Seminar Mechanics of Machines and Mechanisms - Models and Mathematical Methods

 

PROGRAM

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Plan rada Seminara Mehanika mašina i mehanizama - modeli i matematičke metode za NOVEMBAR 2023.

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Ukoliko želite da učestvujete u radu seminara ili da postavite pitanja na kraju predavanja, a još niste registrovani na miteam platformi Matematičkog instituta, možete se registrovati popunjavanjem forme:
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Utorak, 14.11.2023. u 17:00, sala 301f, Kneza Mihaila 36 i Live stream
Jovana Stojić, Faculty of Mechanical Engineering, University of Belgrade, Serbia
COMPUTATIONAL IMPLEMENTATION AND VALIDATION OF CONSTITUTIVE MODELS FOR HEAT RESISTANT DEVICES
Over the past century, the growing demand for steel has raised environmental concerns due to its impact, including air and water pollution, as well as hazardous waste. Refractories play a crucial role in steel manufacturing, requiring reliable models to understand their performance under specified conditions. By comparing various modeling approaches, it is aimed to simulate the behavior of the refractory materials across different temperature ranges. These models are integrated into numerical codes, calibrated with experimental data and further validated. The ultimate goal is to create a versatile material model considering viscosity, damage, and thermoplastic effects for diverse ceramic mixes used in industrial processes.
The present research is supported by the EU within the H2020-ITN-REFRACTURE2 research project.

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Utorak, 28.11.2023. u 17:00, sala 301f, Kneza Mihaila 36 i Live stream
Milan Bižić, Faculty of Mechanical and Civil Engineering in Kraljevo, University of Kragujevac, Serbia
DEVELOPMENT OF METHODOLOGY FOR CONTINUOUS MEASUREMENT OF WHEEL-RAIL CONTACT FORCES AT FACULTY OF MECHANICAL AND CIVIL ENGINEERING IN KRALJEVO
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.

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Seminar Mehanika mašina i mehanizama - modeli i matematičke metode započeo je sa radom u junu 2018.god. Seminar se održava do dva puta mesečno, utorkom u periodu od 17.00 - 19.00 u Matematičkom institutu SANU.

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