Wyniki wyszukiwania - BazTech

1

Fuzzy identification of the reliability state of the mine detecting ship propulsion system

Pająk Michał, Muślewski Łukasz, Landowski Bogdan, Grządziela Andrzej

Polish Maritime Research

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2019

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nr 1

55--64

EN

The study presents the evaluation and comparative analysis of engine shaft line performance in maritime transport ships of the same type. During its operation, a technical system performs functions for which it was designed. It goes through different states. Dynamic state changes of a rotational system can be identified by means of its vibration measurement. For this purpose, a research was carried out which involved recording vibrations of the analysed rotational systems. The recordings were used for calculating selected characteristics in the time-domain, where one of the most unique is the value of the normalized mutual correlation function. On the basis of the concentration values, the characteristics which unambiguously determine the ability state were selected for further studies. Then an identification method for rotational system non-coaxiality was proposed. The method involves using fuzzy clustering. According to this method the values of input signal characteristics were used to formulate fuzzy clusters of system ability and inability states. The method can be used for identifying the current state of the system. The study presents the results of the application of this method in engine turbine shaft lines of minesweepers, with the rotational system selected as an example. It needs to be noted that the efficiency of identifying the operating state of the system with this method is higher than with other methods described in the literature by authors who deal with this issue. The research results have a significant impact on the evaluation of mechanical properties of the studied objects and directly affect operational states of mechanical systems, including those installed in minesweepers, thus determining their reliability.

2

Coupled lateral-torsional vibrations of a symmetric rotor

Chiliński B., Pakowski R., Stanik Z.

Journal of KONES

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2016

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Vol. 23, No. 4

41--47

EN

The paper presents a cross-sectional analysis of dynamics of rotating systems with different characteristics, starting from the search for solutions in an analytical way, and ending with the numerical attempt to verify the results. There is presented a problem of bending and torsional vibrations in rotational systems, using possibly the simplest model of the phenomenon. It is a heavy disk embedded on the deformable massless shaft. The rotor is symmetric and it is assumed that stiffness can be nonlinear. The analysis of vibrations occurring in rotors is made with the use of this model. This is followed by a preliminary discussion on the problem and the conclusions of the pilot studies. There are presented basic problems related to the phenomenon of lateral-torsional coupling in rotational systems with an emphasis on critical states. Formulation of the problem is the conclusion of preliminary part of the paper. Next, there are discussed the selected methods currently used to solve such problems, together with a discussion of their application in this case. In addition, there is discussed a problem of numerical or analytical character of obtained results and the range of using methods in modelling, designing and experimental studies. The next part of the paper focuses on the solution of the model presented in the introduction, using the following analytical or numerical methods: Krylov-Bogolubov, Adams and Runge-Kutta methods. There are presented assumptions, simplifications of the model, technical details of searching for solutions and the results together with a discussion of their correctness. The results, which were obtained from analysis, are polyharmonic. Due to this fact, the spectra of each solution were presented. These aspects are discussed in the context of the solving methods and motion analysis for rotor systems. The whole paper is summarized with a discussion of the results and their confrontation with reality.

3

A proposition of a torsional-bending vibrations modelling of combustion engines

Dąbrowski Z., Chiliński B., Pankiewicz J.

Journal of KONES

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2016

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Vol. 23, No. 4

71--77

EN

The article presents the problem of modelling coupled bending-torsional vibrations in crank systems. Because during the design of modern drive systems a growing number of phenomena are taken into account, model description of such vibrations has a practical meaning. Commonly used models of dynamics of systems assume the independence of torsional and bending vibrations, which leads to simultaneous analysis of transverse and angular vibrations. Further analysis is carried out with the use of superposition principle. Such an approach is justified in the case of quite rigid drive shafts, where vibrations are relatively small. Current trends in the design of reducing weight, reduction of toxic emissions and reducing fuel consumption, lead to the situation where shafts in crank systems become less stiff. Therefore, phenomena neglected earlier may have significant meaning. Analysis of couplings of transverse and torsional vibrations is so important that the occurrence of these phenomena usually leads to new critical states, which may be especially dangerous for engine operation. Considerations on the reasons of the occurrence and kinds of vibration couplings were presented in the introduction of the article. Further part of the article proposes the linear-bending model of the crankshaft, where transverse and angular displacements are dependent. It was tantamount to the assumption of linear relation between the vector of generalized co-ordinates and generalized forces occurring in the system. The next chapter presents the system of equations describing the dynamics of the crankshaft together with a discussion of the co-ordinate system used in the considerations. In addition, there were presented the results of numerical simulations in frequency domain confirming the conclusions taken from the analysis. The whole paper is concluded with synthetic conclusions on the formulated system of equations, simulations and the influence of the coupling on the dynamics of the whole crank system.

4

Identyfikacja parametryczna modelu układu wirującego ze sprzężeniem drgań poprzecznych i skrętnych

Chiliński B.

Przegląd Mechaniczny

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2015

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nr 5

29--34

PL

W artykule przedstawiono zjawisko sprzężenia drgań skrętnych i giętnych występujące w większości układów wirujących. Szczegółowo sklasyfikowano przyczyny zaburzeń momentu obrotowego. Zaproponowano model dynamiczny o wysokim stopniu abstrakcji, uwzględniający zjawiska występujące w wirnikach w sposób kompleksowy Przedstawiono użyte w obliczeniach uproszczenia i wynik ich zastosowania do analizowanego modelu. Opisano podstawy teoretyczne identyfikacji parametrycznej modelu dynamicznego. Posłużyło to do poprawnego wykonania zadania "dostrojenia" modelu do wyników eksperymentalnych. Ponadto zaprezentowano stanowisko badawcze wykonane w celu przeprowadzenia badań eksperymentalnych oraz porównano wyniki modelowania z wynikami badań doświadczalnych.

EN

The article presents the phenomenon of a coupling of torsional and bending vibrations in most rotational systems. The causes of disturbances of rotational moment were clasified in details. Then, a dynamic model with a high level of abstraction was proposed. It included in a complex way the phenomena which occur in rotors. More over; there were presented simplifications used in calculations and the effect of application of these assumptions in the analysed model. Next, theoretical bases of parametric identification of the analysed model were described. It allowed for a proper solution of the task of "tuning in" the model to experimental results. What is more, there was presented a research station which was designed in order to do experimental research. In the end, the comparison of the results of modelling and experimental research was presented. Everything was summed up with a complex conclusion on the calculations and experiments which were carried out.

5

Analiza wpływu niewyrównoważenia statycznego na pomiary drgań poprzecznych wirnika

Chiliński B.

Przegląd Mechaniczny

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2015

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nr 7-8

43--48

PL

Artykuł prezentuje wpływ niewyrównoważenia statycznego na rejestrowane drgania poprzeczne układów wirujących. We wstępie przedstawiono problem pomiaru drgań wirnika. Następnie pokazano model pomiaru drgań giętnych z wykorzystaniem wibrometrów laserowych. Ponadto zaprezentowano użyte w obliczeniach uproszczenia i wynik ich zastosowania do analizowanego modelu. Przedstawiono również wpływ niewyrównoważenia na strukturę widmową drgań. Dalej szczegółowo opisano stanowisko badawcze wykonane w celu przeprowadzenia badań eksperymentalnych. Na koniec przedstawiono porównanie wyników modelowania oraz badań doświadczalnych. Całość została podsumowana syntetycznymi wnioskami na temat przeprowadzonych obliczeń oraz eksperymentów.

EN

The article presents the influence of static unbalance on registered transverse vibrations of vibrating systems. The introduction presents the problem of measurement of rotor vibrations. Then, there was presented a model of measurement of bending vibrations with the use of laser vibrometer. Moreover, there were presented simplifications used in calculations and the result of their implications in the analysed model. What is more, the influence of unbalance on spectral structure of vibrations was shown. Furthermore, the research station built for the purpose of experimental research was described in details. Finally, the comparison of modelling results and experimental research was presented. Everything was summed up with a complex conclusion on the calculations and experiments which were carried out.

6

Analysis of disturbance torque influence on critical state in rotational systems

Chiliński B.

Transport Problems

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2013

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T. 8, z. 4

137--146

EN

Currently most of existing means of transport contains different types of rotational systems. In many cases the dynamics of such rotors substantially can influence exploitation of the whole vehicle. Moreover, in order to minimize mass of the whole object modern construction materials are applied. This causes that the dynamic phenomena may be fundamental of exploitation. The paper presents preliminary analysis of disturbance torque influence on critical state in rotational system. The consideration assumed simple physical object in the form of heavy disk embedded on weightless, elastic shaft. The shaft was supported on two bearings. In particular chapters of paper, path leading from proposition of physical model, by solution of it, to qualitative conclusions about considered object and torque disturbances influence of motion of this system, was presented. In introduction, outline of considered problem and potential opportunities of it, were demonstrated. In the next chapter, physical and mathematical model of the analysed object, was described. Next and also the last but one chapter gives a detailed discussion of mathematical model in the form of nonlinear ordinary differential equations proposed earlier. The first part of the chapter presents the possibility to solve such a problem, then it shows the simplifications which are used. Furthermore, the influence of used simplifications on the shape of analysed problem was demonstrated. Additionally, the possibility of equations solution presented in the paper was discussed. Moreover, the series of interesting properties of analysed system of equations has been shown based on founded approximate solutions. The whole paper was summarized with plans for future work and synthetic conclusions concerning the innovative control method of critical states.

PL

Aktualnie większość istniejących środków transportu zawiera różnego typu układy wirujące. W wielu przypadkach dynamika takich wirników w istotny sposób wpływa na eksploatacje całego pojazdu. Ponadto w celu zminimalizowania masy całego obiektu stosuje się nowoczesne materiały konstrukcyjne. To powoduje, że zjawiska dynamiczne, mogą mieć podstawowe znaczenie eksploatacyjne. Artykuł przedstawia wstępną analizę wpływu zaburzenia momentu skręcającego na stany krytyczne układu wirującego. Do rozważań przyjęto prosty obiekt fizyczny w postaci ciężkiego krążka osadzonego na nieważkim podatnym wale podpartym w dwóch łożyskach. W poszczególnych rozdziałach artykułu przedstawiono drogę prowadzącą od zaproponowania modelu fizycznego, przez jego rozwiązanie do jakościowych wniosków o rozpatrywanym obiekcie i wpływie zaburzenia momentu skręcającego na jego ruch. We wstępie przedstawiono zarys rozpatrywanego problemu oraz potencjalne możliwości wykorzystania opracowanego zagadnienia. W kolejnym rozdziale zaprezentowano model fizyczny oraz matematyczny dla obiektu będącego podstawą niniejszego artykułu. Następny i zarazem przedostatni rozdział w sposób szczegółowy przedstawia dyskusję zaproponowanego wcześniej modelu matematycznego w postaci układu nieliniowych równań różniczkowych zwyczajnych. Na początku rozdziału przedstawiono rozwiązywalność takiego zagadnienia, następnie opisano zastosowane uproszczenia. W dalszym ciągu zademonstrowano wpływ zastosowanych uproszczeń na kształt analizowanych równań. Dodatkowo podjęto dyskusję o możliwości rozwiązania równań przedstawionych w pracy. Ponadto na podstawie znalezionych przybliżonych rozwiązań wykazano szereg ciekawych własności analizowanego układu równań. Całość została podsumowana celami dalszej pracy oraz syntetycznymi wnioskami, dotyczącymi propozycji innowacyjnej metody sterowania stanami krytycznymi.