SCIDAR Collection:
https://scidar.kg.ac.rs/handle/123456789/8211
2024-03-20T08:24:33ZDevelopment of methodology for continuous measurement of wheel-rail contact forces at Faculty of Mechanical and Civil Engineering in Kraljevo
https://scidar.kg.ac.rs/handle/123456789/20325
Title: Development of methodology for continuous measurement of wheel-rail contact forces at Faculty of Mechanical and Civil Engineering in Kraljevo
Authors: Bižić, Milan
Abstract: The key influential parameters and indicators of the quality of the dynamic behavior and stability of movement of railway vehicles are the lateral force Y and the vertical force Q in the wheel-rail interaction, i.e. their ratio Y/Q. The focus of this lesson is the development of a unique method for the experimental determination of wheel-rail interaction forces using an instrumented wheelset. In addition to determining forces in the process of certification and testing of running stability of railway vehicles which is defined by the relevant international standards UIC 518 and EN 14363, developed method enables experimental determination of the contact point position between wheel and rail. Based on the formed numerical model of the wheel, the ways of solving of key problems in development of instrumented wheelsets are defined. They are related to the determination of optimal locations, layout, number and connection of strain gauges, as well as the development of the inverse identification algorithm. Based on the results of testing using a numerical model of the wheel, the high accuracy of the developed method and inverse identification algorithm which is based on the method of blind signal separation (BSS) using independent component analysis (ICA), is founded. Deviations between the wheel-rail interaction parameters obtained using the developed algorithm and really placed parameters in the numerical model are in range of 2 %, while the measurement error that stems from the imperfections of the algorithm lies in the range of 0.5 %. In order to validate the developed method and inverse identification algorithm, the experimental tests on the real object are also performed. The instrumented wheelset of measuring system MEROSA and special test stand M10.09 production OSS (Optical sensor systems, Belgrade, Serbia) are used. Signal-to-noise ratio is identified as the main parameter influencing the accuracy of experimental determination of the wheel-rail interaction forces and contact point position using the developed method. The developed method enables measurement of vertical force Q, lateral forces Y, as well as the ratio Y/Q, with an errors that are in the range of 10 %, while the error of measurement of contact point position is in the range of 15 %. At the flange contact and the higher values of ratio Y/Q or Y force, these measurement errors are reduced, which is extremely important for reliability and quality of assessment of safety against derailment according to the standards mentioned. Experimental tests confirm that developed method is very applicable in the development of instrumented wheelsets and enables highly accurate determination of parameters in the wheel-rail interaction, with measurement accuracy that is in the range of the most contemporary world solutions.
Description: Abstract2023-01-01T00:00:00ZUticaj različitih vrsta krupnog agregata na otpornost betona na habanje brušenjem
https://scidar.kg.ac.rs/handle/123456789/20324
Title: Uticaj različitih vrsta krupnog agregata na otpornost betona na habanje brušenjem
Authors: Topličić-Ćurčić G.; Grdic, Zoran; Ristic, Nenad; Despotovic, Iva
Abstract: Otpornost betona na habanje brušenjem ima značajnu ulogu pri izradi betonskih ploča za popločavanje trotoara tj. pešačkih zona, betonskih kolovoza, industrijskih podova i drugog. U radu je dat prikaz eksperimentalnog istraživanja uticaja različitih vrsta krupnog drobljenog mineralnog agregata na otpornost betona na habanje brušenjem. Spravljene su betonske mešavine sa četiri vrste drobljenog mineralnog agregata: krečnjakom, andezitom, dijabazom i bazaltom. Takođe je data zavisnost između otpornosti betona na habanje brušenjem u odnosu na vodocementni faktor i čvrstoću pri pritisku.2010-01-01T00:00:00ZCONCRETE PAVING BLOCKS AND FLAGS MADE WITH RECYCLED AGGREGATE FROM PRECAST ELEMENTSTHE
https://scidar.kg.ac.rs/handle/123456789/20323
Title: CONCRETE PAVING BLOCKS AND FLAGS MADE WITH RECYCLED AGGREGATE FROM PRECAST ELEMENTSTHE
Authors: Janković, Ksenija; Bojović, Dragan; Stojanović, Marko; Despotovic, Iva; Lončar, Ljiljana
Abstract: The possibility of using recycled aggregate from precast paving blocks and curbs in the production of concrete elements for the pedestrian areas is shown in this paper. Experimental work has included few types of concrete made with different amounts of cement and recycled concrete aggregate. Based on the testing results it was assumed that it is possible to produce the concrete paving blocks and flags comply with European standards. The results show that replacing natural aggregate with crushed concrete aggregate produces concrete elements which meet the requirements of EN 1338 and EN 1339, but class depends of percent of replacement natural aggregate by recycled.2018-01-01T00:00:00ZInfluence of different mineral additives and recycled concrete aggregates on the properties of self – compacting concrete in the fresh state
https://scidar.kg.ac.rs/handle/123456789/20322
Title: Influence of different mineral additives and recycled concrete aggregates on the properties of self – compacting concrete in the fresh state
Authors: Despotovic, Iva; Janković, Ksenija
Abstract: Construction industry uses vast amounts of natural resources, simultaneously producing significant amounts of construction waste, so that it has a great impact on the environment. Self-compacting concrete contains a certain amount of powdered materials – fillers. There are various possibilities of selecting this component. If we used any of the industrial by-products, such as fly ash or silica fume, we would solve the problem of depositing these materials, and thus made concrete ecological material. The research subject presented in this paper are the properties and technology of self-compacting concrete in the fresh state, made with various mineral additives: lime, fly ash, and silica fume, wherein the aggregates used, are both natural and recycled aggregates, obtained by demolition of retaining wall, whose amount is varied in the concrete.2017-01-01T00:00:00Z