1. A computational model for analysing the dry rolling/sliding wear behaviour of polymer gears made of POMAljaž Ignatijev, Matej Borovinšek, Srečko Glodež, 2024, original scientific article Abstract: This study presents a computational model to determine the wear behaviour of polymer gears. Using PrePoMax finite element numerical calculation software, a proposed computational model was built to predict dry rolling/sliding wear behaviour based on Archard’s wear model. This allows the calculation of the wear depth in each loading cycle with constant mesh updating using the finite element method. The developed computational model has been evaluated on a spur gear pair, where the pinion made of POM was meshed with a support gear made of steel. The computational results obtained were compared with the analytical results according to the VDI 2736 guidelines. Based on this comparison, it was concluded that the proposed computational model could be used to simulate the wear behaviour of contacting mechanical elements like gears, bearings, etc. The main advantage of the model, if compared to the standardised procedure according to the VDI 2736 guidelines, is the geometry updating after a chosen number of loading cycles, which enables a more accurate prediction of wear behaviour under rolling/sliding loading conditions. Keywords: polymer gears, rolling/sliding contact, wear, computational modelling Published in DKUM: 12.04.2024; Views: 189; Downloads: 19
Full text (3,67 MB) This document has many files! More... |
2. Innovative approaches to wear reduction in horizontal powder screw conveyors : a design of experiments-guided numerical studyMarko Motaln, Tone Lerher, 2024, original scientific article Abstract: Numerical simulations play a vital role in the modern engineering industry, especially when faced with interconnected challenges such as particle interactions and the structural integrity of conveyor systems. This article focuses on the handling of materials and emphasizes the importance of using parametric numerical analysis to improve efficiency, reduce wear, and enhance the structural integrity of horizontal screw conveyors. Through the utilization of the Design of Experiments, we systematically investigated critical parameters such as screw pitch, clearance, wear, rotational velocity, and additional structural factors. This examination was carried out within a well-defined parametric framework, utilizing a combination of software tools provided by the Ansys suite and Minitab. The findings demonstrate the effectiveness of the Design of Experiments analysis in achieving improved performance and provide valuable insights for engineers and researchers involved in the design of conveyor systems. Furthermore, this comprehensive approach clarifies how conveyor systems respond to changes in parameters and highlights the complex interaction between transported particles and the conveyor system. We present a detailed analysis that clarifies the complex relationships and dependencies among different parameters, providing engineers and researchers with valuable insights. By understanding the interactions of these factors, the methodology provides not only results but also a strategic framework for advancing conveyor system design and engineering practices. Keywords: discrete element method, design optimization, horizontal screw conveyors, parametric study, conveying equipment, bulk handling, bulk solids, abrasive wear, screw conveyor, FEA, performance analysis Published in DKUM: 09.04.2024; Views: 275; Downloads: 44
Full text (10,51 MB) This document has many files! More... |
3. Influence of Al2O3 nanoparticles addition in ZA-27 alloy-based nanocomposites and soft computing predictionAleksandar Vencl, Petr Svoboda, Simon Klančnik, Adrian But, Miloš Vorkapić, Marta Harničárová, Blaža Stojanović, 2023, original scientific article Abstract: Three different and very small amounts of alumina (0.2, 0.3 and 0.5 wt. %) in two sizes (approx. 25 and 100 nm) were used to enhance the wear characteristics of ZA-27 alloy-based nanocomposites. Production was realised through mechanical alloying in pre-processing and compocasting processes. Wear tests were under lubricated sliding conditions on a block-on-disc tribometer, at two sliding speeds (0.25 and 1 m/s), two normal loads (40 and 100 N) and a sliding distance of 1000 m. Experimental results were analysed by applying the response surface methodology (RSM) and a suitable mathematical model for the wear rate of tested nanocomposites was developed. Appropriate wear maps were constructed and the wear mechanism is discussed in this paper. The accuracy of the prediction was evaluated with the use of an artificial neural network (ANN). The architecture of the used ANN was 4-5-1 and the obtained overall regression coefficient was 0.98729. The comparison of the predicting methods showed that ANN is more efficient in predicting wear. Keywords: ZA-27 alloy, Al2O3 nanoparticles, nanocomposites, wear, response surface methodology, artificial neural network Published in DKUM: 20.03.2024; Views: 239; Downloads: 11
Full text (14,10 MB) This document has many files! More... |
4. Numerical simulation of conveying fine powders in a screw conveyor using the discrete element methodMarko Motaln, Tone Lerher, 2023, original scientific article Abstract: Due to their high efficiency and spatial utilization, screw conveyors are widely used in pharmacy, agriculture, and industry. Recently, this has made it a popular research subject in the numerical modelling of the transport of bulk solids. Modelling of granular systems at the level of individual particles is mainly possible due to the use of discrete numerical methods. The most common is the use of the Discrete Element Method (DEM), which is still limited from the point of view of simulations on an industrial scale, as increasing the size of the system also increases the cost of simulation. Certain powders with low density, large angles of repose, poor fluidity, and bad flowability can accumulate during transportation, causing inaccurate and non-uniform movement. Additionally, the friction and impact between the particles can cause wear. To address these issues, the present study utilizes the discrete element method to simulate and analyse powder transportation in an inclined screw conveyor using the commercial software ANSYS-ROCKY. Numerous phenomena that arise while transporting and feeding small-sized or irregularly shaped particles, often present in industrial processes, remain insufficiently investigated. This paper aims to analyse the transportation process of adhesive powders in a screw conveyor, with a focus on evaluating the impact of different screw blade speeds on transport. Multiple simulations were conducted, along with the implementation of an additional wear model, to better understand the transport phenomena and wear. An example was used to demonstrate the impact of screw speed on the wear of the transporter due to the interaction between the material and the structure of the conveyor, power consumption, and performance. Keywords: abrasive wear, bulk handling, coarse graining, conveying equipment, discrete element method, screw conveyor Published in DKUM: 12.09.2023; Views: 457; Downloads: 68
Full text (1,69 MB) This document has many files! More... |
5. Wear Behaviour of Multilayer Al-PVD-Coated Polymer GearsTonica Bončina, Brigita Polanec, Franc Zupanič, Srečko Glodež, 2022, original scientific article Abstract: A comprehensive experimental investigation of the wear behaviour of coated spur polymer gears made of POM is performed in this study. Three different thicknesses of aluminium (Al) coatings were investigated and deposited by the Physical Vapour Deposition (PVD) process. The Al coating was deposited in three steps: By plasma activation, metallisation of the aluminium by the magnetron sputtering process, and plasma polymerisation. The wear of the gears was tested on an in-house developed testing rig for different torques (16, 20, and 24 Nm) and a rotational speed of 1000 rpm. The duration of the experiments was set to 13 h, when the tooth thickness and, consequently, the wear of the tooth flank were recorded. The experimental results showed that the influence of metallisation with aluminium surface coatings on the wear behaviour of the analysed polymer gear is not significantly important. The results also showed that the gears with a thicker aluminium coating showed greater wear than gears with a thinner coating or even without a coating. This is probably due to the fact that the aluminium particles that started to deviate during gear operation represented the abrasive material, which led to the faster wear of the contacting surfaces of the meshing gear flanks. Keywords: polymer gears, aluminium PVD coating, Physical Vapour Deposition process, multilayer coating, wear Published in DKUM: 15.11.2022; Views: 580; Downloads: 80
Full text (13,01 MB) This document has many files! More... |
6. Razvoj aplikacij na platformi android wearŽiga Vehovec, 2017, undergraduate thesis Abstract: V diplomskem delu predstavimo pomen nosljivih tehnologij in se osredotočimo na razvoj aplikacij za pametne ure, ki jih poganja Googlov operacijski sistem Android Wear. Predstavimo, kaj platforma omogoča ter njene pomanjkljivosti in omejitve. Z usvojenim znanjem nato razvijemo aplikacijo, ki uporablja vse glavne koncepte razvoja na omenjeni platformi ter prikaže povezavo med platformama Android in Android Wear. Keywords: Nosljive tehnologije, Android, Android Wear, Pametne ure Published in DKUM: 27.10.2017; Views: 2074; Downloads: 148
Full text (2,59 MB) |
7. Casting process optimization by the regression analysis applied on the wear resistant parts moldingRadomir Slavković, Slavko Arsovski, Aleksandar Veg, Zvonimir Jugović, Aleksandar Jovićić, Nedeljko Dučić, 2012, original scientific article Abstract: Conducting a comprehensive research of the casting process of wear resistant parts (white hard casting), a significant correlation is established between the technological parameters (temperature, aging time in the mold and coolant flow) and the final product hardness. The fundamental theory of Box-Wilson's gradient method marked the baseline for the foreseen researches. The method defines the coherence of the process parameters, since their dispersion in the examined process is relatively small. Main target of the experiment was a definition of the optimal casting conditions. Therefore the different technological routes are identified and the casting process is modified until the best outcome is achieved. Target function was initially in a hypothesized form, while later on evolved into a consistent form due to the application of experiment-statistics, process optimization and process management based on empirical feedback. Keywords: casting, mathematical model, quality management, wear resistance Published in DKUM: 11.07.2017; Views: 1231; Downloads: 123
Full text (595,79 KB) This document has many files! More... |
8. Simulation of the casting process - a powerfull tool for enchanced design of the cutting teeth in surface miningRadomir Slavković, Zvonimir Jugović, Dražan Kozak, Aleksandar Veg, Radomir Radiša, Snežana Dragićević, Marko Popović, 2013, original scientific article Abstract: Recent development in the computer simulation technology caused a tremendous influence on a rapid prototyping in casting process. These computational tools facilitate engineering work and urge moulding verification in foundries. Among dedicated software packages the MAGMASoft is selected for availability reasons. Its effectiveness is proved with the simulation of moulding process of the cutting teeth for a bucket wheel excavator Use of MAGMASoft enables a shortcut to a forceful and durable product, without internal cavities and micro-porosity. Such advancement of the moulding process is described in this paper. Keywords: casting, porosity, wear, simulation, MAGMASoft Published in DKUM: 03.07.2017; Views: 2340; Downloads: 145
Full text (1,03 MB) This document has many files! More... |
9. Realno-časovna komunikacija mobilnih aplikacij s senzorjiTomaž Orter, 2016, undergraduate thesis Abstract: V diplomskem delu predstavimo tehnologije in protokole, ki omogočajo realno-časovno komunikacijo med mobilnimi aplikacijami in senzorji. Z uporabo protokola MQTT na praktičnem primeru nadzora ogrevanja stanovanja predstavimo njihovo uporabnost in lastnosti.
Začnemo z izdelavo senzorja temperature, ki podatke zaznava in sporoča, ter centralnega strežnika, ki jih obdela, se na njih odzove in jih posreduje do končnega odjemalca. Nadaljujemo z izdelavo mobilne aplikacije, ki v tem primeru predstavlja končnega odjemalca. Aplikacija podatke v realnem času prikazuje in uporabniku omogoča nadzor nad ogrevanjem. Mobilno aplikacijo dopolnimo z izdelavo aplikacije za pametno uro. Ta s pomočjo obvestil in lokacijskih podatkov uporabnika opozori na vklop ali izklop varčnega načina ogrevanja. V zaključku dela preverimo, ali smo z uporabo namenske tehnologije uspeli prihraniti na količini prenesenih podatkov in pohitriti njihovo prejemanje. Keywords: Realno-časovna komunikacija, senzorji, internet stvari, nadzor ogrevanja, mobilna aplikacija, MQTT, HTTP, CoAP, AMQP, XMPP, DDS, WiFi, Raspberry Pi, Arduino, Android Wear Published in DKUM: 08.09.2016; Views: 1950; Downloads: 184
Full text (4,05 MB) |
10. |