Numerički proračun naprezanja u posudi pod tlakom pomoću metode konačnih elemenata

master's thesis

• Title (english): Numerical calculation of stresses in pressure vessel by Finite Element Method
• Author: Davor Volarić
• Mentor: Tomislav Jarak (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2017-03-31, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

Tema ovog rada je numerički proračun naprezanja u posudi pod tlakom pomoću metode konačnih elemenata. Svi proračuni metodom konačnih elemenata prikazani u radu napravljeni su u programskom paketu Abaqus. Posuda je uz opterećenje unutarnjim tlakom opterećena i vanjskim mehaničkim opterećenjima. U sklopu rada proveden je kontrolni proračun svih komponenata posude pod tlakom pomoću ASME norme. ASME norma sadrži pravila za proračun posude opterećene samo unutarnjim i/ili vanjskim tlakom, a za kontrolu naprezanja do kojih dolazi uslijed vanjskih mehaničkih opterećena dopuštena je primjena metode konačnih elemenata. Prije samog numeričkog proračuna objašnjene su metode i tehnike modeliranja dostupne u programskom paketu Abaqus, te je na jednostavnim primjerima izvršena verifikacija konačnih elemenata i tehnika modeliranja koji su korišteni pri proračunu posude. Nakon toga je provedena numerička analiza čvrstoće posude za dva slučaja opterećenja koji se javljaju tijekom rada posude. Cijela konstrukcija diskretizirana je pomoću trodimenzijskih volumnih elemenata. Primjećeno je da se na mjestima spojeva ukruta i prirubnica javljaju velike koncentracije naprezanja. Područje s najvišom koncentracijom naprezanja detaljnije je analizirano upotrebom tehnike podmodeliranja. Utvrđeno je da su na mjestima koncentracije naprezanja maksimalna naprezanja viša od dopuštenih te je predloženo rješenje za preoblikovanje kritičnih dijelova konstrukcije kako bi se smanjila koncentracija naprezanja.

Abstract (english)

The subject of this thesis is stress calculation in a pressurised vessel utilizing the Finite Element Method. All numerical computations are performed by using the program package Abaqus. Alongside the internal pressure load, the vessel is also loaded by external mechanical loads. Within the scope of the thesis, the control stress calculations of all of the vessel's components are performed in accordance with the ASME norm. The ASME norm encompasses all rules concerning calculations of vessels loaded only by internal and/or external pressure, whilst for the calculation of stresses resulting from external mechanical loads the application of Finite Element Method is permitted. Prior to the actual numerical calculation, modelling methods and techniques available within the Abaqus software package are presented, and finite element types and modelling methods utilised for the actual calculations of the vessel are verified on appropriate simple examples. Thereafter, the numerical analysis of the vessel's mechanical strength is carried out, whereby two load cases occurring during the operation conditions are considered. For the purpose of stress analysis, the entire structure is modelled by the three-dimensional continuum elements. It has been established that high stress concentration occurs at the joints of stiffeners and flanges. The stresses in the region with the highest stress concentration is analysed in more details by using the sub-modelling technique. It has been found out that the stresses at that spot are higher than the allowable stresses, and a redesign of the regions with high stress concentrations is proposed.

• Keywords: Abaqus; posuda pod tlakom; ASME norma; metoda konačnih elemenata; podmodeliranje
• Keywords (english): Abaqus; pressure vessel; ASME norm; Finite Element Method; sub-modeling
• Language: croatian
• URN:NBN: urn:nbn:hr:235:968532
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 19:28:06