Title (srp)

Karakterizacija kompozita sa osnovom od Al18Si legure i njihova primena kod triboloških elemenata sa pravolinijskim naizmeničnim kretanjem

Author

Miladinović, Slavica, 1991-

Contributor

Stojanović, Blaža, 1974-
Vencl, Aleksandar, 1974-
Glišović, Jasna, 1969-
Banić, Milan, 1978-
Džunić, Dragan, 1981-
Gajević, Sandra, 1989-

Description (eng)

The development of the automotive industry increases the requirements for higher vehiclereliability and weight reduction. Weight reduction of the vehicle can be achieved by reductionof the weight of the engine. The important part of the engine is a piston, which works inaggressive conditions. Hypereutectic Al-Si alloys are increasingly used in the production ofpistons due to their good properties such as good thermal and electrical conductivity, highstrength-to-weight ratio and good corrosion resistance.In this dissertation, tribological tests were performed on two series of composite materials (Аand B) with micro and nano reinforcements in hypereutectic Al18Si alloy base. The materialsof A series included a total of 6 materials, one of which is a Al18Si alloy base, while the othermaterials are composites obtained by addition of 10 wt.% SiC (30 µm) and 1 wt.% or 3 wt.%Gr (17 µm or 200–800 µm). Within the B series of materials, there were a total of 8 materials,i.e. the alloy base and 7 composites. The composites of this series were obtained by addition of0.5 wt.% Al2O3 (20–30 nm) and/or 3 wt.% Al2O3 (36 µm) and/or 3 wt.% SiC (40 µm) and/or3 wt.% Gr (250–500 µm). Before the tribological tests, the microstructural characterization wasperformed, as well as the hardness and density measurements of the mentioned materials.Tribological tests were performed under lubricated sliding conditions at a sliding speed of0.5 m/s, sliding distance of 1000 m and a normal load of 100 N, 200 N and 300 N.Considering that the series of materials in A showed better characteristics, tribological testswere conducted for this material series on apparatus with linear reciprocating motion and thesame test conditions.After the tribological analysis, Taguchi-grey and artificial neural networks (ANN) optimizationmethods were applied to predict the behavior of wear rate and coefficient of friction for bothseries of materials. The optimal combination of parameters was obtained and the percentageinfluence of the observed factors on the wear rate and coefficient of friction was obtained byanalysis of variance (ANOVA).At the end of the research, a numerical finite element method (FEM) analysis of the piston wasperformed at a pressure of 7.5 MPa and temperatures from 300°C to 400°C. During the FEManalysis, the highest stresses were on the inside of the piston head and at the bearing of thepiston pins, and it was proven that the tested composites can be used for the production ofpistons.

Description (srp)

Razvoj automobilske industrije povećava zahteve za smanjenjem mase i povećanjempouzdanosti vozila. Smanjenje mase vozila moguće je postići smanjenjem mase motoračiji je bitan deo klip, koji radi u otežanim uslovima. Sve veću primenu priproizvodnji klipova imaju nadeutektičke Al-Si legure zbog svojih dobrih osobina kaošto su dobra termička i električna provodljivost, visok odnos čvrstoće i mase i dobraotpornost na koroziju.U ovoj disertaciji izvršena su tribološka ispitivanja dve serije kompozitnihmaterijala (A i B) sa mikro i nano ojačavačima i osnovom od nadeutektičke Al18Silegure. Serija materijala A u svom sastavu je imala ukupno 6 materijala od kojih je jedanosnovna legura dok su ostali materijali kompoziti dobijeni dodavanjem 10 mas.% SiC(30 µm) i 0,5 mas.% Al2O3 (20–30 nm) i 1 mas.% ili 3 mas.% Gr (17 µm ili 200–800 µm).U okviru serije materijala B bilo je ukupno 8 materijala, odnosno osnova i 7 kompozita.Kompoziti ove serije materijala dobijeni su dodavanjem 0,5 mas.% Al2O3 (20–30 nm)i/ili 3 mas.% Al2O3 (36 µm) i/ili 3 mas.% SiC (40 µm) i/ili 3 mas.% Gr (250–500 µm).Pre triboloških ispitivanja izvršena je mikrostrukturna karakterizacija, kao imerenje tvrdoće i gustine navedenih materijala. Tribološka ispitivanja izvršena suu uslovima sa podmazivanjem pri brzini klizanja od 0,5 m/s, pređenom putu od 1000 m inormalnim opterećenjima od 100 N, 200 N i 300 N.S obzirom na to da je serija materijala A pokazala bolje karakteristike, za ovu serijumaterijala sprovedena su i tribološka ispitivanja na uređaju sa pravolinijskimnaizmeničnim kretanjem za iste uslove ispitivanja.Nakon izvršene tribološke analize primenjene su optimizacione metode Taguči-grej(Taguchi-grey) i veštačke neuronske mreže (Artificial neural networks – ANN) zapredviđanje intenziteta habanja i koeficijenta trenja za obe serije materijala.Dobijena je optimalna kombinacija parametara i analizom varijanse (Analysis ofVariance – ANOVA) dobijen je procentualni uticaj posmatranih faktora na intenzitethabanja i koeficijent trenja.Na kraju istraživanja izvršena je numerička analiza klipa metodom konačnihelemenata (MKE) pri pritisku od 7,5 MRa i temperaturama od 300°S do 400°S. Pri MKEanalizi najviši naponi bili su sa unutrašnje strane čela klipa i kod ležištaosovinica i dokazano je da se ispitivani kompoziti mogu primeniti za proizvodnjuklipova.

Description (srp)

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Object languages

Serbian

Date

2024

Rights

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