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Investigation of Heat-Affected Zones of Thermite Rail Weldings
(University of Niš, Republic of Serbia, 2024) Fischer, Szabolcs; Harangozó, Dóra; Németh, Dalma; Kocsis, Bence; Sysyn, Mykola; Kurhan, Dmytro; Brautigam, András
ENG: The paper investigates the heat-affected zone (HAZ) of several rail joints executed by thermite rail welding (TW). The examined rail profile was 54E1 (UIC54). The rail steel categories were different: R260 and R400HT. The welding portions of the TWs fitted R350HT and R260 rail categories with normal welding gaps. The rail pieces were brand new, i.e., without any usage in the railway track. The authors executed Vickers-hardness tests (HV10) and material texture tests on the running surface of the rail head, as well as on slices cut from the rail head. The cutting was performed by the water jet method, five longitudinal direction slices with vertical cutting lines. The considered specimen lengths were 2×70 mm (i.e., 70 mm from the mid-point of the rail joint), however, the depths were 20 mm from the running surface. Therefore, the measuring spaces were 5 mm lengthwise and 2 mm in depth. The variation of the hardness values was determined considering the microstructures of the base steel material and the TW. For comparison, previously measured Elektrothermit SoW-5 and earlier own research were taken into consideration.
Numerical Investigation of Pre-Stressed Reinforced Concrete Railway Sleeper for High-Speed Application
(MDPI, 2023) Major, Zoltán; Ibrahim, Sarah Khaleel; Rad, Majid Movahedi; Németh, Attila; Harrach, Dániel; Herczeg, Géza; Szalai, Szabolcs; Kocsis Szürke, Szabolcs; Harangozó, Dóra; Sysyn, Mykola; Kurhan, Dmytro ; Baranyai, Gusztáv; Gáspár, László; Fischer, Szabolcs
ENG: The current paper deals with the numerical investigation of a unique designed pre-stressed reinforced concrete railway sleeper for the design speed of 300 km/h, as well as an axle load of 180 kN. The authors applied different methodologies in their research: traditional hand-made calculations and two types of finite element software. The latter were AxisVM and ABAQUS, respectively. During the calculations, the prestressing loss was not considered. The results from the three methods were compared with each other. The hand-made calculations and the finite element modeling executed by AxisVM software are adequate for determining the mechanical inner forces of the sleeper; however, ABAQUS is appropriate for consideration of enhanced and sophisticated material models, as well as the stress-state of the elements, i.e., concrete, pre-stressed tendons, etc. The authors certified the applicability of these methodologies for performing the dimensioning and design of reinforced concrete railway sleepers with pre-stressing technology. The research team would like to continue their research in an improved manner, taking into consideration real laboratory tests and validating the results from FE modeling, special material models that allow calculation of crackings and their effects in the concrete, and so that the real pattern of the crackings can be measured by GOM Digital Image Correlation (DIC) technology, etc.