1. Fatigue behaviour of copper-brazed 316L stainless steelJernej Kralj, Blaž Hanželič, Srečko Glodež, Janez Kramberger, Roman Satošek, Branko Nečemer, 2024, original scientific article Abstract: The plate heat exchanger (PHE) is a component that provides heat to be transferred from hot water to domestic cold water with-out mixing them with high efficiency. Over the lifetime of the PHE, cyclic pressure acts on the brazing points and the plates, andthis can lead to fatigue failure. The fatigue behaviour of the PHE, designed by using copper-brazed 316L (also known as 1.4404) stainless steel, was investigated by performing fatigue tests to obtain the S-N curve of the analysed brazed joint. The fatigue tests were performed on a Vibrophore 100 testing machine under the load ratio R= 0.1 for different values of calculated ampli-tude stress. Based on the obtained experimental results, an appropriate material model of the analysed brazed joint was created, which was validated with a numerical calculation in the framework of a program code Ansys. A validated material model canthen be used for the subsequent numerical analysis of the PHE.
Keywords: plate heat exchanger, brazed joint, fatigue, experimental testing
Published in DKUM: 10.04.2025; Views: 0; Downloads: 4
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2. Fatigue behaviour of brazed joints for heat exchangersBlaž Hanželič, Jernej Kralj, Tonica Bončina, Branko Nečemer, Janez Kramberger, Roman Satošek, Srečko Glodež, 2024, original scientific article Abstract: The plate heat exchanger (PHE) is a component that provides heat to be transferred from hot water to domestic cold water without mixing them with high efficiency. Over the lifetime of the PHE, cyclic pressures act on the brazing points and the plates, and this may lead to fatigue failure. The fatigue behaviour of the PHE, designed using copper-brazed 316L stainless steel, was investigated in this study. First, the fatigue tests under the load ratio R = 0.1 were performed on the Vibrophore 100 testing machine to obtain the S-N curve of the analysed brazed joint. Based on the obtained experimental results, an appropriate material model of the analysed brazed joint has been created, which was validated with numerical calculation in the framework of a program code Ansys. A validated material model was then used for the subsequent numerical analysis of PHE. In order to carry out a numerical calculation using the finite element method (FEM), a three-dimensional model of the heat exchanger was created based on the previous scanning of PHE-geometry. Thereafter, the geometry was parameterised, which allowed us to perform parametric simulations (monitoring different responses depending on the input geometry). Numerical simulations were carried out in the framework of the Ansys 2023-R1 software, whereby the obtained results were analysed, and the responses were appropriately characterised according to previously determined load cases.
Keywords: brazed joint, fatigue, experimental testing, computational analyses, heat exchanger
Published in DKUM: 31.01.2024; Views: 316; Downloads: 64
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3. Parametrično modeliranje enostopenjskega zobniškega reduktorja z upoštevanjem koeficientov profilnih premikov : diplomsko deloJernej Kralj, 2021, undergraduate thesis Abstract: Diplomsko delo obsega opis parametričnega modeliranja enostopenjskega zobniškega
reduktorja s poudarkom na modeliranju valjastih zobnikov s poševnim ozobjem, upoštevajoč
vpliv vsote koeficientov profilnih premikov na geometrijo ozobja. Rezultat diplomske naloge je
torej parametričen 3D model zobniškega gonila, katerega geometrija se ustrezno spreminja v
odvisnosti od vrednosti parametrov. Poleg tega so dodane še nekatere nadgradnje, kot so
izračun življenjske dobe raznih strojnih elementov ter izračun površinskih tlakov ipd.
Keywords: parametrično modeliranje, zobniki s poševnim ozobjem, koeficienti profilnih
premikov, strojni elementi, 3D model
Published in DKUM: 11.10.2023; Views: 619; Downloads: 92
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4. Mehanska karakterizacija lotnih spojev toplotnega izmenjevalca : magistrsko deloJernej Kralj, 2023, master's thesis Abstract: V tem delu smo določili vrednosti materialnih parametrov lotnih spojev toplotnega izmenjevalca, ki so namenjeni definiranju materialnih lastnosti pri numeričnih simulacijah z metodo končnih elementov. Na podlagi rezultatov statičnih nateznih testov smo določili vrednost modula elastičnosti, meje tečenja in natezne trdnosti preizkušancev lotnih spojev, prav tako pa smo podali tudi nekaj parametrov, ki opišejo plastični del krivulje σ – ε. Poleg statičnih smo izvajali tudi dinamične teste pri vedno enakem obremenitvenem razmerju in s pomočjo le – teh določili vrednosti koeficienta in eksponenta trdnosti pri utrujanju, ki sta veljavna v območju, ko delovne napetosti ne presegajo vrednosti meje tečenja. Vse pridobljene rezultate smo naknadno tudi potrdili z uporabo numeričnih analiz po metodi končnih elementov v programu Ansys, kjer smo pokazali, da se rezultati ujemajo.
Keywords: toplotni izmenjevalec, lotni spoj, utrujanje, eksperimentalne raziskave, numerične analize.
Published in DKUM: 24.08.2023; Views: 571; Downloads: 0
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