Određivanje parametara loma sinteriranog čelika metodom faznog polja

master's thesis

• Title (english): Determination of the fracture parameters of sintered steel by phase field method
• Author: Jakov Rako
• Mentor: Tomislav Lesičar (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2023-01-25, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Proizvodi od sinteriranog čelika u današnjoj industriji polako postaju dio svakodnevnice. Zbog
svojih dobrih svojstava poput manje mase, dobrog prigušenja, manje potrebe za naknadnom
površinskom obradom, mogućnosti legiranja raznim elementima i raznim drugim prednostima
postali su standardni u automobilskoj i zrakoplovnoj industriji. Proizvodi od sinteriranog čelika
izrađuju se metodom metalurgije praha, koja metalni prah kompaktira u kalupe i tvori proizvode
koji nakon sinteriranja imaju svojstva jednaka ili bolja od onih koja bi imali da su izrađeni nekom
od klasičnih metoda proizvodnje.
Glavne prednosti metalurgije praha su mogućnost izrade proizvoda s izrazito velikom
dimenzijskom preciznošću koje nije potrebno naknadno obrađivati, te niži troškovi proizvodnje.
Također je bitno naglasiti da je utjecaj na okoliš kod metalurgije praha puno manji nego kod
klasičnih metoda proizvodnje, prvobitno zbog toga što je manje otpada i škarta. Zbog specifičnog
načina proizvodnje sinteriranih čelika njihovo konstitutivno ponašanje je nelinearno.
Kako je u inženjerskoj praksi degradacija materijalnih svojstava i lom materijala jedan od najvećih
problema koji uzrokuju oštećenja proizvoda potrebno je pokušati predvidjeti ili spriječiti njihovo
nastajanje. Stoga je u ovom radu primijenjena metoda faznog polja za rješavanje problema
mehanike loma, pomoću koje je modelirano oštećenje. Numeričkim simulacijama u komercijalnom
programskom paketu Abaqus određeni su parametri metode faznog polja za modeliranje
konstitutivnog ponašanja sinteriranog čelika Astaloy Mo+0,2C gustoće 6,5 g/cm3
. Numeričke
simulacije uspoređene su s rezultatima statičkih eksperimentalnih ispitivanja provedenih na
Katedri za mehaniku i čvrstoću na Fakultetu strojarstva i brodogradnje u Zagrebu.
Dobiveni parametri faznog polja 𝐺c
i 𝑙 na zadovoljavajući način opisuju lomno ponašanje
sinteriranog čelika za slučaj statičkog opterećenja. U daljnjem radu bi navedene parametre trebalo
provjeriti numeričkim simulacijama s cikličkim opterećenjem kako bi se provjerio i zamorni lom
materijala.

Abstract (english)

In today's industry sintered steel products are slowly becoming part of everyday life. Due to their
good properties such as lower mass, good damping, less need for subsequent surface treatment, the
possibility of alloying with various elements and various other advantages, they have become
standard in the automotive and aerospace industries. Sintered steel products are made using the
powder metallurgy method, which compacts the metal powder into molds and forms products that,
after sintering, have properties equal to or better than those they would have if they were made by
one of the classical production methods.
The main advantages of powder metallurgy are the possibility of manufacturing products with
extremely high dimensional precision that do not need to be post-processed, and lower production
costs. It is also important to emphasize that the impact on the environment with powder metallurgy
is much smaller than with classical production methods, primarily because there is less waste and
scrap. Due to the specific method of production of sintered steels, their constitutive behavior is
non-linear.
As in engineering practice, the degradation of material properties and material failure is one of the
biggest problems that cause product damage, it is necessary to try to predict or prevent their
occurrence. Therefore, in this work, the phase-field method was applied to solve the problem of
fracture mechanics, by means of which the damage was modeled. The parameters of the phasefield method for modeling the constitutive behavior of sintered Astaloy Mo+0.2C with a density
of 6.5 g/cm3 were determined using numerical simulations in the commercial Abaqus software
package. Numerical simulations were compared with the results of static experimental tests
conducted at the Chair of Mechanics and Strength of Materials at the Faculty of Mechanical
Engineering and Naval Architecture in Zagreb.
The obtained phase-field parameters 𝐺c and 𝑙 adequately model the fracture behavior of sintered
steel for the case of static loading. In further work, the mentioned parameters should be verified by
numerical simulations with cyclic loading in order to verify the fatigue fracture of the material.

• Keywords: sinterirani čelik; Astaloy Mo+0; 2C; metoda konačnih elemenata; teorija faznog polja; numerička analiza mehanike loma; Abaqus
• Keywords (english): sintered steel; Astaloy Mo+0.2C; finite element method; phase-field theory; numerical analysis of fracture mechanics; Abaqus
• Language: croatian
• URN:NBN: urn:nbn:hr:235:270661
• 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, Mechatronics and Robotics, Autonomous Systems; Course: Engineering Modelling and Computer Simulation; 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: 2023-01-20 12:27:27