thus indicate that the protection against corrosion should be carefully performed. The future work will involve improving the accuracy of the ESL theory in the presence of local buckling. en
dc.format.extent 46 + app. 49
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher Aalto University en
dc.publisher Aalto-yliopisto fi
dc.relation.ispartofseries Aalto University publication series DOCTORAL DISSERTATIONS en
dc.relation.ispartofseries 140/2014
dc.relation.haspart [Publication 1]: Jelovica, Jasmin; Romanoff, Jani; Ehlers, Sören; Varsta, Petri. Influence of weld stiffness on buckling strength of laser-welded web-core sandwich plates. Journal of Constructional Steel Research, volume 77, pages 12-18, 2012. doi:10.1016/j.jcsr.2012.05.001.
dc.relation.haspart [Publication 2]: Jelovica, Jasmin; Romanoff, Jani. Load-carrying behaviour of web-core sandwich plates in compression. Thin-Walled Structures, volume 73, pages 264-272, 2013. doi:10.1016/j.tws.2013.08.012.
dc.relation.haspart [Publication 3]: Jelovica, Jasmin; Romanoff, Jani; Ehlers, Sören; Aromaa, Jari. Ultimate strength of corroded web-core sandwich beams. Marine Structures, volume 31, pages 1-14, 2013. doi:10.1016/j.marstruc.2012.12.001.
dc.relation.haspart [Publication 4]: Jelovica, Jasmin; Romanoff, Jani; Remes, Heikki. Influence of general corrosion on buckling strength of laser-welded web-core sandwich plates. Journal of Constructional Steel Research, volume 101, pages 342-350, 2014. doi:10.1016/j.jcsr.2014.05.025.
dc.subject.other Marine engineering en
dc.title Global buckling response of web-core steel sandwich plates influenced by general corrosion en
dc.type G5 Artikkeliväitöskirja fi Insinööritieteiden korkeakoulu fi School of Engineering en
dc.contributor.department Sovelletun mekaniikan laitos fi
dc.contributor.department Department of Applied Mechanics en
dc.subject.keyword buckling en
dc.subject.keyword post-buckling en
dc.subject.keyword sandwich plate en
dc.subject.keyword corrosion en
dc.subject.keyword steel en
dc.subject.keyword web-core en
dc.subject.keyword equivalent single-layer en
dc.identifier.urn URN:ISBN:978-952-60-5861-0
dc.type.dcmitype text en
dc.type.ontasot Doctoral dissertation (article-based) en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.contributor.supervisor Romanoff, Jani, Prof., D.Sc. (Tech.), Aalto University, Department of Applied Mechanics, Finland
dc.opn Guedes Soares, Carlos, Prof., University of Lisbon, Portugal 2014-08-18
dc.contributor.lab Marine Technology en
dc.contributor.lab Meritekniikka fi
dc.rev Shenoi, R. Ajit, Prof., University of Southampton, United Kingdom
dc.rev Rigo, Philippe, Prof., University of Liege, Belgium 2014-11-06

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