Subjects of the current thesis are the study of sloshing phenomenon in upright cylindrical containers and its 3D finite element modelling with the software Abaqus/CAE. In particular, both analytical models which can be traced in literature, such as in the book ‘Liquid Sloshing Dynamics – Theory and Application’ written by R. Ibrahim, and EC8 prescriptions for the analysis of sloshing phenomenon in rigid and deformable tanks subject to seismic motion have been described and implemented. EC8 provides a set of requirements for general and simplified procedures to model the sloshing phenomenon depending on the typology of the tank’s structure (rigid or deformable) and on the considered seismic action component. For these reasons, four analytical models were implemented for non-linear dynamics analyses (two for rigid tanks and two for deformable ones, a refined procedure and a simplified one are included in both models), plus one for static analyses according to EC3 – Part 4-2: Tanks. Regarding numerical analyses, different 3D finite element models were developed with the usage of the software Abaqus/CAE according to the typology of analysis (linear static, modal and non-linear dynamic). Two principal models were considered for dynamics analyses (the first for rigid containers, the latter for deformable ones): for each of these two models, seven seismic inputs corresponding to seven artificial spectrum-compatible accelerograms, which were created with the usage of the software SIMQKE, were introduced. The purpose of the considered analyses (both analytical and numerical) is to assess the response of a cylindrical container filled with water subject to seismic motion and to study the influence of the sloshing phenomenon over the structure in terms of base resultants as shear force and bending moment. For this reason, a set of different comparison was proposed to verify the reliability of the 3D finite element model. During the modelling phase of the fluid, a specific approach able to catch the sloshing response correctly was considered. Particular attention was dedicated to the definition of the fluid properties, of the tank-fluid interaction and to the choice of an adequate element to assign to the mesh. The object of these analyses is a simplified model representing the last available layout of a dark matter particles detector provided by ‘Istituto Nazionale di Fisica Nucleare’ (INFN) to ‘Politecnico di Milano’. The structure belongs to the family of ‘DarkSide’ particles detector, it is an updated version of the first detector called DarkSide-50, and it will be built in ‘Gran Sasso National Laboratory’ (LNGS). The international project, DarkSide-20k, involved not only INFN and LNGS but also ‘Politecnico di Milano’ and other worldwide universities. In the current project, only a simplified version of the external part of the dark matter detector is considered, that means the external cylindrical tank filled with ultrapure water functioning as an active muon veto. Inside the tank, an active neutron veto filled with boron-loaded liquid scintillator (LSV) is present, which contains a two-phase liquid-argon time-projection chamber (TPC) for WIMP detection.
Gli argomenti trattati nel seguente elaborato di tesi riguardano lo studio del fenomeno di sloshing in serbatoi cilindrici verticali e la sua modellazione 3D ad elementi finiti mediante l’utilizzo del software Abaqus/CAE. In particolare, sono stati descritti e implementati sia modelli analitici rintracciabili in letteratura, come nel libro ‘Liquid Sloshing Dynamics – Theory and Application’scritto da R. Ibrahim, sia prescrizioni dell’Eurocodice 8 per l’analisi del fenomeno di sloshing in serbatoi rigidi e deformabili soggetti ad azione sismica. L’EC8 fornisce una serie di requisiti per procedure di analisi generali e semplificate per la modellazione del fenomeno di sloshing; essi dipendono dalla tipologia di struttura del serbatoio (rigido o deformabile) e dalla componente di azione simica considerata. Per questi motivi, quattro modelli analitici sono stati implementati per analisi dinamiche non lineari (due per serbatoio rigido e due per serbatoio deformabili, entrambi comprendenti una procedura più accurata e una semplificata), più uno per le analisi statiche in accordo con EC3 – Part 4-2: Tanks. Per quanto riguarda le analisi numeriche, differenti modelli 3D ad elementi finiti sono stati implementati mediante il software Abaqus/CAE a seconda del tipo di analisi (statica, modale, dinamica non-lineare). Sono stati considerati due modelli principali per le analisi dinamiche (uno per serbatoi rigidi, l’altro per serbatoi deformabili): per ciascuno dei due modelli sono stati introdotti sette input sismici differenti in relazione ad altrettanti accelerogrammi artificiali spettro-compatibili creati mediante il software SIMQUE. Lo scopo delle analisi effettuate (analitiche e numeriche) è quello di valutare la risposta di un serbatoio cilindrico riempito parzialmente da un fluido quando soggetto ad azione sismica, studiando l’influenza che il fenomeno di sloshing ha sulla struttura in relazione alle risultanti alla base del serbatoio, in termini di taglio e momento flettente. A tal fine, sono stati proposti differenti confronti per verificare la bontà del modello ad elementi finiti. Durante la fase di modellazione ad elementi finiti del fluido è stato considerato un approccio specifico e tale da poter cogliere correttamente la risposta allo sloshing. Particolare attenzione è stata dedicata alla definizione delle proprietà del fluido, all’interazione fluido-struttura e alla scelta della tipologia di elemento da assegnare alla mesh. L’oggetto di studio è un modello semplificato rappresentante l’ultimo layout disponibile di un rilevatore di particelle di materia oscura fornito dall’‘Istituto di Fisica Nucleare’ (INFN) al ‘Politecnico di Milano’. La struttura appartiene alla famiglia di rilevatori di particelle denominati ‘DarkSide’, corrisponde a una versione aggiornata del primo rilevatore di particelle, DarkSide-50, e sarà costruito presso i ‘Laboratori Nazionali del Gran Sasso’ (LNGS). Il progetto internazionale DarkSide-20k coinvolge, oltre a INFN e LNGS, anche il ‘Politecnico di Milano’ ed altre università e laboratori a livello mondiale. Nel progetto corrente solamente una versione semplificata della parte esterna del rilevatore di particelle è stata considerata, ossia il serbatoio cilindrico esterno riempito con acqua ultrapura con funzione di veto per i muoni. All’interno del serbatoio è presente un veto per neutroni costituito da scintillatore liquido borato (LSV), all’interno del quale è inserita una camera a proiezione temporale (TPC) bifasica ad Argon per la rilevazione di WIMP.
Sloshing phenomenon in cylindrical vertical tanks : numerical analyses and comparison with Eurocode
FILIBERTI, CHIARA
2016/2017
Abstract
Subjects of the current thesis are the study of sloshing phenomenon in upright cylindrical containers and its 3D finite element modelling with the software Abaqus/CAE. In particular, both analytical models which can be traced in literature, such as in the book ‘Liquid Sloshing Dynamics – Theory and Application’ written by R. Ibrahim, and EC8 prescriptions for the analysis of sloshing phenomenon in rigid and deformable tanks subject to seismic motion have been described and implemented. EC8 provides a set of requirements for general and simplified procedures to model the sloshing phenomenon depending on the typology of the tank’s structure (rigid or deformable) and on the considered seismic action component. For these reasons, four analytical models were implemented for non-linear dynamics analyses (two for rigid tanks and two for deformable ones, a refined procedure and a simplified one are included in both models), plus one for static analyses according to EC3 – Part 4-2: Tanks. Regarding numerical analyses, different 3D finite element models were developed with the usage of the software Abaqus/CAE according to the typology of analysis (linear static, modal and non-linear dynamic). Two principal models were considered for dynamics analyses (the first for rigid containers, the latter for deformable ones): for each of these two models, seven seismic inputs corresponding to seven artificial spectrum-compatible accelerograms, which were created with the usage of the software SIMQKE, were introduced. The purpose of the considered analyses (both analytical and numerical) is to assess the response of a cylindrical container filled with water subject to seismic motion and to study the influence of the sloshing phenomenon over the structure in terms of base resultants as shear force and bending moment. For this reason, a set of different comparison was proposed to verify the reliability of the 3D finite element model. During the modelling phase of the fluid, a specific approach able to catch the sloshing response correctly was considered. Particular attention was dedicated to the definition of the fluid properties, of the tank-fluid interaction and to the choice of an adequate element to assign to the mesh. The object of these analyses is a simplified model representing the last available layout of a dark matter particles detector provided by ‘Istituto Nazionale di Fisica Nucleare’ (INFN) to ‘Politecnico di Milano’. The structure belongs to the family of ‘DarkSide’ particles detector, it is an updated version of the first detector called DarkSide-50, and it will be built in ‘Gran Sasso National Laboratory’ (LNGS). The international project, DarkSide-20k, involved not only INFN and LNGS but also ‘Politecnico di Milano’ and other worldwide universities. In the current project, only a simplified version of the external part of the dark matter detector is considered, that means the external cylindrical tank filled with ultrapure water functioning as an active muon veto. Inside the tank, an active neutron veto filled with boron-loaded liquid scintillator (LSV) is present, which contains a two-phase liquid-argon time-projection chamber (TPC) for WIMP detection.| File | Dimensione | Formato | |
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2017_12_Filiberti.pdf
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https://hdl.handle.net/10589/138187