Wydział Mechaniczny / Faculty of Mechanical Engineering / W1

Stały URI zbioruhttp://hdl.handle.net/11652/1

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2007 - 200912010 - 201972020 - 20211

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Teraz wyświetlane 1 - 9 z 9
  • Pozycja
    Construction and 3D model of stand for investigating a non-ideal forcing in a nonlinear chain dynamics of self-excited oscillators with friction
    (Wydawnictwo Politechniki Łódzkiej, 2021) Rogala, Patryk; Olejnik, Paweł; Awrejcewicz, Jan
    The research involves application and research on a non-ideal forcing to modelling and identification of vibrating systems with friction. It is still an innovative approach in the numerical analysis of vibrations of mechatronic machines and devices. This will allow to make a much real numerical modelling and more efficient identification of nonlinear dynamic phenomena observed in vibrating systems with friction, and thus, a better modelling of such phenomena in computer programs. To obtain the goal, initial 3D model of the mechanical stand was made in the CAD software. Based on the 3D model, real stand will be built, and experiments will be held to obtain data that will be necessary to ensure correctness of the mathematical model, which also will be studied and developed.
  • Pozycja
    Synchronization in arrays of coupled self-induced friction oscillators
    (Springer, 2016-11) Marszal, Michał; Saha, Ashesh; Jankowski, Krzysztof; Stefański, Andrzej; Katedra Dynamiki Maszyn. Wydział Mechaniczny. Politechnika Łódzka.; Division of Dynamics. Faculty of Mechanical Engineering. Lodz University of Technology.
    We investigate synchronization phenomena in systems of self-induced dry friction oscillators with kinematic excitation coupled by linear springs. Friction force is modelled according to exponential model. Initially, a single degree of freedom mass-spring system on a moving belt is considered to check the type of motion of the system (periodic, non-periodic). Then the system is coupled in chain of identical oscillators starting from two, up to four oscillators. A reference probe of two coupled oscillators is applied in order to detect synchronization thresholds for both periodic and non-periodic motion of the system. The master stability function is applied to predict the synchronization thresholds for longer chains of oscillators basing on two oscillator probe. It is shown that synchronization is possible both for three and four coupled oscillators under certain circumstances. Our results confirmed that this technique can be also applied for the systems with discontinuities.
  • Pozycja
    Metody numeryczne rozwiązywania, analizy i kontroli nieciągłych układów dynamicznych.
    (Wydawnictwo Politechniki Łódzkiej, 2013) Olejnik, Paweł
    Praca przedstawia opis metod matematycznych i procedur numerycznych służących do rozwiązywania zagadnień modelowania i sterowania nieciągłych układów dynamicznych. Uzyskanie pożądanej dokładności rozwiązania równań różniczkowych modelujących stan układu dynamicznego z tarciem, niejednoznacznością parametrów lub opóźnieniem czasowym wymaga stosowania metod dedykowanych. Rozwiązywanie i analiza układów nieciągłych związana z poprawa wydajności metod numerycznych odkrywa istniejący zakres trudności, wyodrębniając interesujące oszacowania i wyprowadzenia matematyczne opisane w tej monografii. Pozwala to na lepsze zrozumienie i dokładniejsze przybliżenie procesów fizycznych zachodzących w rzeczywistych układach drgających.
  • Pozycja
    On the clutch dynamics with the approximations of resulting contact forces.
    (Politechnika Łódzka. Wydział Mechaniczny. Katedra Automatyki, Biomechaniki i Mechatroniki., 2015) Wojtunik, Igor; Szewc, Michał; Kudra, Grzegorz; Awrejcewicz, Jan
    The aim of the work is to present effectiveness of numerical simulations of clutch with frictional contacts, elaborated by some of the current articles in the last few years. The friction models assumes full developed sliding and the classical Coulomb friction law on each element of the contact with general shape and any pressure distribution. Then special modification of the integral model of friction force and moment are proposed. The approximants based on Padé approximants and their generalizations. In the work the clutch dynamics with contacts forces model is presented. The system was simplified to friction disk on rotating master disk. Two different configurations are investigated: coaxial and non-coaxial arrangement of the two disks. For the appropriate rotations speed, the system of non-coaxial arrangement can exhibit the ability to self-centering. The models based on generalizations of Padé approximants are compared with the simulation results obtained by the use of approximants based on Taylor’s expansion and models with exact integral expressions for friction force and torque components.
  • Pozycja
    Model of the gas journal bearing dynamics with a exibly supported foil.
    (Politechnika Łódzka. Wydział Mechaniczny. Katedra Automatyki, Biomechaniki i Mechatroniki., 2015) Tkacz, Eliza; Kozanecki, Zbigniew; Kozanecka, Dorota; Łagodziński, Jakub
    The work is devoted to an analysis of the journal bearing dynamics employing a numerical model which takes into account factors related to motion and friction of non{rotating elements of the sleeve. This model yields the basis for simulations carried out in order to determine correctly dynamic characteristics of an oil{free machine rotating system at the early stage of its design and during its operation. On the basis of those simulations, the thickness of gas lm was determined as well as the pressure distribution in the bearing and its lift capacity. Moreover, the numerical program led to an analysis of proper vibrations and forced vibrations of the system under consideration. It was possible to obtain attenuation of the force and to visualize a journal trajectory for the dynamic harmonic input function. The FFT (Fast Fourier Transform) analysis of vibrations was implemented. In the spectrum, only a frequency of the input function was observed, whereas and a lack of subsynchronous frequencies pointed to the stable operation of the bearing.
  • Pozycja
    Dynamics simulations of a rigid body lying on a vibrating table with the use of special approximations of the resulting contact forces.
    (Politechnika Łódzka. Wydział Mechaniczny. Katedra Automatyki, Biomechaniki i Mechatroniki., 2015) Szewc, Michał; Wojtunik, Igor; Kudra, Grzegorz; Awrejcewicz, Jan
    The work presents simulations and dynamics of a rigid body lying on a vibrating table. An attempt of shaping and control the body dynamical behavior, by the use of manipulation of parameters of the table oscillations, is presented. This work is also an implementation of the specially prepared mathematical models of friction between table and the moving body. Those models are based on the integral model assuming the fully developed sliding on the plane contact area with the foundation of any pressure distribution. In order to simplify the calculations and reduce their computational cost, special approximations of the integral models of friction force and moment are used. They are based on Padé approximants and their generalizations.
  • Pozycja
    Terms of geometric action of rotating ball follower
    (2014) Kuchar, Maciej
    The operation of a new rotating ball follower is presented. The influence of the values of the selected geometrical parameters of the rotating ball follower by simulation are analyzed. The ranges of value of these parameters ensuring correct operation of the rotating ball follower are defined. The operation of the rotating ball follower in real conditions are verified.
  • Pozycja
    Occurrence of strick-slip phenomenon.
    (Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej, 2007) Awrejcewicz, Jan; Olejnik, Paweł
    A self-excited system wit h unilateral friction contact modelled by a two degrees-of-freedom mechanical system, where the normaI farce varies during displacement of a block has been studied. The constructed real laboratory rig approximates the investigated system, and it includes feedback reinforcement of the friction force acting on the vibrated block. Some methods of data acquisition and data handling procedures are proposed for experimentally observed results and data collection. A novel static friction force model for both positive and negative velocities of the base is proposed.
  • Pozycja
    Modelowanie dynamiki kostek domina.
    (Stowarzyszenie Inżynierów i Techników Mechaników Polskich, 2012) Kazimierska-Grębosz, Marianna; Lubnauer, Włodzimierz
    W artykule przedstawiono badania dynamiki łańcucha kostek domina i komputerowe symulacje ich ruchu w układzie 2D. W procesie analizy ruchu kostek badano efekt ich rotacji, zderzania się i tarcia. Przedstawiono wyniki symulacji wirtualnych z wykorzystaniem programu Working Model®. Rezultaty badań numerycznych pokazano w postaci faz ruchu kostek.