Wyniki wyszukiwania - BazTech

1

Study of transitional phenomena in rail vehicle dynamics in relation to the reliability and operational state of the continuous welded rail track in terms of rail joints

Groll Witold, Sowiński Bogdan, Konowrocki Robert

Eksploatacja i Niezawodność

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2023

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Vol. 25, no. 1

art. no. 7

EN

This paper presents the results of experimental and numerical studies on reliability and monitoring issues of railway infrastructure in terms of safety and operation. The state of knowledge concerning methods of assessing track condition, in particular rail joints used in continuous welded rail track of railway lines is described. Experimental results of rail joints used in track transition zones and the results of numerical studies/tests of the rail vehicle-track model are outlined. It is demonstrated, basing on the analyses of the experimental results, that not only should the rail joints used in continuous welded rail track be diagnosed during their acceptance, but also during their operation. It is proven that the currently used methodology for testing welded rail joints applied during acceptance testing of contact track is not fully correct and leads to misinterpretation of the measurement results. Moreover, the results of numerical simulation tests presented in this paper confirm the possibility of diagnosing the condition of rail joints by any vehicle passing over such a track equipped with a suitable system.

2

Suppression of rotating machine shaft-line torsional vibrations by a driving asynchronous motor using two advanced control methods

Hańczur Paweł, Szolc Tomasz, Konowrocki Robert

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 6

art. no. e147925

EN

Many industrial rotating machines driven by asynchronous motors are often affected by detrimental torsional vibrations. In this paper, a method of attenuation of torsional vibrations in such objects is proposed. Here, an asynchronous motor under proper control can simultaneously operate as a source of drive and actuator. Namely, by means of the proper control of motor operation, it is possible to suppress torsional vibrations in the object under study. Using this approach, both transient and steady-state torsional vibrations of the rotating machine drive system can be effectively attenuated, and its precise operational motions can be assured. The theoretical investigations are conducted by means of a structural mechanical model of the drive system and an advanced circuit model of the asynchronous motor controlled using two methods: the direct torque control – space vector modulation (DTC-SVM) and the rotational velocity-controlled torque (RVCT) based on the momentary rotational velocity of the driven machine working tool. From the obtained results it follows that by means of the RVCT technique steady-state torsional vibrations induced harmonically and transient torsional vibrations excited by switching various types of control on and off can be suppressed as effectively as using the advanced vector method DTC-SVM.

3

Identification of safety hazards and operating conditions of the low-floor tram with independently rotating wheels with various drive control algorithms

Konowrocki Robert, Kalinowski Dariusz, Szolc Tomasz, Marczewski Artur

Eksploatacja i Niezawodność

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2021

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Vol. 23, no. 1

21--33

EN

The aim of the article is to develop a method for the analysis of tram dynamics related to safety during operation. To achieve this, a mathematical model of the vehicle represented by a multibody simulation MBS system is used. Models of tram with a classic and innovative drive, based on a system of independently rotating wheels on crank axles are analyzed. A new configuration of an innovative drive control of the considered vehicle with the use of braking of independent wheels is proposed. A new geometry of test track is presented. During numerical investigation the values of ‘Y’ leading forces of tram wheels with the considered innovative drive proved to be lower than in the corresponding vehicle with standard wheelsets. It has been demonstrated that the active control systems are of key importance and should be applied in such innovative tram drives.

4

Research on stability and sensitivity of the rotating machines with overhung rotors to lateral vibrations

Szolc Tomasz, Konowrocki Robert

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e137987

EN

The rotating machines with overhung rotors form a broad class of devices used in many types of industry. For this kind of rotor machine in the paper, there is investigated an inf luence of dynamic and static unbalance of a rotor, parallel and angular misalignments of shafts, and inner anisotropy of rigid couplings on system dynamic responses. The considerations are performed through a hybrid structural model of the machine rotor-shaft system, consisting of continuous beam finite elements and discrete oscillators. Numerical calculations are carried out for parameters characterizing a heavy blower applied in the mining industry. The main goal of the research is to assess the sensitivity of the imperfections mentioned above on excitation severity of rotor-shaft lateral vibrations and motion stability of the machine in question.

5

Analysis of rail vehicles’ operational reliability in the aspect of safety against derailment based on various methods of determining the assessment criterion

Konowrocki Robert, Chojnacki Andrzej

Eksploatacja i Niezawodność

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2020

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Vol. 22, no. 1

73--85

EN

The article features the results of computer and experimental research on operational issues in the aspect of safety in relation to a freight wagon derailment on a railway track. It presents the knowledge regarding the methods of assessing the operational safety of rail vehicles on railroad tracks for the purpose of comparative analysis. The theoretical analyses were performed based on several methods that assess the safety of their derailments, qualifying for operational reliability, comparing them with the results obtained from experimental research. For the purpose of the research, a computer model of rail vehicle- railway track was created. It took into consideration dynamic parameters of elements used in the real track and rail vehicle. The results obtained from theoretical analyses were validated with experimental tests carried out on real objects (freight vehicle - test track, freight wagon - test rig). As part of the research, new test track geometry for testing rail vehicles was proposed. The results obtained in this way allowed estimating the conditions threatening the operation of a freight vehicle while running on the test rail infrastructure with different assessment criteria and to compare them.

PL

W pracy pokazano rezultaty badań komputerowych i eksperymentalnych dotyczących zagadnień eksploatacji w aspekcie bezpieczeństwa w odniesieniu do wykolejenia wagonu towarowego na torze kolejowym. Przybliżono w nim stan wiedzy dotyczącej metod oceny bezpieczeństwa eksploatacji pojazdówa) szynowych na kolejowych liniach szynowych, w celu ich analizy porównawczej. W pracy wykonano analizy teoretyczne bazując na kilku metodach, które oceniają bezpieczeństwo ich wykolejenia, kwalifikujące się do niezawodność eksploatacyjnej, porównując je z wynikami otrzymanymi z badań eksperymentalnych. Na potrzeby przeprowadzanych badań powstał komputerowy model pojazd szynowy - tor kolejowy. Uwzględniał on parametry dynamiczne elementów zastosowanych w rzeczywistym torze oraz pojeździe szynowym. Otrzymane z teoretycznych analiz wyniki zwalidowano testami eksperymentalnymi wykonanymi na rzeczywistych obiektach (pojazd towarowy - tor testowy, wagon towarowy - stanowisko badawcze). W ramach badań zaproponowano nową geometrię toru testowego do badań pojazdów szynowych. Uzyskane wyniki pozwoliły określić stan zagrożenia eksploatacji wagonu towarowego podczas jazdy po testowej infrastrukturze szynowej przy różnych kryteriach oceny oraz je porównać.

6

Modelling of dynamic aspects of operation in railway vehicle traction drive system including the electromechanical coupling

Konowrocki Robert

Zeszyty Naukowe. Transport / Politechnika Śląska

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2019

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z. 105

101--111

EN

In this paper, the influence of electromechanical interaction in an electric motor on the railway vehicle driving system dynamics was investigated. This is the train driven by DC. In particular, there is considered influence of electromagnetic field between a rotor and stator on excitation of resonant torsional vibrations of the drive system. Conclusions drawn from the computational results can be very useful during the design phase of these devices as well as helpful for their users during regular maintenance.

7

A new efficient adaptive control of torsional vibrations induced by switched nonlinear disturbances

Wasilewski Maciej, Pisarski Dominik, Konowrocki Robert, Bajer Czesław I.

International Journal of Applied Mathematics and Computer Science

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2019

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Vol. 29, no. 2

285--303

EN

Torsional vibrations induced in drilling systems are detrimental to the condition of the machine and to the effectiveness of the engineering process. The cause of vibrations is a nonlinear and unknown friction between a drill string and the environment, containing jumps in its characteristics. Nonlinear behaviour of the friction coefficient results in self-excited vibration and causes undesirable stick-slip oscillations. The aim of this paper is to present a novel adaptive technique of controlling vibrating systems. The scheme is based on the linear quadratic regulator and uses direct measurements of the friction torque to synthesize its linear dynamic approximation. This approach allows generating a control law that takes into account the impact of the friction on the system dynamics and optimally steers the system to the desired trajectory. The controller’s performance is examined via numerical simulations of the stabilization of the drilling system. The proposed solution outperforms the comparative LQG regulator in terms of the minimization of the assumed cost functional and the overall stability of the control system under the nonlinear disturbance.