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SEM/EDS investigation of one-step flame sprayed and fused Ni-based self-fluxing alloy coatings on steel substrates
No full textThis study presents the results of light optical and scanning electron microscopy as well as energy dispersive spectroscopy investigation of the Ni-based self-fluxing alloys (NiCrBSi, NiCrWBSi and NiCrBSi + WC) deposited on steel substrates (heat treated carbon steel C45, heat treated low-alloyed steel 42CrMo4 and austenitic stainless steel X6CrNiMo18-10-2) by one-step flame spraying and fusing process. The microstructure of coatings and coating/substrate interface but also the effects of deposition technology on the heat-treated steel substrates which have frequently been used in practice were investigated. The influence of the sample size on the microstructure was also discussed. A proof is given of the change in the structure of coating, coating/substrate interface and substrate due to high fusing temperature, depending on type of steel substrate (and relating thermal properties), coating thickness but also on dimensions of the sample
Oxidation behavior of advanced multiphase structural steels at high temperatures
Get PDFU ovom radu ispitano je oksidacijsko ponašanje višefaznih konstrukcijskih čelika pri T = 650 oC, kao i korozijska otpornost u 3,5% otopini NaCl termički tretiranih uzoraka. Elektrokemijska mjerenja su pokazala da termički tretirani uzorci poprimaju pozitivniji korozijski potencijal i pokazuju manju brzinu korozije od termički netretiranih uzoraka. Analizom EIS – spektara ustanovljeno je da termički tretirani uzorci pokazuju veći otpor prijenosu naboja, što znači da nastali oksidni sloj ima zaštitnu ulogu u korozijskom procesu i dovodi do smanjenja brzine korozije. Metalografska ispitivanja su pokazala da su ispitani konstrukcijski čelici izrazito sitnozrnate mikrostrukture koja se sastoji od ferita, bainita i zaostalog austenita. Manji sadržaj zaostalog austenita po granicama zrna kod uzoraka J i K doveo je do bolje korozijske otpornosti u 3,5% otopini NaCl, budući da su mogućnosti za formiranje korozijskih članaka bitno smanjene.In this paper oxidation behavior of advanced multiphase structural steels at T = 650 oC was studied, so as corrosion resistance in 3,5% NaCl solution of heat treated samples. Electrochemical measurements have shown that heat treated samples adopt more positive
corrosion potentials and show lower corrosion rate than not heat treated samples. By analisys of EIS spectrum was found that heat reated samples have higher charge transfer resistance which means that formed oxide layers have protective role in corrosion process leading to decrease in corrosion rate. Metallographic examinations have shown that samples have very fine grain microstructure consisted of ferrite, bainite and residual austenite. Residual austenite situated at grain boundaries in samples J and K lead to better corrosion resistance in 3,5% NaCl solution because the probabilities of formation of local galvanic cells were decreased
The effect of heat treatment on microstructure and properties of CuAlNi shape memory alloy
Get PDFDetaljnim proučavanjem literature nisu u potpunosti utvrđeni mehanizmi utjecaja
toplinske obrade (kaljenje 850 – 920 °C i popuštanje 150 – 300 °C) na svojstva
(mikrostruktura, tvrdoća, istezljivost, obradivost) kontinuirano lijevane CuAlNi slitine, stoga
postoji opravdani razlog za provođenje ovog istraživanja.
U radu je detaljno analizirana promjena mikrostrukture i mehaničkih svojstava
CuAlNi slitine s prisjetljivošću oblika (kontinuirano lijevana šipka ϕ 8 mm) toplinskom
obradom pri različitim temperaturama. Toplinska obrada je obuhvaćala postupak kaljenja na
temperaturama 850 °C, 885 °C i 920 °C u trajanju od 60 minuta te naglog hlađenja u vodi
sobne temperature. Nakon postupka kaljenja provedeno je popuštanje na 150 °C, 200 °C, 250
°C i 300 °C u trajanju od 60 minuta te hlađenje u vodi.
Ispitivanje mikrostrukture je provedeno optičkim, pretražnim i transmisijskim
elektronskim mikroskopom te rendgenskom faznom analizom. Utvrđeno je da je martenzitna
mikrostruktura prisutna u svim uzorcima (lijevano, kaljeno i popušteno stanje). Rendgenskom
faznom analizom utvrđeno je postojanje dvije vrste martenzita u mikrostrukturi nakon
kaljenja i popuštanja (β1' i γ1'), što znači da temperatura i postupak toplinske obrade značajno
utječe na razvoj mikrostrukturnih konstituenata slitine, koji imaju važan utjecaj na
funkcionalna svojstva slitine. Analizom prijelomnih površina utvrđeno je postojanje
transkristalnog prijeloma u uzorcima nakon lijevanja, kaljenja i popuštanja na 150 °C.
Međutim, gotovo potpuni interkristalni tip prijeloma zamijećen je u uzorcima popuštenim na
300 °C.
Ispitivanjem mehaničkih svojstava utvrđeno je da najveći iznos vlačne čvrstoće ima
uzorak kaljen 850 °C/60'/H2O (498,6 MPa), a najnižu vrijednost vlačne čvrstoće nakon
kaljenja ima uzorak kaljen 885 °C/60'/H2O (367,5 MPa). Uočeno je da granica razvlačenja s
porastom temperature kaljenja opada. Vrijednost istezanja je niska za sve ispitane uzorke (< 5
%). Najveća vrijednost istezanja izmjerena je za uzorak slitine nakon lijevanja (4,75 %).
Postupak kaljenja nepovoljno utječe na istezanje slitine, gdje je uočeno smanjenje vrijednosti
istezanja (3,55 %, 2,72 % i 2,95 %) u odnosu na lijevano stanje. Istezanje nakon popuštanja
opada s porastom temperature popuštanja, s iznimkom uzorka kaljenog 920 °C/60’/H2O i
popuštenog 200 °C/60’/H2O.
S obzirom na uvjete primjene CuAlNi slitine, provedena su detaljna elektrokemijska
ispitivanja u 0,9% NaCl, pri različitim pH vrijednostima te različitoj koncentraciji kloridnih
iona, kako bi se pratio utjecaj promjena u okolini (otopini) na ponašanje CuAlNi slitine.
Zamijećeno je da dolazi do pada gustoće korozijske struje na uzorcima kaljenim na 850 °C i
920 °C u odnosu na lijevano stanje. Iznimka je uzorak kaljen na 885 °C kod kojeg dolazi do
porasta što upućuje na intenzivnije otapanje slitine. Također, negativan utjecaj uočen je
smanjenjem pH i povećanjem koncentarcije kloridnih iona na korozijsko ponašanje CuAlNi
slitine s prisjetljivošću oblika. Brzina korozije s porastom temperature kaljenja opada,
iznimka je uzorak kaljen na 885 °C. Sa smanjenjem pH otopine uočen je porast brzine
korozije, a porastom koncentracije kloridnih iona zamijećen je porast brzne korozije osobito u
0,9 % i 1,5 % NaCl.Through a detailed study of literature it is noticed that the mechanisms of influence of
heat treatment (solution annealing at 850 – 920 °C and tempering at 150 – 300 °C) on
properties (microstructure, hardness, ductility, formability) in continuously cast CuAlNi alloy
are not fully determined, and therefore exists a justified reason for the following research.
In this work, a detailed analysis of changes in microstructure and mechanical
properties of the CuAlNi shape memory alloy (continuously cast bar of 8 mm in diameter)
with heat treatment at different temperatures will be carried out. The heat treatment processes
included solution annealing at temperatures of 850 °C, 885 °C and 920 °C for 60 minutes and
rapidly cooling in room temperature water. After the annealing process, tempering is
performed at 150 °C, 200 °C, 250 °C and 300 °C for 60 minutes, followed by cooling in
water.
Microstructural analysis was performed by optical, scanning and transmission electron
microscopy, and X-ray diffraction analysis. It was found that the as-cast sample and samples
after quenching and tempering had fully martensitic microstructure. X-ray diffraction analysis
showed the existence of two types of martensite in the microstructure after solution annealing
and tempering (β1' and γ1'), which means that the temperature of the heat treatment has
significant influence on the development of alloys’ microstructural constituents, which have
an important influence on the functional properties of the alloy. The analysis of the fracture
surfaces, the existence of transgranular type of fracture in the samples after casting, quenching
and tempering at 150 ° C was noticed. However, almost complete intergranular type of
fracture can be observed in the samples tempered at 300 ° C.
During the study of the mechanical properties it was found that the largest value of
tensile strength has the sample solution annealed at 850 °C/60'/H2O (498.6 MPa), and the
lowest tensile strength has the sample solution annealed at 885 °C/60'/H2O (367.5 MPa). It
was observed that the yield strength with the increasing of tempering temperature decreases.
Elongation has very low values for all tested samples (below 5%). The maximum value of
elongation was measured for the sample of the alloy after casting (4.75%). Solution annealing
process has no favourable influence on alloys’ elongation, where there is visible decrease of
the elongation (3.55%, 2.72% and 2.95%) compared to the value obtained in as-cast
condition. Elongation after tempering decreases as the tempering temperature decreases, with
the exception of the sample solution annealed at 920 °C/60'/H2O and tempered 200
°C/60'/H2O.
Considering to a CuAlNi alloys application conditions a detailed electrochemical tests
in 0.9% NaCl were performed. Electrochemical tests were performed at different solution pH
and different concentrations of chloride ions, in order to observe the influence of
environmental changes (solution) on the behaviour of the CuAlNi alloy. It was noticed that
corrosion current density decreases on the samples solution annealed at 850 °C and 920 °C
compared to the as-cast state sample. The exception is the sample annealed at 885 °C in
which there is an increase of corrosion current density indicating a more intensive dissolution
of the alloy. Also, the negative impact on the corrosion behaviour of CuAlNi shape memory
alloy was observed by decreasing the pH of the solution and increasing the concentration of
chloride ions in the solution. Corrosion rate decreases with the increase of solution annealing
temperature; the exception is sample solution annealed at 885 °C. Corrosion rate increas es
with decreasing pH of the solution and increasing the concentration of chloride ions,
especially in 0.9 and 1.5% NaCl solution
Annual computation of CO2 emission from electric arc furnace steel making process
Get PDFSve djelatnosti koje u proizvodnim procesima emitiraju stakleničke plinove (definirano Uredbom o načinu trgovanja emisijskim jedinicama stakleničkih plinova), kao što su CO2, N2O, PFC, itd. moraju podnijeti "Izvješće o godišnjim emisijama iz postrojenja". U izvješću izvori emisija i materijali trebaju biti točno identificirani te izračunata količina ispuštenog CO2. Budući da industrija proizvodnje čelika zahtijeva visoku temperaturu, koja se dobiva pomoću raznih goriva (prvenstveno fosilnih goriva i električne energije), oni imaju obvezu podnošenja "Izvješća o godišnjim emisijama iz postrojenja."
U ovom radu opisan je elektropećni postupak za proizvodnju čelika u čeličani ABS SISAK d.o.o. te je izračunata godišnja emisija CO2 za 2015. godinu. Za potrebe izračuna emisije CO2 dan je prikaz svih sirovina koje sadrže ugljik, njihov sadržaj ugljika i iznos utrošenih sirovina. Izračunata je emisija od 18.382 t CO2 za 2015. godinu. Da bi se osigurala vjerodostojnost podataka, izvješće obavezno prolazi postupak verifikacije od strane ovlaštenog verifikatora koji isto provjerava i odobrava (sukladno Uredbi EU br. 600/2012).All industries which have in their manufacturing process greenhouse gas emissions (defined by the Regulation on greenhouse gas emission units trading, Official gazette 69/12), such as CO2, N2O, PFC, etc. must submit a "Report on annual emissions from plant". In report emission sources and materials should be exactly identified and the amount of emitted CO2 calculated. Since the industries of steel production requires a high temperature, which is obtained from a variety of fuels (primarily fossil fuel or electricity), they have obligation to submit "Report on the annual emissions from the plant."
In this paper, the electric arc furnace process for producing the steel in plant ABS Ltd. Sisak has been described and the annual CO2 emission for Year 2015 has been calculated. For calculation of CO2 emission, all raw materials containing carbon, their carbon content and amount of spent raw materials were shown. Calculated CO2 emission for year 2015 was 18382 t CO2. To ensure the credibility of the data, the report has to undergo verification procedure by an authorized verifier for verification and approval (according to Regulation EU no. 600/2012)
Techniques for particle purification from waste gases
Get PDFRazvoj čovječanstva doveo je do intenzivnog tehnološkog razvoja, povećanja produktivnosti
i proizvodnje novih vrsta proizvoda i usluga, što ima za posljedicu povećanje onečišćenja
zraka, vode i tla. Stoga je tema očuvanja okoliša, kontrole onečišćenja te pokušaji smanjenja
koncentracije onečišćujućih tvari ključna u posljednjih desetak godina. U tom smislu
donesena je zakonska regulativa te preporuke o graničnim vrijednostima koncentracija
onečišćujućih tvari u okolišu, kao i preporuke za implementaciju najbolje raspoloživih
tehnika u industrijskim procesima. U ovom radu dan je prikaz osnovnih izvora onečišćenja
zraka te tehnike pročišćavanja krutih čestica iz otpadnih plinova tehnoloških procesa.Intensive technological development increased productivity of new products and services,
what results in increased air, water and soil pollution. Therefore, the environmental theme,
pollution control and attempts to reduce concentrations of pollutants have been crucial in the
last decade. Consenquently, legislation as well as recommendations on the limit values of
pollutant concentrations in air and best available techniques have been harmonized. In this
paper, basic sources of air pollution as well as techniques for particle purfication from waste
gases were presented
Validation of inductively coupled plasma spectrometric method and atomic absorption spectrometry for determination of nickle
No full textU ovom radu je provedena validacija dvije spektrometrijske metode za odreĎivanje niklaoptičke emisijske spektrometrije s induktivno spregnutom plazmom (ICP-AES) i atomske
apsorpcijske spektrometrije (AAS). Tijekom validacijskog postupka odreĎivana je: točnost,
preciznost, linearnost, radno područje, specifičnost, selektivnost, granica detekcije, granica
kvantifikacije i reproducibilnost. Dobiveni podaci ukazuju na to da su obje ispitivane metode
točne, precizne, specifične, selektivne i reproducibilne. Ispitivanja su pokazala da metoda
atomske apsorpcijske spektrometrije nema zadovoljavajuću linearnost. Obje ispitivane metode
mogu se koristiti za odreĎivanje niskih koncentracija nikla budući da im je granica detekcije
0,7513 µg/L odnosno 0,7947 µg/L.In this graduation thesis, two spectrometric methods for the determination of nickel -inductively coupled plasma optical emission spectrometry (ICP - AES) and atomic absorption
spectrometry (AAS) were validated. During the validation process, the accuracy, precision,
linearity, working area, specificity, selectivity, detection limit, quantification limit and
reproducibility were determined. The obtained data indicate that both methods were accurate,
precise, specific, selective and reproducible. Tests have shown that the atomic absorption
spectrometry method does not have satisfactory linearity. Both test methods can be used to
determine low nickel concentrations as their detection limits are 0.7513 μg/L and 0.7947
μg/L
Usporedba sastava i stabilnosti troske kod proizvodnje čelika u elektrolučnoj peći
Get PDFProizvodnja čelika u čeličanama također rezultira i nastajanjem većih količina troske kao proizvodnog ostatka. Tako dobivena troska može se primjenjivati u različitim granama industrije, ovisno o njenim svojstvima i sastavu, koji se dodatnim postupcima prilagođavaju specifičnim zahtjevima primjene. Toplinska stabilnost troske ovisi o sastavu i morfologiji, što je posljedica načina proizvodnje čelika i brzine hlađenja troske. U ovom radu je ispitana toplinska stabilnost uzorka troske dobivene u procesu proizvodnje niskougljičnog čelika u elektrolučnoj peći u kompaniji ABS Sisak d.o.o. Ispitivanja su provedena simultanom tehnikom toplinske analize, diferencijalnom toplinskom analizom i termogravimetrijskom analizom te su određeni temperaturni intervali gubitka mase.Steel production steelworks results also in large amounts of steel slag as a byproduct. The resulting slag can be applied in different branches of the industry, depending on its properties and composition, which are tailored to the specific application requirements by additional procedures. Thermal stability of slag depends on its composition and morphology, which is a consequence of steel production process and cooling speed of slag. Therefore, the heat stability of the slag sample, obtained in the process of steel production in the electric-arc furnace in ABS Sisak d.o.o., was investigated in this work. Investigations were performed bysimultaneous thermal analysis, differential thermal analysis and thermogravimetry. Temperature intervals of loss of mass of slag sample were determined
Microscopy analysis of Cu-Al-Mn alloy microalloyed with titanium
Get PDFU ovom radu provedena je mikroskopska analiza (optička mikroskopija, pretražna elektronska mikroskopija i energetsko disperzijska spektrometrija) i ispitivanje tvrdoće Cu-9Al-7Mn legure mikrolegirane s titanom (0,4 mas.%). Analiza je provedena za leguru u lijevanom stanju (ingot) i nakon toplinske obrade (900 oC/30 min/ H2O). Legura je pripremljena iz čistih elemenata istaljenih u elektrolučnoj vakumskoj peći pod zaštitnom atmosferom argona. Nakon lijevanja u kalup provedena je toplinska obrada (kaljenje) i metalografska priprema. Mikrostrukturna karakterizacija provedena je optičkom mikroskopijom i pretražnom elektronskom mikroskopijom (SEM) s energetsko disperzijskom spektrometrijom (EDS). Temperatura faznih prijelaza ispitivana je diferencijalno pretražnom kalorimetrijom (DSC). Tvrdoća uzoraka u lijevnom i kaljenom stanju mjerena je Vickersovom metodom. U lijevanom uzorku nije utvrđena prisutnost martenzitne faze, dok je nakon toplinske obrade utvrđena prisutnost martenzitne faze. Temperature faznih prijelaza nisu vidljive na krivulji prilikom ispitivanja DSC analizom od sobne temperature do 300 oC. Nakon toplinske obrade došlo je do značajnog povećanja tvrdoće legure.In this paper microscopy analysis (optical microscopy, scanning electron microscpy and energy dispersion spectrometry) and hardness testing was carried out of Cu-9Al-7Mn alloy microalloyed with titanium (0.4 wt.%). Analysis was performed in as-cast state and after heat treatment (900 oC/30 min/ H2O). Alloy was prepared from pure metals in vacum electroarc furnace under the protective argon atmosphere. The heat treatment and metalographic preparation was performed after casting. Optical and scanning electron microscopy (SEM) with energy dispesion spetrometry (EDS) was used for microstructural analysis. Diferential scanning calorimetry was used for measuring temperatures of phase transformations. For hardness of samples in as-cast and as-quenched state Vickers method was used. In as-casted sample martensite phase was not detected, while after heat treatment martensite phase was detected. Phase transformation temperatures were not visible od the DSC curve measured from room temperature to 300 oC. After heat treatment significant increase in hardness of analyzed alloy was observed
Investigation of AlSi7Mg alloy properties
Get PDFAluminijske legure su okarakterizirane izvrsnim mehaničkim, fizikalno- kemijskim i
tehnološkim svojstvima, čime su veliku primjenu pronašle u automobilskoj industriji. U
automobile se trenutno ugrađuje oko 140 kg aluminijskih legura (glava i blok motora, nosači
ležajeva, mjenjača, naplataka i slično). Bez obzira na sve kompliciraniju geometriju dij elova i
sklopova, ta je brojka stalno u porastu, zahvaljujući inovativnim tehnologijama lijevanja. Sa
sve većim udjelom dijelova od aluminijskih legura (i ostalih lakih metala i materijala) ,
performanse, sigurnost i ekološka prihvatljivost automobila raste. Geometrija odljevka utječe
na odabir odgovarajuće legure, naknadnu obradu i zahtijevana/dobivena svojstva poput
otpornosti na koroziju, otpornost na visoke temperature, čvrstoću, tvrdoću, itd., pa se uz glavni
legirajući element Si, Al - Si legurama dodaju se i sekundarni legirajući elementi ili elementi u
tragovima poput primjerice Mg. U okviru ovog rada dokazalo se da različite brzine hlađenja i
naknadna toplinska obrada imaju značajan utjecaj na postignuta svojstva odljevaka. Razvoj
mikrostrukture i njezine značajke u različitim uvjetima skrućivanja daju uvid u vođenje procesa ,
i izrazito utječu na mehanička svojstva. Mikrostrukturna analiza ukazala je na prisu t nost
sl jedećih mikrostrukturnih konstituen ata: primarni aluminij (- Al), eutektik (- Al+β- Si),
intermetalne željezne faze Al 5FeSi i Al 8FeMg 3Si 6 te sekundarnu eutektičku fazu - Al+Mg2Si. U toplinski obrađenim uzorcima uočena je veća sklonost ka izdvajanju kompleksne
intermetalne Al 8FeMg 3Si 6 faze koja, uz precipitaciju Mg , povoljno utječe na poboljšanje
mehaničkih svojstava. Sferoidizacija primarnog aluminija, bez ob zira na pogrubljivanje, ima
pozitivan učinak na mehanička svojstva. Mikrostrukturne značajke pokazale su se kao
preliminarni pokazatelj provedenih postupaka, na osnovu kojeg je moguće predvidjeti
postignuta svojstva konačnog odljevka.Aluminium alloys are characterized by excellent mechanical, physically - chemical and
technological properties, which represent the foundation for wide application in automotive
industry . Todays’ vehicles contain around 140 kg of aluminium alloys (engine head and block, bearing support, gear box, wheels etc.). In despite of more and more compl ex geometry of parts and assembl ies, th e use is in constant growth , due to innovative casting technologies. With increasing ratio of aluminium alloys parts (and other light metals and materials), performances, safety and environmental sustainability of vehicle also increase. Casting geometry influences the selection of corresponding alloy, machining and demanded/achieved properties such as corrosion resistance; high temperature resistance, strength, hardness etc., Therefore, beside addition of main alloying element Si, also secondary alloying or trace elements such as Mg are added. Within this paper it was proven that different cooling rates and heat treatment have significant influence on achieved casting properties. The development of microstructure and its features related to different solidification conditions have indicate the process management, and particularly influence on mechanical properties. Microstructural analysis has indicated the presence of following microstructural consti tuents: primary aluminium (- Al), eutectic (-Al+β- Si), intermetallic iron phase Al 5FeSi i Al 8FeMg 3Si 6 and secondary eutectic phase -Al+Mg2Si. In heat treated samples, the higher tendency toward forming complex intermetallic Al 8FeMg 3Si 6 phase was observed, which along with Mg precipitation, affects posi tively on mechanical properties. Sph eroidi z ing of primary aluminium and its coarsening , have a positive effect on mechanical properties. Microstructural features have been imposed as a preliminary indicator of processes, and represent the base for predicti on of achieved casting properties
Strength analysis of circular manhole cover
Get PDFU radu je analiziran problem nosivosti kruţnog kanalskog poklopca (šahte) za odabranu vrstu
materijala. Korištenjem programskog paketa Autodesk Simulation Mechanical u edukacijskoj
verziji provedena je trodimenzionalna linearna statiĉka analiza savijanja lijevanog kruţnog
kanalskog poklopca primjenom metode konaĉnih elemenata. Analiza je provedena u više
razliĉitih izvedbi konstrukcije poklopca. Pošto je kruţni poklopac s cirkularnim i radijalnim
rebrima cirkularno simetriĉan, u analizi je korištena geometrija samo jednog dijela kruţnog
poklopca. Taj dio poklopca prvo je diskretiziran konaĉnim elementima te su na njega
postavljeni uvjeti zadanog opterećenja, oslanjanja te rubni uvjeti cirkularne simetrije. Pošto su
analitiĉka rješenja ograniĉena na jednostavnije geometrijske probleme kao što je savijanje
tanke kruţne ploĉe time je prvo provedena numeriĉka simulacija za tanku kruţnu ploĉu.
Rezultati progiba, radijalnog te cirkularnog naprezanja dobiveni numeriĉkom simulacijom
usporeĊeni su s analitiĉkim rješenjem. U numeriĉkoj simulaciji ekvivalentna naprezanja
praćena su energijskom teorijom ĉvrstoće (HMH - von Mises). Nakon verifikacije numeriĉkih
rezultata, savijanja tanke kruţne ploĉe, na ploĉu su potom s donje strane najprije dodana
cirkularna rebra i provedena je simulacija savijanja u ovakvoj izvedbi ploĉe. Uoĉavanjem
egzistiranja popriliĉno velikih ekvivalentnih naprezanja na jednom dijelu ploĉe provedena je
sljedeća numeriĉka simulacija s dodavanjem radijalnih rebara. Analizirajući rezultate
zakljuĉuje se da dodavanjem cirkularnih i radijalnih rebara po donjem dijelu ploĉe
maksimalna ekvivalentna naprezanja s kruţnog poklopca prelaze na postavljena rebra.
Analizom rezultata zadnje simulacije napravljen je odabir materijala (nodularni ili sivi lijev) s
obzirom na zadanu nosivost.In this paper the loading problem of circular manhole cover for chosen type of material is analyzed. Using the software package Autodesk Simulation Mechanical in educational
version three-dimensional linear static analysis of bending casted circular manhole cover
using the finite element method was conducted. The analysis in several versions of the
different cover construction was conducted. As the circular cover with circular and radial ribs
is circularly symmetrical, in the analysis geometry of only one part of cover has been used.
Firstly, that part of the cover using the finite elements was discretized and then the boundary
conditions of specified load, reliance and boundary conditions of circular symmetry had set.
As analytical solutions are limited to simple geometric problems such as bending of thin
circular plate, in a first place a numerical simulation of a thin circular plate was carried out.
Results of deflection, radial and circular stresses obtained by numerical simulation with
analytical solution are compared. In numerical simulation equivalent stresses with energy
theory of strength (HMH - von Mises) were monitored. After verification of numerical results
of bending thin circular plate, on the bottom of plate the circular ribs were added and
numerical simulation of bending this design of plate was carried out. With notification of
existence of quite a large equivalent stress in one part of plate, another numerical simulation
with addition of radial ribs was carried out. Analyzing the results it was concluded that with
addition of circular and radial ribs at the bottom of cover maximum equivalent stress with the
circular cover passes to the ribs. By analyzing the results of the last simulation material
(ductile or grey iron) selection with respect to a given load was made