Numeričko modeliranje procesa elasto-plastičnog deformiranja u mikrostrukturi sinteriranog čelika

master's thesis

• Title (english): Numerical modelling of elasto-plastic deformation processes in the microstructures of sintered steel
• Author: Božidar Jolić
• Mentor: Tomislav Jarak (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2020-12-04, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

Pojava nove, ali izuzetno važne grane moderne industrije, industrije metalurgije praha u današnjem svijetu sve se više nameće kao potreba zbog svoje brzine izrade pojedinih komponenti. Proizvodi od sinteriranog metala dobiveni metalurgijom praha uspješno zamjenjuju one dobivene klasičnijim metodama poput lijevanja ili kovanja čelika već dugi niz godina. To je prije svega uvjetovano značajnim smanjenjem proizvodnih troškova, točnosti izrade, glatkoći površina itd.
U ovom diplomskom radu opisano je elasto-plastično deformiranje mikrostrukture sinteriranog čelika Astaloy Mo+0,2C. Kako bi postupak dobivanja potrebnih modela za opisivanje deformiranja mikrostrukture bio što kraći definirali smo minimalnu potrebnu veličinu modela. Primijenjena je direktna numerička simulacija na reprezentativnim volumenskim elementima, no prije provedbe samih analiza dana je teorijska pozadina potrebna za opisivanje problematike deformiranja sinteriranog čelika u elasto-plastičnom području. Elasto-plastično područje deformiranja opisano je primjenom Ramberg-Osgood-ovog pristupa uz pomoć metode konačnih elemenata koristeći programski paket Abaqus. Provedeno je istraživanje utjecaja veličine RVE modela na mehaničko ponašanje sinteriranog čelika Astaloy Mo+0,2C. Provedene numeričke analize verificirane su usporedbom s rezultatima dobivenima pomoću numeričkih simulacija temeljenih na metodi faznih polja.
U konačnici, ovim diplomski radom prikazana je metodologija za kalibraciju materijalnih parametara elastičnosti i plastičnosti za numeričke materijalne modele za provedbu numeričkih simulacija na makro- i mikro-razini koja se temelji na usporedbi numeričkih rezultata s eksperimentalnim rezultatima dobivenima provedbom vlačnog testa. Pokazano je kako mikrostruktura materijala utječe na rezultate numeričkih analiza te su predložene neke smjernice za poboljšavanje primijenjene metodologije.

Abstract (english)

The emergence of a new but extremely important branch of modern industry, the powder metallurgy industry in today's world is increasingly emerging as a necessity due to its speed of manufacturing individual components. Sintered metal products obtained by powder metallurgy have been successfully replacing those obtained by more classical methods such as casting or forging steel for many years. This is primarily due to a significant reduction in production costs, manufacturing accuracy, surface smoothness, etc.
This thesis describes the elasto-plastic deformation of the microstructure of sintered steel Astaloy Mo + 0.2C. In order to make the process of obtaining the necessary models for describing the deformation of the microstructure as short as possible, we defined the minimum required model size. Direct numerical simulation on representative volume elements was applied, but before the analyzes were performed, the theoretical background was given to describe the problem of deformation of sintered steel in the elasto-plastic region. The elasto-plastic deformation region was described using the Ramberg-Osgood approach using the finite element method using the Abaqus software package. A study of the influence of the size of the RVE model on the mechanical behavior of sintered steel Astaloy Mo + 0.2C was performed. The performed numerical analyzes were verified by comparison with the results obtained using numerical simulations based on the phase field method.
Finally, this thesis presents a methodology for calibration of material parameters of elasticity and plasticity for numerical material models for the implementation of numerical simulations at the macro- and micro-level based on the comparison of numerical results with experimental results obtained by tensile test. The microstructure of the material has been shown to influence the results of numerical analyzes and some guidelines for improving the applied methodology have been proposed.

• Keywords: sinterirani materijal; sinterirani čelik; Astaloy Mo+0; 2C; metalografija; metoda konačnih elemenata; direktna numerička simulacija; reprezentativni volumenski element; mikrostruktura; poroznost; elasto-plastično ponašanje materijala; Ramberg-Osgood-ov pristup
• Keywords (english): sintered material; sintered steel; Astaloy Mo + 0.2C; metallography; finite element method; direct numerical simulation; representative volume element; microstructure; porosity; elasto-plastic behavior of the material; Ramberg-Osgood approach
• Language: croatian
• URN:NBN: urn:nbn:hr:235:065523
• 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: 2020-11-26 09:37:05