Određivanje konstitutivnog ponašanja mikrokonstituenata sinteriranog čelika

master's thesis

• Title (english): Determination of constitutive behaviour of sintered steel microconstituents
• Author: Danilo Dobrić
• Mentor: Tomislav Lesičar (mentor)
• Mentor: Ante Jurčević (komentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2024-12-09, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Sinterirani čelik popularan je materijal sa širokim područjem primjene u industriji. Mikrostruktura sinteriranog čelika je porozna, što za posljedicu ima opasnost od koncentracije naprezanja na mikrorazini i nepredviđenog pucanja. Višerazinske metode prikladan su alat za analizu problema kod kojih je bitno modelirati materijal na mikro- i makrorazini. Koristeći jednu vrstu višerazinske metode, to jest računalnu homogenizaciju prvog reda, proveden je niz proračuna na reprezentativnim elementima mikrostrukture sinteriranog čelika Astaloy Mo+0,2C. Proračuni su provedeni uzimajući u obzir sve moguće kombinacije materijalnih parametara mikrokonstituenata (ferita i bainita) dobivenih instrumentiranom indentacijom u doktorskoj disertaciji dr. sc. Zorana Tomića, gdje se numerički proračun nije podudarao s makrorazinskim eksperimentom. Podaci dobiveni numeričkom simulacijom u ovom radu uspoređivani su s rezultatima jednoosnog vlačnog testa u spomenutoj disertaciji. Ponovno veliko odstupanje numeričke simulacije na mikrorazini od eksperimenta na makrorazini ukazuje na nepreciznost metode determinacije mehaničkih svojstava mikrokonsitutenata ili upitnu valjanost pretpostavki i pojednostavljenja uključenih u računalni model.

Abstract (english)

Sintered steel is a popular material with a wide range of industrial applications. The porosity of sintered steel microstructure makes it susceptible to micro-level stress concentration and unanticipated cracking. Multiscale methods are an useful modeling tool in situations when it is important to take both the microscale and the macroscale mechanical behaviour into account. Using one type of multiscale methods, i.e. first-order computational homogenization, multiple analyses were carried out using representative microstructural elements of Astaloy Mo+0.2C sintered steel. The simulations were carried out by evaluating all possible combinations of material parameters of microconstituents (ferrite and bainite) obtained by instrumented indentation in the doctoral dissertation of Zoran Tomić, PhD, in which the numerical analysis did not match the macroscale experiment. The data obtained by numerical simulation in this paper were compared with results of the uniaxial tensile test in the aforementioned dissertation. A recurrent large deviation of the numerical analyses at the micro-level from the experiment at the macro-level indicates either the invalidity of the method for determination of microconstituents' mechanical properties or the questionable validity of the assumptions and simplifications constituting the computational model.

• Keywords: sinterirani čelik; mikrostruktura; računalna homogenizacija; reprezentativni volumenski element
• Keywords (english): Key words: sintered steel; microstructure; computational homogenization; representative volume element
• Language: croatian
• URN:NBN: urn:nbn:hr:235:404393
• Study programme: Title: Mechanical Engineering; specializations in: Design, Process and Energy Engineering, Production Engineering, Engineering Modelling and Computer Simulation, Marine Engineering, Industrial Engineering and Management, Materials Engineering, Mechanics and Robotics, Autonomous Systems, Mechatronics and Robotics; Course: Engineering Modelling and Computer Simulation; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra inženjer/inženjerka strojarstva (sveučilišni/a magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-11-29 08:02:01