Zamorna izdržljivost konstrukcijskih detalja na LNG brodovima s membranskim tankovima

master's thesis

• Title (english): Fatigue strength of structural details on LNG ships with membrane tanks
• Author: Dominik Banjedvorec
• Mentor: Smiljko Rudan (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2023-07-17, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Shipbuilding; Constructive of Floating and Maritime Structures

Abstract

U kontekstu sve veće energetske potrebe, LNG brodovi su postali ključni u prijevozu
energenata. Međutim, gradnja suvremenih LNG brodova uključuje izradu nestandardnih
strukturnih detalja koji su često povezani s povećanim rizikom od zamornog oštećenja. U radu
je prikazan pojednostavljeni proračun zamornog oštećenja u LNG brodova s membranskim
tipom spremnika. Izrađen je globalni model veličine od 3 spremnika te je model bilo potrebno
balansirati kako bi se dobila realna distribucija smičnih sila i momenata na spremniku za koji
se radio proračun, u ovom slučaju spremnik broj 3. Od opterećenja u pojednostavljenom
proračunu uzeti su hidrostatički tlak, te hidrodinamički tlak i ubrzanja koja proizlaze iz valnog
opterećenja u kojemu je smjer vala u pramac broda. Provedena su dva postupka ekstrapolacije
kvadratna i linearna ekstrapolacija žarišnih naprezanja s podmodela koji su dodatno izrađeni.
Na osnovi tih naprezanja i propisane S-N krivulje izračunato je zamorno oštećenje
konstrukcijskog detalja na LNG brodu.

Abstract (english)

In the context of increasing energy demand, LNG (liquefied natural gas) ships have become
crucial in energy transportation. However, the construction of modern LNG ships involves the
fabrication of non-standard structural details that are often associated with an increased risk of
fatigue damage. This paper presents a simplified fatigue analysis for LNG ships with
membrane-type tanks. A global model consisting of three tanks was developed, and the model
had to be balanced to obtain a realistic distribution of shear forces and moments on the tank
under consideration, in this case, tank number 3. The simplified fatigue analysis considered
loading conditions such as hydrostatic pressure, hydrodynamic pressure, and accelerations
resulting from wave loading, with the wave direction directed towards the bow of the ship.
Two extrapolation methods, quadratic and linear extrapolation of hot spot stresses from sub-
models, were performed. Based on these stresses and the prescribed S-N curve, the fatigue
damage of the structural detail on the LNG ship was calculated.

• Keywords: Analiza tri skladišta; balansiranje modela; žarišna naprezanja; pojednostavljen proračun; zamorno oštećenje
• Keywords (english): Three cargo hold analysis; balancing of the model; hot spot stress; simplified fatigue analysis; fatigue damage
• Language: croatian
• URN:NBN: urn:nbn:hr:235:424313
• Study programme: Title: Naval Architecture; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka brodogradnje (magistar/magistra inženjer/inženjerka brodogradnje)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-07-10 11:46:28