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    Wyświetlanie 1-6 z 6
    Tytuł:
    Numerical simulation of feedback controlled fluid-induced instabilities in rotor system supported by hydrodynamic bearings
    Autorzy:
    Ferfecki, P.
    Sikora, R.
    Poruba, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/229847.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    rotor system
    hydrodynamic bearing instability
    kinematic excitation
    Opis:
    In certain operating conditions, the oil-film forces, by which the hydrodynamic bearings act on the rotor, destabilize and induce a self-excited vibration. There are many solution based on modifications of the bearing geometry to enlarge the operational range of the hydrodynamic bearing as a tilting pad bearing, lemon bore, etc. or usage of the dampers whose operation is based only on the dissipation of mechanical energy. In this paper several concepts based on controlled kinematic excitation of the bearing shells is investigated by computer simulation and by experimental test. The mathematical model of the uncontrolled and controlled rotor system contains the nonlinear hydrodynamic forces determined by the solution of the Reynolds equation assuming short case of bearing. To solve the equation of motion the Runge-Kutta method of the 4th order with Dormand-Prince modification and variable length of the integration step is used. The computer simulations were performed for rotor system without feedback control and with feedback controller. The main objectives of the numerical analysis were determination of the stability regions of the vibration excited by the imbalance forces. Results of the computer simulations proved that the analyzed approaches reduce amplitude of the rotor vibration caused by the imbalance forces. Experimental test and computer simulations demonstrate that the active vibration control increases considerably the rotation speed when the self-excited vibration of the oil-film occurred.
    Źródło:
    Archives of Control Sciences; 2010, 20, 3; 287-301
    1230-2384
    Pojawia się w:
    Archives of Control Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Synchronization of mechanical oscillators excited kinematically
    Synchronizacja oscylatorów mechanicznych wymuszanych kinematycznie
    Autorzy:
    Perlikowski, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/281780.pdf
    Data publikacji:
    2008
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    synchronizacja
    oscylatory mechaniczne
    pobudzenie kinematyczne
    synchronization
    mechanical oscillators
    kinematic excitation
    Opis:
    In this paper, the behaviour of a system of coupled mechanical oscillators excited kinematically was studied numerically. Several methods of detection of synchronization were shown and advantages of each were mentioned. The relation between Lyapunov exponents and the synchronization state under different kinds of the excitation signal (harmonic, periodic and chaotic ones) was presented. It was demonstrated that the mode locking with excitation was dependent only on inner damping and completely uncorrelated with the connection between oscillators.
    W artykule pokazano numeryczną analizę dynamiki sprzężonych oscylatorów mechanicznych wymuszonych kinematycznie. Przedstawiono przegląd najważniejszych metod detekcji synchronizacji, zwracając szczególną uwagę na ich własności. Następnie opisano powiązania między widmem wykładników Lapunowa, a różnymi typami synchronizacji. Zbadano odpowiedź układu dla różnych typów sygnału wymuszającego (harmonicznego, okresowego i chaotycznego). Udowodniono, że zamykanie modów pomiędzy sygnałem oscylatora a wymuszeniem zależne jest tylko od tłumienia wewnętrznego oscylatorów, natomiast jest niezależne od sprzężeń pomiędzy nimi.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2008, 46, 1; 185-204
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simulation study of the method of random kinematic road excitation’s reconstruction based on suspension dynamic responses with signal disruptions
    Autorzy:
    Klockiewicz, Zbyszko
    Ślaski, Grzegorz
    Spadło, Mikołaj
    Powiązania:
    https://bibliotekanauki.pl/articles/127749.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    suspension
    kinematic excitation
    dynamic responses
    zawieszenie
    wymuszenie kinematyczne
    odpowiedzi dynamiczne
    Opis:
    The paper presents the results of simulation studies of the method of random kinematic road excitation’s reconstruction based on the dynamic responses of the suspension acquired in road tests. The method uses registered unsprung mass accelerations as well as model of suspension’s vertical dynamics and tracking control with PID controller to monitor unsprung mass accelerations’ signal in simulation. In the simulation the quality of reconstruction of random irregularities of the road profile was tested. The road profiles were generated based on their power spectral density of road profile heights that is in line with the description given in ISO 8608 standard. Four road classes had their profiles estimations tested – A, B, C and D (corresponding to highways through city roads to the very bad quality roads). The influence of the simulated noise in the suspension’s dynamic response signal – i.e. unsprung mass acceleration – was also tested. The methods of processing of the initial acceleration’s signal from the road tests were proposed and achieved accuracy was defined. Lastly, the necessary requirements to use the method effectively were defined and its limitations were listed.
    Źródło:
    Vibrations in Physical Systems; 2019, 30, 2; 1-8
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental identification of modal parameters for the model of a building subjected to short-term kinematic excitation
    Autorzy:
    Majcher, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/178609.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    experimental studies
    input-output method
    identification of modal parameters
    kinematic excitation
    Opis:
    In this work, the input-output method of dynamic parameters’ identification is experimentally tested. A method based on the transformation of a dynamic problem into a static problem by means of integration of the input and output signal was presented. The problem discussed in this article is the identification of the coefficients of stiffness matrices and eigenfrequencies of a discrete dynamic system subjected to kinematic input. The experimental analysis was carried out on a three-storey slab-and-column structure, which constitutes a physical model of a building. The vibrations of the model were excited kinematically by an earthquake simulator. The device has a computer-controlled, movable table top, which can move independently in three directions, that is, horizontally, vertically, and rotationally around the vertical axis. The aim of the experimental studies presented in this work was to determine the dynamic parameters of the model (stiffness, natural frequencies) using the input-output method in the time domain. Moreover, the results obtained with this method were compared with the results of experimental modal analysis (EMA) in order to verify their correctness. It was assumed that the movement of the base is horizontal and occurs in one direction. Two short-term, irregular kinematic excitations of the construction were considered, and the selected results and conclusions from experimental analyses were presented in this work.
    Źródło:
    Studia Geotechnica et Mechanica; 2018, 40, 4; 321-332
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The method of estimating kinematic road excitation with use of real suspension responses and model
    Autorzy:
    Klockiewicz, Zbyszko
    Ślaski, Grzegorz
    Powiązania:
    https://bibliotekanauki.pl/articles/127825.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    suspension
    kinematic excitation
    remote parameter control
    simulation
    PID controller
    zawieszenie
    wymuszenie kinematyczne
    zdalna kontrola parametrów
    symulacja
    regulator PID
    Opis:
    The paper deals with the problem of vertical kinematic excitations in road vehicle dynamics simulation, with the main focus on reconstruction of random excitations using measured dynamic responses of a car suspension. The possibility of causing excitations adequately in terms of chosen conditions of exploitation and in reliable way is crucial to properly asses ride comfort, ride safety as well as rattle space and fatigue strength of suspension elements. The paper presents a method of generating equivalent kinematic excitation allowing for reconstruction of suspension dynamic responses in simulation. The method uses unsprung mass accelerations acquired during test rides and a model of vertical suspension dynamics. The method uses estimated displacements of unsprung mass as a preliminary approximation of kinematic excitation and tracking control system with a PID controller, which causes corrections of kinematic excitations transforming it to the form that allows for faithful reconstruction of unsprung mass accelerations and, in turn, kinematic excitations. The paper presents the basic structure of kinematic excitations’ reconstruction system as well as a method of tuning PID controller’s coefficients so that the error in estimation is minimized. Research and verification of results were done using a sine chirp signal and constant frequency sine waves. The similarity of estimated road profiles is high with error no larger than 8% of the original signal’s amplitude.
    Źródło:
    Vibrations in Physical Systems; 2019, 30, 2; 1-10
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modeling and parameter identification of vibrations of a double torsion pendulum with friction
    Autorzy:
    Czerwiński, E.
    Olejnik, P.
    Awrejcewicz, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/387504.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
    Tematy:
    friction
    planar contact
    numerical modeling
    double torsion pendulum
    parameter identification
    nonlinear vibrations
    kinematic excitation
    kinematic forcing mechanism
    nelder-mead method
    tarcie
    modelowanie numeryczne
    wahadło podwójne skręcane
    identyfikacja parametrów
    drgania nieliniowe
    wzbudzanie kinematyczne
    metoda Neldera-Meada
    Opis:
    The purpose of this paper is to investigate a double torsion pendulum with planar frictional contact. The single torsion pendulum with one-degree-of-freedom is an angular equivalent of the linear harmonic oscillator. The second degree of freedom has been obtained by adding a free body to the inverted single torsion pendulum. The free body’s angular displacement is caused by frictional forces appearing in the interface (contact zone) between the free body and the pendulum column’s head kinematically excited at its base by a mechanism with torsion spiral spring. An experimental station has been set up and run to find most unknown parameters of the pendulum from the time series of state variables taken as inputs to the Nelder-Mead method of identification. The obtained results proved significant usability of the identification method in the case of numerical simulation of the pendulum’s dynamical model. It has not been satisfactorily proved in the case of time characteristics coming from a real system that exhibits also some unrecognized physical effects.
    Źródło:
    Acta Mechanica et Automatica; 2015, 9, 4; 204-212
    1898-4088
    2300-5319
    Pojawia się w:
    Acta Mechanica et Automatica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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