dc.contributor.author | Γεωργίου, Δεσποινα | el |
dc.contributor.author | Georgiou, Despina | en |
dc.date.accessioned | 2020-01-21T09:39:52Z | |
dc.date.available | 2020-01-21T09:39:52Z | |
dc.identifier.uri | https://dspace.lib.ntua.gr/xmlui/handle/123456789/49700 | |
dc.identifier.uri | http://dx.doi.org/10.26240/heal.ntua.17398 | |
dc.description | Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Ναυτική και Θαλάσσια Τεχνολογία και Επιστήμη” | el |
dc.rights | Αναφορά Δημιουργού-Όχι Παράγωγα Έργα 3.0 Ελλάδα | * |
dc.rights.uri | http://creativecommons.org/licenses/by-nd/3.0/gr/ | * |
dc.subject | Buckling | en |
dc.subject | Torsion | en |
dc.subject | Finete element analysis | en |
dc.subject | Stiffeners | en |
dc.subject | Aabaqus | en |
dc.title | Buckling and ultimate strength of stiffened panels | en |
dc.contributor.department | Marine Technology | el |
heal.type | masterThesis | |
heal.generalDescription | Present Rules given by Classification Societies (IACS) give rational criteria for dimensioning the hull structure ensuring sufficient strength for safe operations. However, the ship designers/yards are in fierce competition and by offering reduced steel weight, possible increased cargo capacity and reduce fuel consumption can be achieved. This business pressure leads to creative thinking among designers and more optimal and thinner structures are the result. For extreme loads this again will challenge the structural capacity limits and unwanted “overload” damages and permanent sets may be the result. Safe Rule scantlings are mainly determined by stress and buckling criteria such as given in DNV GL Ship Rules. They are typically based on text book formulas (Euler, etc.) modified to take into consideration different buckling modes, interactions between elements, non-linear behaviour, combined bi-axial/shear loads acting, etc. These types of Rule models are termed Closed Form Method (CFM) and covers basically all relevant failure modes. Though, some of these CFM models have limitations, and improvements/extensions are needed to provide for more consistent dimensioning for some designs. The most advanced approach is to use non-linear FE tools (Abaqus or equivalent). Such models are expensive and time consuming to analyse and not much used in normal ship design work unless the case requires special documentation. However, such models are very valuable for benchmarking simpler buckling models. The task of the master thesis work is to assess existing buckling models of stiffened plate as proposed by DNV GL and develop new and improved models where found necessary. The buckling/failure modes to be considered are torsional buckling of different types of stiffener sections and global (overall) buckling of stiffened panels. The approach used for solving the overall task will constitute a combination of analytical work and numerical analyses using non-linear FE tool. Analytical work will be needed in relation to derivation of closed formed buckling models and proposal of approximations while numerical buckling analyses (Abaqus) will be used for validating the simpler formulas (CFM) The work rreviews and summarizes the DNV GL (IACS) Rules, as relevant for the two buckling modes to be considered. Additionally, numerical comparison studies (Abaqus) were carried out for validating the CFM predictions given above. Two levels of validation achieved. The first refers to the comparison of eigenvalues and the second, on ultimate capacity over a relevant parameter span as typical for ship designs (vary stiffener lengths, plate thickness, etc.). Finally, alternative models were improved or developed for eigenvalues for torsional and overall buckling strength. | en |
heal.classification | Structural Analysis | en |
heal.language | en | |
heal.access | free | |
heal.recordProvider | ntua | el |
heal.publicationDate | 2019-09-13 | |
heal.abstract | Thin plates are structural elements that are widely used in many engineering fields, such as aerospace, shipbuilding and civil engineering. Ribbed and stiffened ship plates, offshore, and aerospace panels are commonly utilized and always subjected to partial edge traction on their own plane. This type of loading can induce buckling, which negatively affects the function of the structural elements concerned. Plate instability is generated globally or locally through in plane compression and lateral loading. The corrugations resulting from plate instability may cause permanent deformations and reduce the efficiency of the entire structure. The project focuses on buckling and ultimate strength of stiffened panels. Torsional buckling of the stiffeners, plate local buckling as well as overall buckling of stiffened panels will be examined. During the assessment of their structural responses, both numerical and analytical methods will be implemented. | en |
heal.sponsor | 6-month Erasmus project | en |
heal.advisorName | Σαμουηλίδης, Μανώλης | en |
heal.advisorName | Jorgen, Amdahl | el |
heal.committeeMemberName | Σαμουηλίδης, Μανώλης | en |
heal.committeeMemberName | Jorgen, Amdahl | el |
heal.committeeMemberName | Ανιφαντής, Κωνσταντίνος | el |
heal.academicPublisher | Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Ναυπηγών Μηχανολόγων Μηχανικών | el |
heal.academicPublisherID | ntua | |
heal.numberOfPages | 81 σ. | el |
heal.fullTextAvailability | true |
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