doktorska disertacija
Blaž Šamec (Author), Iztok Potrč (Mentor), Matjaž Šraml (Co-mentor)

Abstract

V predloženi doktorski disertaciji je razvit model za določitev življenjske dobe zavornih diskov tirnih vozil. Model temelji na predpostavki, da natančno poznamo hitrostni in višinski profil proge, na kateri bodo le-ti obratovali. Posledično to omogoča napovedovanje ciklov termomehanskega obremenjevanja, ki so vhodni podatek za določitev življenjske dobe zavornih diskov. Na osnovi zahtev računskih modelov za izračun življenjske dobe po deformacijski metodi je bila v sklopu doktorske naloge opravljena podrobna analiza materialnih lastnosti nodularne litine EN-GJS-500-7. Trdnostne lastnosti litine so bile analizirane z nateznimi preskusi pri sobni temperaturi (ST), 300 °C, 350 °C in 400 °C. Malo-ciklični preskusi utrujanja so bili izvedeni pri ST, 300 °C in 400 °C, za te temperature so bili določeni malo-ciklični parametri, ki so potrebni za izračun življenjske dobe, in izrisane deformacijske krivulje zdržljivosti. Ugotovljeno je bilo, da povišana temperatura močno vpliva na življenjsko dobo analizirane nodularne litine. S pomočjo numerične analize po metodi končnih elementov so bila analizirana napetostna in deformacijska polja, ki nastanejo med zaviranjem na dejanskem zavornem disku ter določeno kritično mesto konstrukcije le-tega. Na podlagi numeričnih rezultatov je bila z deformacijsko metodo izračunana življenjska doba zavornega diska v različnih obremenitvenih primerih za nov in obrabljen disk, pri čemer so bile ugotovljene dokaj velike razlike med posameznimi hipotezami, ki upoštevajo večosno napetostno stanje. Na koncu je podana še metodologija določitve življenjske dobe zavornih diskov pri vožnji na določeni progi oziroma hitrostnem sistemu.

Keywords

zavorni diski tirnih vozil;življenjska doba zavornih diskov;termomehansko utrujanje;malo-ciklično utrujanje;parametri utrujanja;deformacijska metoda;metoda končnih elementov;

Data

Language: Slovenian
Year of publishing:
Source: [Maribor
Typology: 2.08 - Doctoral Dissertation
Organization: UM FS - Faculty of Mechanical Engineering
Publisher: B. Šamec]
UDC: 629.3.018.4-52(043.3)
COBISS: 257228032 Link will open in a new window
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Downloads: 249
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Other data

Secondary language: English
Secondary title: Service life of railway brake discs under thermomechanical loading
Secondary abstract: A model for assessment of service life of railway brake disc is presented in this doctoral thesis. The model is based on the assumption that the particular railway route where brake disc will operate is precisely known. Consequently this allows prediction of thermomechanical cycles of loading, which are the input data for determination of service life for a railway brake disc. Based on the requirements of computational models for fatigue life assessment, detailed analysis of material properties of ductile cast iron EN-GJS-500-7 was done. Strength properties of cast iron were examined by tensile tests at room temperature (RT), 300 °C, 350 °C and 400 °C, while low-cycle fatigue (LCF) tests were carried out at RT, 300 °C and 400 °C. Strain-life curves were obtained and LCF parameters were determined for these temperatures. It was found out that the fatigue life of analyzed ductile cast iron is strongly affected by the increased temperature. Stress and strain fields generated during braking on the actual brake disc were analyzed with finite element method and a critical area of brake disc design has been determined. Based on numerical results, fatigue life was calculated for new and worn disc in different braking regimes, where relatively large differences between the various hypotheses that take account of multiaxial stress state were found. In the end, methodology for determining fatigue life of brake discs while driving on a particular route is presented.
Secondary keywords: railway brake discs;serice life of railway brake discs;thermomechaninical fatigue;low cycle fatigue;fatigue parameters;strain method;finite element method;
URN: URN:SI:UM:
Type (COBISS): Dissertation
Thesis comment: Univ. v Mariboru, Fak. za strojništvo
Pages: V f., 107 str.
Keywords (UDC): applied sciences;medicine;technology;uporabne znanosti;medicina;tehnika;engineering;technology in general;inženirstvo;tehnologija na splošno;transport vehicle engineering;tehnika vozil;land vehicle engineering (excluding rail vehicles);tehnika kopenskih vozil (razen tirnih);
ID: 1015164