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 APRIL 2022.

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Thematic Session: Mechanics of rolling element bearings – models and mathematical methods
Guest organizer: Prof. Radoslav N. Tomović, Faculty of Mechanical Engineering in Podgorica, University of Montenegro, Podgorica, Montenegro.

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UTORAK, 05.04.2022. u 17:00, Live stream
Radoslav N. Tomović, Faculty of Mechanical Engineering in Podgorica, University of Montenegro, Podgorica, Montenegro
INTERNAL LOAD DISTRIBUTION OF ROLLING ELEMENT BEARING
Internal load distribution is one of the most important working characteristics of the rolling bearing, which has a direct impact on its dynamic and static load capacity, service life, the accuracy of rotation, vibration characteristics and the like. It is known that the problem of calculating the internal load distribution in bearings with internal radial clearance is very complex. It is a time-varying, nonlinear and statically indeterminate problem, which can only be solved numerically with the use of computers.
In this paper, a new mathematical model for the calculation of load distribution between rolling elements in a rolling bearing with internal radial clearance is presented. The calculation is based on the so-called load distribution factors. Multiplying these factors with the value of the external radial load, we obtain the loads transmitted by individual rolling elements of the bearing.
The values of the load distribution factors can be read from the corresponding tables and diagrams, which makes the model very suitable for practical application. The model gives exact values for the boundary values of the external load, which correspond to the boundary deflection of the bearing when individual rolling elements come into contact with the bearing rings. For these bearing boundary positions, the load factor values are derived separately for the ball bearing, especially for the roller bearing. For positions that do not correspond to the boundary values of the bearing deflection, the load factors are best determined by interpolation. The new model was compared with up to now the most commonly used models. The case study showed greater accuracy of the proposed model.
The model proposed in this paper takes into account the influence of the size of the internal clearance on the load distribution within the bearing. This influence is expressed through the number of active rolling elements. In that sense, it is proposed to correct the Stribeck number in relation to the number of active rolling elements in the bearing.
Determination of the number of the active rolling elements participating in the transfer of the external load is one of the biggest problems in the calculation of load distribution of rolling bearing. So far, this problem was resolved by trial and error, with a huge number of iterations in solving the static equations until a satisfying solution is obtained. The procedure proposed by the new model allows direct determination of the number of active rolling elements from the diagram in relation to the bearing type, applied load and internal radial clearance.

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UTORAK, 12.04.2022. u 17:00, Live stream
Dragan Milčić, Vladislav Krstić, Faculty of Mechanical Engineering, University of Niš, Niš, Serbia; School of Engineering Management, University Union - Nikola Tesla, Serbia
INVESTIGATION OF THE REFERENCE SPEED OF AXIAL ANGULAR CONTACT BALL BEARINGS INTENDED FOR THREADED SPINDLES
From the very beginning, Paradigm Industry 4.0 has set very strict requirements for the future way of doing business, but also for the way of life. As such, it represents a fusion of advanced technologies such as artificial intelligence, Big Data, virtual reality, augmented reality, cyber-physical systems, additive technologies, genetic engineering, quantum computing, nanotechnology, etc. As a special segment of Industry 4.0, production can be singled out with all its features and requirements. In this sense, Industry 4.0 has a very intense impact in terms of greater flexibility of production systems as well as the greatest degree of automation and robotization of production processes.
Due to these requirements, designers of machine systems (machines) intended for the Industry 4.0 concept strive to optimize the construction and structural elements of machines as much as possible. That is why an increasing number of machines contain a threaded spindle, which is a reliable and relatively simple machine element in terms of construction.
The topic of this lecture is based on roller bearings intended forthreaded spindles. The focus of the lecture is on the bearings of the ZKLN and ZKLF series of the German manufacturer Schaeffler-INA. Main requests for the threaded spindles are high number of revolutions and high accuracy of guidance, this is expected to increase friction that generates thermal energy that spreads through the bearing elements to the system, where it is extremely important that the amount of generated heat does not exceed the allowable limits. Otherwise there may be elastic and in extreme cases plastic deformations of the system elements (eg threaded spindle, damage to roller bearings, etc.). In order to be able to estimate the generated thermal energy of the mentioned types of bearings in the design phase and to define the guidelines and relevant parameters for the selection of roller bearings, a research was done, which is the subject of this lecture.

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UTORAK, 19.04.2022. u 17:00, Live stream
Aleksandar Živković, Mirjana Bojanić-Šejat, Milan Rackov, Ivan Knežević, University of Novi Sad, Faculty of technical sciences, Novi Sad, Serbia
A NEW APPROACH TO MONITORING THE CONDITION AND DETERMINING OF THE ROLLING BEARINGS LIFE
The key principle of Industry 4.0 is increasing the process knowledge through data collection and monitoring. This knowledge can be applied for process control, process optimization and maintenance. On the other hand, the collected data can be integrated with the "digital twin" in order to improve the process. For a long time, the practice of continuous monitoring of machines and systems is applied within the predictive maintenance of responsible and complex systems. In this way, the condition of the machine is continuously monitored and potential problems or damages are detected in time, so the maintenance procedure is adjusted to the observed machine. Rolling bearings are one of the most frequently installed components of machines, although they are (un)justifiably considered the most common "culprits" for unplanned delays and accidents.
The presented research is primarily based on the system for monitoring and data collecting of the roller bearings condition. The system includes continuous monitoring of the bearing condition using temperature and vibration measuring equipment. The measurement data were analyzed using artificial intelligence methods and finite elements. The second part of the presented research refers to the development of the bearings digital model, that is determining the bearing life based on data collected from physical bearings. Both parts of the research are the main components for the development of the "digital machine twin". The digital twin provides the ability to interact with a real machine. The possibility to combine real data with simulation models provides a new range of applications with clear advantages. One of the advantages is reflected in the monitoring of the machine condition based on visualization and operating simulation using the data from the real machine. Therefore, preconditions are being created for Smart maintenance technologies. In that way, machine failures are prevented in time, which eliminates or excludes unplanned and expensive delays in the production process.

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Obavezno je nošenje maski i održavanje distance. Broj prisutnih na predavanju ograničen na najviše 10 (uključujući i predavača).

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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