Numerička analiza hidrauličkog akumulatora s mijehom

master's thesis

• Title (english): Numerical analysis of a hydraulic bladder accumulator
• Author: Ilija Jurič
• Mentor: Ivica Skozrit (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2020-05-15, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

Cilj ovog rada je provesti numeričku analizu hidrauličkog akumulatora s mijehom (opnom) i provjeriti zadovoljava li on uvjet čvrstoće. Numerička analiza provedena je u programskom paketu Abaqus, proizvodu tvrtke Dassault Systèmes, a koji se temelji na metodi konačnih elemenata. U uvodnom dijelu rada navedeni su zadaci hidrauličkih akumulatora, njihova podjela i glavne karakteristike, te je objašnjen njihov princip rada. Nakon toga rečeno je nešto o metodi konačnih elemenata i o samim elementima koji su korišteni tijekom rada, a to su ljuskasti, osnosimetrični i elementi za trodimenzijsku analizu. Nakon prva dva teoretska poglavlja, proračunski dio rada započinje se verifikacijom konačnih elemenata, gdje se razmatra primjer sličan glavnom problemu, a za koji se bez previše poteškoća može doći do analitičkog rješenja (a isto tako i numeričkog). Pri tome se usporedbom numeričkih rezultata i analitičkog rješenja zaključuje koji podtipovi navedena tri tipa konačnih elemenata najbolje konvergiraju, odnosno daju najbrže približavanje analitičkom rješenju povećavanjem njihovog broja. Kao varijabla koja se razmatra za konvergenciju uzet je maksimalni radijalni pomak. U posljednjem, 4. poglavlju, prvo je ukratko rečeno nešto o samoj konstrukciji hidrauličkog akumulatora s mijehom i na koji će se način ona pojednostaviti za analizu, te su definirani potrebni podaci za proračun. Nakon toga prelazi se na glavni dio rada, tj. analitički i numerički proračun akumulatora, gdje se prikazuje konvergencija maksimalnog radijalnog pomaka i maksimalnog ekvivalentnog naprezanja te se utvrđuje zadovoljava li akumulator uvjet čvrstoće i s kojim faktorom sigurnosti. Prikazuju se i dijagrami raspodjele radijalnog pomaka te cirkularnog i meridijalnog naprezanja. U numeričkoj analizi, na osnovu prethodne verifikacije, koriste se elementi koji najbolje konvergiraju, a rezultati se uspoređuju s analitičkim rješenjima i zaključuje se kakvo je njihovo poklapanje.

Abstract (english)

The aim of this paper is to perform a numerical analysis of a bladder hydraulic accumulator and to verify that it meets the strength requirement. The numerical analysis was carried out in the Abaqus software package, a product of Dassault Systèmes, which is based on the finite element method. In the introductory part of the paper the tasks of hydraulic accumulators, their division and main characteristics are stated and their principle of operation is explained. After that, a word has been said about the finite element method and the elements that were used during the analysis, namely shell, axisymmetric and elements for three-dimensional analysis. After the first two theoretical chapters, calculation part of the paper begins with the verification of finite elements, where an example similar to the main problem is considered, and for which an analytical solution (and also a numerical one) can be obtained without too much difficulty. By comparing the numerical results and the analytical solution, it is concluded which subtypes of the three types of finite elements converge best, that is, give the fastest approximation to the analytical solution when increasing their number. The maximum radial displacement was chosen as the variable for convergence. In the last, fourth chapter, it is first briefly said about the design of a bladder accumulator and how it will be simplified for analysis, and also the necessary data for the calculation are defined. After that comes the main part of the work which is analytical and numerical calculation of the accumulator where the convergence of maximum radial displacement and maximum equivalent stress is shown and where is determined whether the accumulator satisfies the strength requirement and with what factor of safety. The graphs of the distribution of radial displacement and circular and meridional stresses are also shown. In the numerical analysis, based on the previous verification, the elements that converge best are used, and the results are compared with the analytical solutions and it is concluded how good their match is.

• Keywords: hidraulički akumulator; numerička analiza; Abaqus; konačni elementi; verifikacija; analitički proračun; konvergencija; pomak; naprezanja
• Keywords (english): hydraulic accumulator; numerical analysis; Abaqus; finite elements; verification; analytical calculation; convergence; displacement; stresses
• Language: croatian
• URN:NBN: urn:nbn:hr:235:394447
• 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: 2020-05-08 14:27:28