Modeliranje koncentracije naprezanja u mikrostrukturi sinteriranog čelika

undergraduate thesis

• Title (english): Modelling of stress concentration in sintered steel microstructure
• Author: Avelin Bingula
• Mentor: Zdenko Tonković (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2022-03-03, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

Sinterirani čelici su sve češći odabir u modernim konstrukcijama i prijenosnicima snage zbog svojih svojstava i jednostavnosti izrade. Proizvodni troškovi u metalurgiji praha u masivnoj proizvodnji su niži nego kod standardnih lijevanih i kovanih čelika zbog manje mase i iskoristivosti sirovine. Kako je poznato, poroznost i nepravilnosti u mikrostrukturi izazivaju koncentracije naprezanja. Pod utjecajem istog, pojavljuju se trajna oštećenja na mikrorazini, što ima direktan utjecaj na ponašanje materijala na makrorazini. Ispitivanjem materijala na makrorazini utvrđeno je drastično smanjenje materijalnih svojstava s povećanjem poroznosti. S druge strane, prema literaturi s povećanjem poroznosti u sinteriranom materijalu raste i nepravilnost pora, odnosno, kružnost pora opada s povećanjem poroznosti. Zbog toga u radu je provedena numerička analiza metodom konačnih elemenata za pore različitih veličina te je istražen utjecaj oblika pora. Korišteni modeli dobiveni su iz metalografske analize sinteriranog čelika Astaloy Mo+0,2C za slučaj monotonog vlačnog opterećenja i elastičnog ponašanja materijala. Odabrano je 15 modela podijeljenih u 3 kategorije kompleksnosti i skalirano na 4% poroznosti. Na temelju dobivenih rezultata pokazan je utjecaj kompleksnosti i opsega pore na koncentraciju naprezanja. Dobiveni rezultati uspoređeni su s dosad objavljenim istraživanjima.

Abstract (english)

Sintered steels have an increased usage in modern designs and transmission systems because of their properties and simple manufacturing process. Manufacturing costs of powder metallurgy in mass-producing are lower than conventional manufacturing of cast and forged steels because a product is lighter and there is higher raw material usage. As is well known, porosity and irregularities in microstructure cause stress concentrations. The stress concentrations cause permanent microdamage which has a direct influence on the properties of a material on a macro scale. A significant decrease in mechanical properties is observed with the porosity increase. On the other hand, studies showed that with increasing porosity in sintered steel pore irregularities increased, moreover pore circularity decreased. Because of these properties, numerical analysis with the finite element method is conducted for different shapes and sizes of pores. Models used in research are taken from metallography images of sintered steel Astaloy Mo+0,2C for a case of tension of elastic materials. 15 models are considered and distributed in 3 categories by their shape complexity and scaled to 4% porosity. Results of the analysis showed the impact of pore complexity and pore perimeter on stress concentration. Results are compared with up-to-date studies.

• Keywords: Sinterirani čelik; Abaqus; poroznost; koncentracija naprezanja; numerička analiza; metoda konačnih elemenata
• Keywords (english): Sintered steel; Abaqus; porosity; stress concentration; numerical analysis; finite element method
• Language: croatian
• URN:NBN: urn:nbn:hr:235:300139
• 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; Course: Design; 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: 2022-02-28 15:49:48