Nonlinear finite element modeling of shells for multiscale analysis applications

Μη Γραμμική ανάλυση κελυφών με εφαρμογές στην ανάλυση πολλαπλών κλιμάκων. (EL)

Nonlinear finite element modeling of shells for multiscale analysis applications (EN)

Sotiropoulos, Gerasimos (EL)

Σωτηρόπουλος, Γεράσιμος (EN)

Παπαδόπουλος, Βησσαρίων

Νεραντζάκη, Μαρία (EL)

ntua (EL)

Σπηλιόπουλος, Κωνσταντίνος (EL)

Τριανταφύλλου, Σάββας (EL)

Γαντές, Χαράλαμπος (EL)

Κουμούσης, Βλάσιος (EL)

Φραγκιαδάκης, Μιχαήλ (EL)

Παπαδόπουλος, Βησσαρίων (EL)

doctoralThesis

2021-09-29T09:35:03Z

2021-05-21

In this thesis a formulation for multi-scale analysis of thin shells is presented. It is based on the first order homogenization theory and it allows for modeling, in a FE2 method's context, of thin shells that meet the Kirchhoff Love hypothesis. The shells exhibit a heterogeneous micro-structure consisting of nonlinear materials and cohesive interfaces that periodically repeats itself in the in plane and out of plane direction of the shell with respect to its mid-surface. The proposed methodology is then extended to shell structures that may undergo large deformations and strains and the same hypotheses are exploited for the periodicity of their heterogeneities and their size scale. Appropriate use of an attached coordinate system for the transformation of the utilized strain measures enables the neutralization of the moderately large rotations’ effect on the implementation of constraints at the RVE level, simplifying this way the boundary value problem to be solved at the micro-structural level. Emanating from Hill's averaging theorem, which is satisfied by use of appropriated averaging relations for thin shells, the principle of virtual work for thin Kirchhoff Love shells is formulated to account for those transformations and the expression of a consistent Stiffness Matrix is analytically derived. The proposed methodology is assessed against popular benchmarks for thin shells and its applicability is demonstrated in virtual testing of thin nanocomposite structures. Next the mechanical behavior of graphene reinforced nanocomposite structures is studied in a first order homogenization context. A simplified thin shell homogenization approach is followed for the modeling of graphene sheets with equivalent shell elements and a cohesive zone finite element model is utilized for modeling of the polymer graphene interaction. The effect of various characteristics of the micro structure such as the strength of the cohesive zone and geometry defects of the graphene sheets on the overall properties of the nanocomposite are under study. (EN)

Ανάλυση φορέων σε πολλαπλές κλίμακες (EL)

Ετερογενή υλικά (EL)

Κελύφη (EL)

Ανάλυση φορέων Με πεπερασμένα στοιχεία (EL)

Λυγισμός (EL)

Finite element analysis (EN)

Shells (EN)

Heterogeneous materials (EN)

Multiscale Analysis (EN)

Buckling (EN)

Greek

English

Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Πολιτικών Μηχανικών. Τομέας Δομοστατικής. Εργαστήριο Στατικής και Αντισεισμικών Ερευνών (EL)

Αναφορά Δημιουργού-Μη Εμπορική Χρήση-Όχι Παράγωγα Έργα 3.0 Ελλάδα

http://creativecommons.org/licenses/by-nc-nd/3.0/gr/

National Technical University of Athens

Digital Library of National Technical University of Athens | Dspace@NTUA

Κεντρική Βιβλιοθήκη Ε.Μ.Π.

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