Numerički proračun čvrstoće horizontalnog tlačnog spremnika za plin

undergraduate thesis

• Title (english): Numerical stress analysis of horizontal gas pressure tank
• Author: Igor Grabar
• Mentor: Tomislav Jarak (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2016-09-22, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

Tlačni spremnici su zatvoreni kontejneri koji su korišteni za skladištenje plinova ili kapljevina pod tlakom koji se bitno razlikuje od okolišnog. Danas predstavljaju jedan od najbitnijih oblika skladištene energije. Zbog visokih tlakova unutar spremnika imamo vrlo visoke kriterije sigurnosti čvrstoće i krutosti samih konstrukcija.

Prije proračuna samog tlačnog spremnika objašnjene su numeričke metode koje se koristite kod analize. Osim toga ukratko su opisani korišteni konačni elementi kod verifikacijskih primjera i samog proračuna spremnika. Nakon toga opisana je tehnika podmodeliranja koju koristimo pri detaljnijoj analizi lokalnih dijelova konstrukcije. Kod prvog verifikacijskog primjera uspoređuju se trokutni i četverokutni ljuskasti elementi prvog i drugog stupnja proučavajući pri tome konvergenciju njihovih rješenja prema prije izračunatom analitičkom rješenju za pravokutnu ploču opterećenu površinskim tlakom. Kod drugog verifikacijskog zadatka uspoređujemo analitičko rješenje za spremnik vode s rješenjima koja su dobivena numeričkim proračunom i to korištenjem ljuskastih elemenata, 3D elemenata te podmodeliranja. Treći verifikacijski primjer sastoji se od analize tlačne posude pri čemu analitičko rješenje uspoređujemo s rješenjima dobivenim korištenjem ljuskastih elemenata i podmodeliranja.

Proračun horizontalnog spremnika započinjemo analitičkim određivanjem potrebne debljine stjenke. Korištenjem ljuskastih četverokutnih elemenata drugoga reda izrađujemo model spremnika pomoću kojega provjeravamo ranije izračunatu debljinu stjenke. Ta se debljina po potrebi mijenja. Osim debljine same stjenke mijenjamo i ostale dimenzije spremnika kako bi dobili konstrukciju zadovoljavajuće čvrstoće. Nakon toga na kritična mjesta postavljamo ukrute i tehnikom podmodeliranja provjeravamo njihovu čvrstoću te čvrstoću područja oko njih. Nakon toga, zadajemo dimenzije oslonaca koje provjeravamo i prema potrebi mijenjamo dok ne zadovoljimo čvrstoću istih pritom koristeći heksagonalne prizmatične elemente drugoga stupnja. Konačno, korištenjem tehnike spajanja ljuskastih i 3D elemenata („Shell to solid coupling“) provjeravamo čvrstoću priključka spremnika i samog spremnika. Svi numerički postupci su iterativni i ponavljaju se dok se ne dobiju dimenzije koje zadovoljavaju čvrstoću.

Abstract (english)

Gas pressure tanks are closed containers that are used for storing gases or liquids that are under pressure which is substantially different from the enviromental one. Today they represent one of the most important forms of stored energy. Due to the very high pressures inside the tank there is a high level of strength safety and stiffness of the constructions themselves.

Prior to the calculation of the pressure vessel numerical methods used in the analysis are explained. Additionally, finite elements which were used in verification examples and in the analysis of the tank were briefly described. After that the techniques that we use in the detailed analysis of local structural parts were explained. In the first verification example the triangular and rectangular shell elements of the first and second degree were compared while studying the convergence of their solutions based on the previously computed analytical solution for rectangular plate loaded with surface pressure. In the second verification task the analytical solution for the water tank was compared with the solutions that had been obtained by numerical analysis through the use of shell elements, 3D elements and the submodeling technique. The third verification example consists of the analysis of the pressure vessel while comparing the analytical solution with the solutions obtained through the use of shell elements and the submodeling technique.

Analysis of the horizontal tank begins with the analytical assignment of the necessary shell thickness. The model of the container is made by using the shell quadrilateral elements of the second order which is needed to perform an analysis of the before computed thickness. The thickness is varied according to the strength condtioin. Except to the thickness, other dimensions are changed in order to obtain the needed strength of the construction. After that, the reinforcements are set on the critical places and by using the submodeling technique their strength is verified. Furthermore, it is necessary to specify the dimensions of the supports that are verified by using hexagonal prismatic elements of the second degree and, if necessary, they are changed until their strength is satisfied. Finally, by using the shell and 3D elements joining technique ("Shell to solid coupling"), the strength of the connection of the tank and the tank itself is verified. All of the numerical procedures are iterative and they are performed until the dimensions that satisfy the strength condition are obtained.

• Keywords: Abaqus; metoda konačnih elemenata; tlačni spremnik; podmodeliranje; shell to solid coupling
• Keywords (english): Abaqus; Finite Element Method; pressure tank; submodeling; shell to solid coupling
• Language: croatian
• URN:NBN: urn:nbn:hr:235:963602
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 17:46:17