Procjena zamora zavarene konstrukcije hidrogeneratora

professional thesis

• Author: Monika Pižeta
• Mentor: Zdenko Tonković (mentor)
• Committee member: Ivica Skozrit (predsjednik povjerenstva)
• Committee member: Zdenko Tonković (član povjerenstva)
• Committee member: Mladen Meštrović (član povjerenstva)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2019-11-15, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Tvrtka Končar – Generatori i motori d.d obavlja revitalizaciju hidroelektrane Puntarikoski u
Finskoj. U sklopu revitalizacije, većina glavnih dijelova hidrogenertora se ne zamjenjuje s
novim dijelovima. S obzirom da su neki dijelovi hidrogeneratora u primjeni više od 50 godina,
potrebno ih je ponovo mehanički proračunati s naglaskom na zamorni integritet i vijek
trajanja.
U ovom radu, napravljena je procjena zamornog integriteta i vijeka trajanja za zavarenu
konstrukciju hidrogeneratora, točnije zvijezdu rotora hidrogeneratora, za ciklus opterećenja
s nazivne brzine vrtnje na teoretski pobjeg (maksimalna brzina koja se javlja u radu
hidrogeneratora). Prije nego što se napravila procjena za zvijezdu rotora hidrogeneratora,
potvrđena je ispravnost korištenja programskog paketa Autodesk Simulation Mechanical uz
primjenu FKM priručnika na jednostavnijem primjeru dviju međusobno zavarenih ploča.
Postupak procjene sastoji se od dva koraka: izrade numeričkog modela korištenjem
programskog paketa Autodesk Simulation Mechanical i primjene FKM priručnika. FKM
priručnik nudi dva pristupa procjene, globalni i lokalni, uz mogućnost izračuna za nezavarene
i zavarene konstrukcijske elemente. Globalni pristup podrazumijeva pristup nominalnog
naprezanja, dok lokalni podrazumijeva pristup žarišnog ili zareznog naprezanja.
Procjena zvijezde rotora hidrogeneratora napravljena je za sva tri pristupa naprezanja. Uz to,
obuhvatila je i izračun za nezavarene i zavarene konstrukcijske elemente uz pomoć dva
numerička modela zvijezde rotora hidrogeneratora koji se razlikuju samo po modeliranim
zavarima na mjestima najvećih naprezanja. Na taj način, dobivena je usporedba navedenih
pristupa naprezanja te u skladu s tim i unapređenje izračuna zamornog integriteta i vijeka
trajanja hidrogeneratorskih dijelova.

Abstract (english)

Končar – Generators and Motors Inc. is carrying out renovations of the Puntarikoski
hydroelectric power plant in Finland. As part of this revitalization, most of the main
components of the hydrogenerator are not replaced with new parts. However, because
some parts of the hydrogenerator have been in use for more than 50 years, they must be
mechanically re-calculated especially with regards to fatigue integrity and lifetime.
In this thesis, fatigue integrity and lifetime were assessed for a welded construction of a
hydrogenerator, more precisely, the rotor spider of the hydrogenerator, during the load
cycle from nominal speed to runaway speed (the maximum speed that occurs during
operation). Before assessing the rotor spider of the hydrogenerator, the validity of the
software package Autodesk Simulation Mechanical while observing the FKM guideline, was
confirmed on a simpler example of two mutually welded plates.
The assessment procedure consists of two steps: creating a numerical model using the
software package Autodesk Simulation Mechanical, and application of the FKM guideline.
The FKM guideline offers two assessment approaches, global and local, and the ability to
calculate for non-welded and welded construction elements. The global approach
encompasses nominal stress, while the local approach comprises hot spot stress or effective
notch stress.
The assessment of the rotor spider of hydrogenerator was made for all three stress
approaches. It also included calculations of both non-welded and welded construction
elements, with the help of two numerical models of the hydrogenerator’s rotor spider,
which differ only by modeled welds at the highest stress sites.
In this way, a comparison of these stresses was obtained, as were improved calculations of
fatigue integrity and lifetime of hydrogenerator parts.

• Keywords: hidrogenerator; zvijezda rotora hidrogeneratora; zamor materijala; zamor zavarenog materijala; FKM priručnik; pristup nominalnog naprezanja; pristup žarišnog naprezanja; pristup zareznog naprezanje; Autodesk Simulation Mechanical; metoda konačnih elemenata
• Keywords (english): hydrogenerator; rotor spider of hydrogenerator; material fatigue; fatigue of welded material; FKM guideline; nominal stress approach; hot spot stress approach; effective notch stress approach; Autodesk Simulation Mechanical; finite element method
• Language: croatian
• URN:NBN: urn:nbn:hr:235:499419
• Study programme: Title: Mechanical Engineering and Naval Architecture - specialist; Study programme type: university; Study level: postgraduate specialist; Academic / professional title: sveučilišni/a specijalist/specijalistica strojarstva i brodogradnje (sveučilišni/a specijalist/specijalistica strojarstva i brodogradnje)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-01-28 13:07:45