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EN
Vibration diagnostics is of particular importance in rail transport safety systems because the signals received from vibration sensors installed on rolling stock, bridges, tunnels, and other infrastructure objects have great diagnostic information potential. Despite this, in practice, there are cases when the adequacy of the results of the vibration control and diagnostics task is not ensured. The reason is that the sampling step of the vibration signal does not change when the train speed changes. Given the need to change the sampling interval depending on the train speed, this article proposes an adaptive technology for vibration signal sampling that allows the building of intelligent systems of adaptive vibration control of malfunctions in rail transport.
EN
The dynamic behavior of a typical viscoelastic material in wide ranges of frequency and tem- perature is characterized. A four-parameter fractional derivative model was considered in the frequency domain along with the Arrhenius and WLF models, also for including tempera- ture as a source of variation. A Bayesian framework is adopted and inferences on parameters governing the model quantities of interest are based on samples from posterior distributions obtained by Monte Carlo Markov Chain (MCMC) methods. Posterior predictive checks were conducted to ensure the goodness-of-fit of the model. Based on the results we argue that the Bayesian framework allows more complete and suitable inference about dynamic properties of typical viscoelastic materials, as required for broad and sound vibration control actions.
EN
Considering the importance of gear systems as one of the important vibration and noise sources in power transmission systems, an active control for suppressing gear vibration is presented in this paper. A gear bearing model is developed and used to design an active control gear-bearing system. Two possible configurations of control system are designed based on active bearing and active gear-shaft torsional coupling to control and reduce the disturbance affecting system components. The controller for computing the actuation force is designed by using the H-infinity control approach. Simulation results indicate that the desired controller can efficiently be used for vibration control of gear bearing systems.
EN
In oil and gas industrial production and transportation plants, gas turbines are considered to be the major pieces of equipment exposed to several unstable phenomena presenting a serious danger to their proper operation and to their exploitation. The main objective of this work is to improve the competitiveness performance of his type of equipment by analyses and control of the dynamic behaviors and to develop a fault monitoring system for the equipment exposed and subject to certain eventual anomalies related to the main components, namely the shaft and the rotors. This study will allow the detection and localization of vibration phenomena in the studied gas turbine based on the input / output data.
EN
Nowadays, noise generated by devices is a serious issue in industry and in everyday life, because it may cause health damage to humans. In this research, a cubic rigid device casing built of double-panel thin steel walls is employed to reduce noise emitted from an enclosed noise source. Double-panel structure is used because of good sound insulation it provides. There exist three main groups of noise reduction methods, i.e. passive, semi-active and active. In this paper, a semi-active modification of double-panel structure is applied and examined. The bistable actuator (solenoid) mounted between incident and radiating plates changes its state due to applied constant voltage, causing the coupling of plates. Experimentally measured natural frequencies and modeshapes of the structure are compared to the simulation results. The influence of proposed modification on dynamical properties of the structure is analyzed and discussed.
EN
Majority of modern cars are equipped with standard suspension systems with hydraulic shock absorbers. They are reliable elements, but came to the limit of their possibilities to ensure reasonable level of vibration accelerations, when cars became lighter and diameters of the wheel rim and tires has big diameter. This paper provides possible solution for the modern car suspension systems with controlled damping and self-powering service and data transmission. Such dampers implements smart liquid and electrically realized damping force control. This paper focused on electrical properties of this type of shock absorbers. Provided experimental research use shock absorber – energy harvester of new design. All experiments performed on shock machine using produced by authors prototype of original design. Energy gaining performed using three similar prototypes with ferro-nanomagnetic liquid, permanent magnet core and ferromagnetic steel core. Obtained results provided in the graphical form as electric gain with open circuit and loaded by electric load.
PL
Większość nowoczesnych samochodów jest wyposażona w standardowe układy zawieszenia z hydraulicznymi amortyzatorami. Aktualnie stosowane amortyzatory są niezawodne, jednak nie umożliwiają dalszego rozwoju w odniesieniu do znacznych wartości przyśpieszeń drgań w lekkich samochodach o dużych średnicach felg i opon. Artykuł przedstawia nowe możliwości rozwiązań w nowoczesnych układach zawieszenia z kontrolowanym tłumieniem, autonomicznym zasilaniem oraz monitoringiem. Zaproponowane tłumiki zapewniają inteligentne, elektrycznie sterowaną siłę tłumienia. W pracy skupiono się na właściwościach elektrycznych zaproponowanych amortyzatorów cieczowych. Do badań eksperymentalnych wykorzystano opracowany przez autorów prototyp amortyzatora, a eksperymenty przeprowadzono na maszynie uderzeniowej. Pozyskiwanie energii z amortyzatora zrealizowano przy użyciu trzech podobnych prototypów z cieczą z nanocząstkami magnetycznymi na bazie żelaza, rdzeniem z magnesem trwałym i rdzeniem ze stali ferromagnetycznej. Uzyskane wyniki przedstawiono jako uzyskaną energię elektryczną zarówno w układzie z otwartym obwodem, jak i obciążeniem elektrycznym.
EN
The article presents a concept of using a controlled vibration eliminator to reduce vibrations generated during the turning process. The eliminator is embedded into the active holder supporting workpiece. A model of mechatronic system consists of a hydraulic actuator, a workpiece, and the machining process. A model of the system is used in the simulation of turning long, slender object. In the paper, the results of simulation for machining with and without vibration eliminator are presented. Based on the simulation, it was found that the designed system can limit vibration amplitude and increase the vibration stability in the turning process.
PL
W artykule przedstawiono koncepcję sterowania eliminatora do redukcji drgań powstających podczas procesu toczenia. Eliminator drgań został wbudowany w podtrzymkę przedmiotu obrabianego. Model systemu mechatronicznego uwzględnia hydrauliczny układ wykonawczy, przedmiot obrabiany oraz proces skrawania. Zasymulowano, a następnie porównano zachowanie się obiektu z oraz bez układu sterowania. Na podstawie symulacji stwierdzono, że zaprojektowany układ jest w stanie efektywnie ograniczyć amplitudę drgań oraz zwiększyć wibrostabilność procesu skrawania na tokarce.
EN
In this paper the problem of vibration control of a multi-member column subjected to the specific load is investigated. The vibration control is realized with the use of the piezoceramic element in the form of a rod that is connected to the host structure by means of the pins strengthened by rotational springs. The Hamilton’s principle is used during formulation of the boundary problem. The results of the numerical simulations are focused on the correction of the characteristic curves shape at a different radius of the loading head.
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.
PL
W artykule przedstawiono urządzenia wyposażenia i kontroli drgań mostów. Szerzej opisano masowe tłumiki drgań oraz urządzenia tłumienia wiskotycznego.
EN
Every bridge must be designed in a way that enables it to deform in ranges anticipated by the designer and disables to develop excessive forces that could cause the structure overload. Bridge bearings, expansion joints, tuned mass dampers and viscous damping devices are special products aimed at conforming to the above design requirements. The article presents the devices of bridge equipment and vibration control. Tuned mass dampers and viscous damping devices have been described in detail.
PL
W artykule rozpatrywane są drgania pojazdu wyposażonego w cztery półaktywne tłumiki. Siły tarcia powstające w tych tłumikach mają istotny wpływ na intensywność drgań pojazdu. Do oceny wpływu tłumienia drgań pojazdu wybrano funkcjonał kryterialny, zależący od wartości tych sił. Zagadnienie optymalizacji służy do wyznaczenia czterech wartości sił, dla których funkcjonał kryterialny osiąga minimum w każdej chwili. Na tej podstawie są wyznaczane sygnały do urządzeń sterujących działaniem półaktywnych tłumików. W pracy dokonano analizy przedstawionego zagadnienia w zakresie metody wyznaczania optymalnych wartości sił. Oprócz tego prezentowane są wyniki symulacji drgań pojazdu wyposażonego w półaktywne magnetoreologiczne tłumiki drgań. Zamieszczono także analizę wpływu postaci funkcjonału kryterialnego na efektywności redukcji drgań pojazdu.
EN
The article presents the vibrations of a vehicle equipped with four semi-active dampers. The forces generated in these dampers have a significant impact on the intensity of the vehicle's vibrations. To assess this influence, a criterial function was selected, depending on the value of these forces. The optimisation problem is used to determine the four values of forces for wich the criterial function reaches the minimum at any time. On this basis, signals are appointed to devices controlling the operation of semi-active dampers. In the work, we analyse the presented issues in the field of determining the optimal values of forces. In addition, the results of vibration simulation of a vehicle equipped with semi-active magneto-rheological vibration dampers are presented. There is also an analysis of the impact of the criterion functional form on the vehicle vibration reduction efficiency.
EN
The present work focuses on the study and analysis of vibrations generated by the electrical motor of a wiper system on its support bracket referring to an hatchback vehicle passenger car. In the electric motor of the wiper system there can be present an imbalance transmitting vibrations to the main body via the support bracket. In this paper, after a short resume of available synchronized switch shunt damping methods, a preliminary experimental evaluation of their potential performance on noise control of the wiper system is reported. After preliminary experimental measurements of dynamic vibration by the use of vibrometer laser both on the real hatchback car then in laboratory environment, a numerical model has been created to evaluate deformations of the support bracket for comparison with the experimental data. This work realizes the preliminary numerical/experimental characterization activity to set up a new application of a control system based on a semi-active technique, called Synchronized Switch Shunt Resonator (SSSR).
EN
A model and control strategy of a semi-active seat suspension system with a magneto-rheological (MR) damper, chiefly intended to protect construction machine operators from vibration acting in one of the horizontal directions, has been presented. The parameters of the model shown were determined experimentally as functions of the damper control current, for which a control algorithm imitating the operation of a sky-hook damper (a damper hanging from an inertial reference point) was developed. Afterwards, the model proposed was verified on a test stand with an electrohydraulic actuator and then the semi-active seat suspension system was experimentally tested with the participation of a human subject. Results of the work carried out have been presented in the form of power spectral densities of vibration accelerations and transfer functions of the suspension system. Based on a qualitative assessment of the test results obtained, the operation of the semi-active seat suspension system was found to be far more effective than that of a conventional system in the excitation frequency range under consideration. Noteworthy is the fact that the highest effectiveness of the system operation was achieved at the resonance frequency, corresponding to that of the passive system. This is confirmed by the tabulated values of vibration transfer coefficients and maximum relative displacements of the seat suspension system in the conventional passive version and in the semi-active version provided with an MR damper.
PL
W pracy zaprezentowano model oraz strategię sterowania semi-aktywnym układem zawieszeniem siedziska z tłumikiem magneto-reologicznym (MR), którego podstawowym zadaniem jest zapewnienie ochrony operatorów maszyn roboczych przed drganiami w jednym z poziomych kierunków oddziaływania. Parametry przedstawionego modelu wyznaczono eksperymentalnie w funkcji natężenia prądu sterującego pracą tłumika, dla którego opracowano algorytm sterowania naśladujący działanie tłumika zawieszonego w inercjalnym punkcie odniesienia (ang. sky-hook damper). Kolejno dokonano weryfikacji zaproponowanego modelu na stanowisku badawczym ze wzbudnikiem elektro-hydraulicznym oraz przeprowadzono badania eksperymentalne semi-aktywnego układu zawieszenia siedziska z udziałem człowieka. Wyniki zrealizowanych prac zaprezentowano w postaci gęstości widmowych mocy przyspieszenia drgań oraz funkcji przenoszenia układu zawieszenia. Na podstawie oceny jakościowej otrzymanych wyników badań stwierdzono, że działanie semi-aktywnego zawieszenia siedziska jest znacznie skuteczniejsze od układu konwencjonalnego w rozpatrywanym zakresie częstotliwości wymuszenia. Jednak największą skuteczność działania osiąga się w przypadku częstotliwości rezonansowej, odpowiadającej układowi pasywnemu. Potwierdzają to zestawione tabelarycznie wartości współczynników przenoszenia drgań i maksymalnych przemieszczeń względnych zawieszenia w przypadku konwencjonalnego układu pasywnego oraz układu semi-aktywnego z tłumikiem MR.
EN
The efficiency of vibration control in an automotive semi-active suspension system depends on the quality of information from sensors installed in the vehicle, including information about deflection of the suspension system. The control algorithm for vibration attenuation of the body takes into account its velocity as well as the relative velocity of the suspension. In this paper it is proposed to use the Linear Variable Differential Transformer (LVDT) unit to measure the suspension deflection and then to estimate its relative velocity. This approach is compared with a typical solution implemented in such applications, where the relative velocity is calculated by processing signals acquired from accelerometers placed on the body and on the chassis. The experiments performed for an experimental All-Terrain Vehicle (ATV) confirm that using LVDT units allows for improving ride comfort by better vibration attenuation of the body.
15
EN
In this paper, the application of tuned mass damper in improving the response of structures is considered. At first, three frames of 3, 9 and 20 stories are evaluated in which time history analysis is done according to El – Straw earthquake. The maximum reduction of among the three mentioned frames belongs to a 20-stories structure in which the rate of story displacement reduction is between 25 to 45%, and this indicates that by increasing the height of the structure, the performance of tuned mass damper improved. In the second part, the effect of semi-active tuned mass damper is studied on a 10-stories frame. Studies showed that using a tuned mass damper system with viscous damper with controller force decreases the average of maximum displacement of roof story down to 39.9 % and this amount of reduction is 22.8% for semi-active tuned mass damper. Finally, the performance of tuned Single and multiple mass Damper is evaluated on a 20-stories frame, and the results show that single and multiple dampers decrease structures ‘responses and the performance of tuned multiple dampers depends on the mass and frequency ratio and also concluded that the performance of tuned multiple mass dampers is reduced by transition to middle of the structure stories.
EN
The paper deals with the application of the continuous dynamic absorbers in vibration reduction problems in beams. The Euler-Bernoulli beam of variable cross-section is subjected to the concentrated and distributed harmonic excitation forces. The beam is equipped with a system of the continuous vibration absorbers. The problem of the forced vibration is solved employing the Galerkin’s method and Lagrange’s equations of the second kind. Performing time-Laplace transformation the amplitudes of displacement may be written in the frequency domain, similarly the time-averaged kinetic energy of any part of the beam. The results of some local and global vibration control optimization problems concerning the placement and parameters of the continuous vibration absorbers are presented.
EN
This study presents an analysis of a dynamic system consisting of a rigid hub and a cantilever flexible composite beam with an embedded active piezoelectric element. The system is excited by periodic oscillations of the hub angular speed. The macro fiber composite (MFC) active element is used to suppress beam vibrations. In the mathematical formulation of the problem the non-classical effects like material anisotropy and mode coupling due to an arbitrary stacking sequence of the laminate as well as the transverse shear deformations of the material are taken into account. Derived in previous research governing equations of the considered system are solved numerically by the finite difference method. Results of a numerical simulation are compared with experimental data including frequencies and mode shapes of natural vibrations and responses to unit step function excitations. Finally, the effectiveness of the piezoelectric actuator and the tested cubic velocity feedback control algorithm in order to suppress system vibrations is evaluated.
EN
In this paper an online adaptive continuous-time control algorithm will be studied in the vibration control problem. The examined algorithm is a Reinforcement Learning based scheme able to adapt to the changing system’s dynamics and providing control converging to the optimal control. Firstly, a brief description of the algorithm is provided. Then, the algorithm is studied by the numeric simulation. The controlled model is a simple conjugate oscillator with sudden change of its rigidity. The effectiveness of the adaptation of the algorithm is compared to the simulation results of controlling the same object by the traditional Linear Quadratic Regulator. Because of the lack of constraints for a system size or its linearity, this algorithm is suitable for optimal stabilization of more complex vibrating structures.
19
Content available remote Adaptive Stabilization of Partially Damaged Vibrating Structures
EN
In this paper an online adaptive continuous-time control algorithm will be studied in the vibration control problem. The examined algorithm is a Reinforcement Learning based scheme able to adapt to the changing system’s dynamics and providing control converging to the optimal control. Firstly, a brief description of the algorithm is provided. Then, the algorithm is studied by the numeric simulation. The controlled model is a simple conjugate oscillator with sudden change of its rigidity. The effectiveness of the adaptation of the algorithm is compared to the simulation results of controlling the same object by the traditional Linear Quadratic Regulator. Because of the lack of constraints for a system size or its linearity, this algorithm is suitable for optimal stabilization of more complex vibrating structures.
EN
The problem of active vibration suppression in a wide class of smart structures is addressed. The dynamical model of a structure may be perturbed by uncertain time-varying parameters and external disturbances. A novel adaptive-based control algorithm is presented here to satisfy robustness properties with respect to model uncertainties and environmental disturbances. Reflecting practical situations, the upper bound of perturbations is not required for controller design. The analytical stability of a closed-loop system is presented based on the Lyapunov stability theorem. Furthermore, numerical analysis is also provided to show the effectiveness of the proposed method.
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