1. Strižna trdnost lotnih spojev toplotnih izmenjevalcevŽan Dvoršak, 2025, master's thesis Abstract: V magistrski nalogi smo obravnavali strižno trdnost lotnih spojev toplotnih izmenjevalcev, ki so bili izdelani iz nerjavnega jekla in spojeni s postopkom vakuumskega lotanja. V okviru naše raziskave so bili izvedeni statični in dinamični strižni testi, katerih rezultati so nam podali materialne lastnosti spoja in S-N diagram življenjske dobe. V nadaljevanju je bila izvedena metalografska analiza na nepretrganem vzorcu in vzorcu s statično ter dinamično obremenitvijo. Pri tem smo izvedli tudi meritev mikrotrdote na osnovnem materialu in v okolici spoja. Na vzorcih, ki so bili utrujani, pa smo izvedli še fraktografsko analizo v kombinaciji z EDS analizo mikrostrukture. S pomočjo analiz smo uspeli povezati mehanske lastnosti spojev z njihovo mikrostrukturo in opredeliti vpliv difuzije, utrjevanja ter morebitnih napak v spoju z njihovo nosilnostjo in življenjsko dobo.
Keywords: toplotni izmenjevalec, lotni spoj, statični in dinamični strižni testi, metalografska analiza, fraktografska analiza, mikrotrdota
Published in DKUM: 11.11.2025; Views: 0; Downloads: 5
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2. Konstruiranje CNC rezkalnega strojaMiha Ribič, 2025, master's thesis Abstract: V magistrski nalogi je predstavljena zasnova in konstrukcija CNC rezkalnega stroja za lastno uporabo. Osnovni cilj je bil razviti cenovno dostopen, a dovolj tog in natančen stroj za obdelavo različnih materialov, predvsem navadnega jekla ter občasno tudi nerjavnega jekla. V uvodnem delu je podan kratek pregled CNC rezkalnih strojev, njihovih značilnosti in področij uporabe. Sledi utemeljitev izbire ključnih komponent, kot so koračni motorji v zaprti zanki, visokofrekvenčno vreteno, kroglična vretena in linearna vodila glede na zahteve obdelave jekla in razmerje med zmogljivostjo in ceno. V zaključku je predstavljen proces 3D modeliranja konstrukcije v programu Creo 8 ter glavne konstrukcijske rešitve, ki zagotavljajo stabilnost in natančnost. Rezultat je tehnično utemeljena in praktično izvedljiva zasnova kompaktnega triosnega CNC rezkalnega stroja, prilagojenega delovanju v manjšem delavniškem okolju.
Keywords: CNC stroj, rezkanje, koračni motor, vreteno, kroglično vreteno, linearna vodila, 3D modeliranje, Creo
Published in DKUM: 15.10.2025; Views: 0; Downloads: 12
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3. Numerical investigation of imperfection-induced secondary bending stresses in box girdersJernej Kralj, Nenad Gubeljak, Srečko Glodež, Janez Kramberger, 2025, original scientific article Abstract: Numerous studies have demonstrated that the initial out-of-plane deflection can significantly affect stress distribution along the web boundaries of steel plate girders, potentially leading to the initiation of fatigue cracks and eventual structural failure over time. Fatigue cracks in thin-walled structures commonly initiate at locations of maximum secondary bending stress, arising from the web imperfections introduced during the complex manufacturing process and further amplified by the interaction of global and local stresses. The secondary bending stress of box girders web plate has been numerically investigated in this article. Several nonlinear static analyses have been performed, using the hybrid parametric FE model, consisting of shell and beam finite elements. Vertical normal stress in the upper web boundary below rail was evaluated under different boundary conditions and geometric modifications. Considering the deflection shape of critical buckling mode 1, the directional effects of initial web imperfection and eccentric moment have been evaluated. Also, a comparison in terms of secondary bending stress at different girder spans, intermediate plate spacing and load positions are discussed. The results of this study offer valuable insights into the most and least favorable scenarios related to geometric modifications and varying loading conditions, while also highlighting existing research gaps in current design codes.
Keywords: box girder, initial web imperfection, out of plane deflection, secondary bending stress, wheel loading
Published in DKUM: 09.07.2025; Views: 0; Downloads: 14
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4. Determination of fracture toughness and resistance curves by three methods on armoured steelMirza Manjgo, Srečko Glodež, Gorazd Lojen, Tomaž Vuherer, 2025, original scientific article Abstract: Parameters of EPFM are used as relevant parameters in structural integrity assessments. In this research, the fracture toughness of armoured steel was determined. The resulting resistance curves and KJIC obtained according to the ASTM E1820 standard with normalization, compliance and multi-specimen methods were compared. Also, the KIC was verified according to the ASTM E399 standard as the most precise method for obtaining the KIC, which also requires a lot of knowledge. For the experiment, the multi-specimen method was used, which is the most expensive and most accurate method, where the least assumption and crack size is measured on the specimen. A fractographic analysis was also presented, and this heat-treated high-strength steel, which is used for anti-ballistic protection, was fully characterized.
Keywords: Protac 500, fracture mechanics, KJIC, resistant curves
Published in DKUM: 03.07.2025; Views: 0; Downloads: 6
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5. Konstruiranje ločevalnika etiket : magistrsko deloAljaž Kerin, 2025, master's thesis Abstract: Magistrska naloga obravnava razvoj ločevalnika etiket, namenjenega sortiranju
odpadkov, ki je bil zasnovan posebej za potrebe podjetja Willy Stadler d. o. o. Proces
modeliranja je bil izveden v programskem okolju Autodesk Inventor, pri čemer so bile
ključne prioritete kompaktnost naprave ter njena splošna učinkovitost v delovanju. V
okviru dela je bila izvedena trdnostna analiza nosilca pnevmatske enote z uporabo
metode končnih elementov. Naloga vključuje tudi izdelavo ločevalnika, izvajanje testiranj
z optimizacijo delovanja ter analizo dobljenih rezultatov. Razvita rešitev ponuja
inovativen pristop k izboljšanju procesov obdelave odpadkov, saj je naprava zasnovana
tako, da se zlahka prilagaja različnim vrstam materialov in prispeva k učinkovitejšemu
recikliranju. Poleg tega je bil poudarek na enostavnosti vzdrževanja in integraciji v
obstoječe proizvodne linije, kar podpira dolgoročno uporabnost in trajnostni razvoj v
podjetju. Projekt tako predstavlja pomemben korak k modernizaciji tehnologij za
upravljanje z odpadki in krepi konkurenčnost podjetja na trgu.
Keywords: konstruiranje, sortirne linije, ločevalnik etiket
Published in DKUM: 20.06.2025; Views: 0; Downloads: 39
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6. Fatigue behaviour of different chiral auxetic structures using a numerical approachBranko Nečemer, Patrik Lampret, Srečko Glodež, 2025, original scientific article Abstract: This study presents the computational analysis for determining the fatigue life of different chiral auxetic structures made of aluminium alloys 5083-H111. The influence of Poisson's ratio on the loading process was investigated to determine which structures exhibited the auxetic effect and how intense it was. Finally, the fatigue life calculation was performed using the strain life approach in the framework of the ANSYS software. The fatigue life determination was evaluated using the approach of amplitude strains, amplitude forces, and strain energy density per cycle. The computational results were described and presented according to predefined approaches, from which it was determined which chiral structure can withstand the highest number of loading cycles at the prescribed load, and which structure shows the most favourable combination of mechanical and physical properties.
Keywords: advanced metamaterials, chiral auxetic structures, fatigue behaviour, numerical simulations, aluminium alloys
Published in DKUM: 20.05.2025; Views: 0; Downloads: 11
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7. Geometrijske in mehanske lastnosti celičnih metamaterialovNejc Novak, Branko Nečemer, 2025, reviewed university, higher education or higher vocational education textbook Abstract: Učbenik z naslovom "Mehanske in geometrijske lastnosti celičnih metamaterialov" je namenjen kot študijsko gradivo pri predavanjih predmetov Konstruiranje s celičnimi gradivi in Dimenzioniranje lahkih konstrukcij za študente Univerze v Mariboru. Učbenik temelji na raziskavah naprednih metamaterialov, ki združujejo edinstvene mehanske in geometrijske lastnosti. Vsebuje pregled sodobnih celičnih metamaterialov in izdelovalnih tehnologij, uporaba eksperimentalnih in numeričnih pristopov, ter izsledke opravljenih raziskav mehanske in geometrijske karakterizacije. Vsebina učbenika je v skladu z učnimi načrti omenjenih predmetov.
Keywords: celični metamateriali, mehanske lastnosti, geometrijske lastnosti, mehansko testiranje, računalniške simulacije
Published in DKUM: 13.05.2025; Views: 0; Downloads: 103
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8. 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: 23
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9. A computational model for analysing the wear behaviour of polymer gearsAljaž Ignatijev, Srečko Glodež, Aleš Belšak, Matej Borovinšek, 2025, original scientific article Abstract: In the presented study, a computational model was developed to analyse the wear behaviour of contacting mechanical elements like gears, bearings, etc. The model was built in the framework of the PrePoMax open-source CalculiX FEM (Finite Element Method) solver and enables a detailed analysis of the meshing dynamics of contacting mechanical elements. The model also considers the hyperelastic behaviour of the material in contact and the impact of operating temperature. The developed computational model was evaluated on a spur gear pair, where the pinion made of POM (Polyoxymethylene) was meshed with a support gear made of case-hardened steel 16MnCr5. The computational results were compared with the analytical results according to the VDI 2736 guidelines and experimental results on the real gear pairs. Compared to the standardised procedure according to the VDI 2736 guidelines, the model's main advantage is the geometry updating after a chosen number of loading cycles, enabling a more accurate prediction of wear behaviour under rolling/sliding loading conditions.
Keywords: wear, polymer gears, computational modelling, experimental testing
Published in DKUM: 08.04.2025; Views: 0; Downloads: 18
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10. Noise evaluation of S-polymer gearsBoštjan Trobentar, Matija Hriberšek, Simon Kulovec, Srečko Glodež, Aleš Belšak, 2022, original scientific article Abstract: In this study, an acoustic behaviour of S-polymer gears made of the material combination
POM/PA66 was investigated and compared to the standardised involute gears (E-gears). Basic
evaluating characteristics included noise during operation, which is of particular significance when
noise reduction is expected. The measured signals were analysed in time and frequency domains
and the levels of acoustic activity were compared. The experimental results have shown that the
sound pressure level of both E- and S-polymer gears are proportional to the torque. However, the
comprehensive noise evaluation has shown some advantages of S-polymer gears if compared to the
E-polymer gears. In that respect, S-polymer gears were found more appropriate for noise reduction
of gear drive systems in the case of normal loading and typical drive speed. Future studies in the
operating behaviour of S-polymer gears could also cover noise evaluation using new methods of
sound signal analysis at different temperatures of gears.
Keywords: polymers, S-gears, sound, noise analysis
Published in DKUM: 24.03.2025; Views: 0; Downloads: 13
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