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EN
Maintenance is a very important activity, which is necessary for the good operation of any technical system, even for the hydraulic drive systems. The predictive maintenance evaluates the state of technical performances of a system, by identifying the wear and thus avoiding the failures of the equipment. Using three methods of the predictive maintenance, namely infrared thermography, vibration analysis and oil analysis, the authors present their results of an experimental research on hydraulic pumps. The authors obtained thermograms, vibration spectra and diagrams of the oil contaminants which helped them indicate the proper or the malfunction of the studied pumps. Although they were only made on pumps, their investigations highlight the need of widely implementation of these modern and efficient methods in the industrial activities for the quick monitoring of the hydraulic machinery and equipment wear, before their failure occurs. Obviously, the goal is to have strong maintenance instruments in hydraulic drive systems diagnosis.
PL
Konserwacja to bardzo ważna czynność, niezbędna do prawidłowego działania każdego systemu technicznego, nawet hydraulicznych układów napędowych. Konserwacja predykcyjna ocenia stan wydajności technicznej systemu poprzez identyfikację zużycia i unikanie w ten sposób awarii urządzeń. Wykorzystując trzy nowoczesne metody konserwacji predykcyjnej, tj. termografię w podczerwieni, analizę drgań i analizę oleju, autorzy przedstawiają wyniki badań eksperymentalnych hydraulicznych pomp. Autorzy uzyskali termogramy, widma drgań i diagramy zanieczyszczeń olejowych, które pomogły wskazać prawidłową lub nieprawidłową pracę badanych pomp. Chociaż zostały wykonane tylko na pompach, ich badania podkreślają potrzebę szerokiego wdrażania tych nowoczesnych i efektywnych metod w działalności przemysłowej do szybkiego monitorowania zużycia maszyn i urządzeń hydraulicznych, zanim dojdzie do ich awarii. Oczywiście celem jest posiadanie mocnych narzędzi konserwacyjnych w diagnostyce hydraulicznych układów napędowych.
EN
Installations and the detection of their faults has become a major challenge. In order to develop a reliable approach for monitoring and diagnosis faults of these components, a test rig was mounted. In this article, a Multi Layer Perceptron (MLP) Artificial Neural Network (ANN) has been structured and optimized for online monitoring of induction motors. The input layer of our ANN used eight indicators calculated from the collected time signals and which represent the different states of the motor (Healthy, broken rotor bars, bearing fault and Misalignment) and the output layer used a codified matrix. However, based on L27 Taguchi design, the architecture for the hidden layers of our network is chosen, with the use of the LevenbergMarquardt learning algorithm. Garson's algorithm and connection weight approach showed that there's a great sensitivity of the crest factor, the kurtosis and the variance on the effectiveness of our diagnostic system. Consequently, the obtained results are capable of detecting faults in the induction motor under different operating conditions.
EN
Design considerations, material properties and dynamic properties of engineering applications, rotating components, turbine blades, helicopter blades, etc., have significante ffects on system efficiency. Structures made of functionally graded materials have recently begun to take place in such engineering applications, resulting from the development of composite material technology. In this study, vibration and buckling characteristics of axially functionally graded beams whose material properties change along the beam length is analyzed. Beam structural formulations and functionally graded material formulations are obtained for the Classical and the First Order Shear Deformation Theories. Finite element models are derived to carry out the vibratory and stability characteristic analyses. Effects of several parameters, i.e., rotational speed, hub radius, material properties, power law index parameter and boundary conditions are investigated and are displayed in several figures and tables. The calculated results are compared with the ones in open literature and very good agreement is observed.
EN
This article presents the vibration analysis of a turbocharger, whose compression wheel was manufactured using a high-precision additive manufacturing technology. Currently, there are advance studies around the world for the development of parts of innovative fluid-flow machines using additive manufacturing techniques. The experimental research was carried out under conditions of reduced flow temperatures. The tests and the analysis were performed on a wheel manufactured using a 3D printing technology and on a conventionally used aluminium wheel. Apart from an FFT analysis of the vibration signal during machine operation, a machine run-up test was conducted (up to a speed of 105,000 rpm). The results showed the positive impact of the use of a plastic wheel on the dynamics of the system at a certain speed range, which might contribute to the development of a new method to optimise the geometry of flow systems in small high-speed turbomachines. A modified automotive turbocharger was subjected to experiments on a test stand.
5
Content available remote Vibration analysis of functionally graded tapered rotor shaft system
EN
This investigation deals with the vibration analysis of a rotating tapered shaft in Functionally Graded Material (FGM). The dynamic system is modeled using the Timoshenko beam theory (FSDBT) with consideration of gyroscopic effect and rotary inertia. The equations of motion are expressed by the hierarchical finite element method based on bi-articulated boundary conditions. The material properties are continuously varied in the thickness direction of a hollow shaft according to the exponential law function (E-FGM). The presented model is validated by comparing the numerical results found with the available literature. Various analyses are carried out to determine the influence of taper angle and material distribution of the two extreme materials on the dynamic behavior of FGM conical rotors system.
EN
In this paper, the vibration analysis in terms of modal and harmonic responses are investigated for the power station structure of Kenyir Dam in Terengganu, Malaysia. Modal analysis is carried out to provide the dynamic characteristics of the power station which includes the natural frequencies and mode shapes. Meanwhile, the harmonic response analysis is performed by applying the force to the structure to obtain the Frequency Response Function (FRF) in certain range of frequencies. A real scale threedimensional (3D) model of the Kenyir Dam power station is constructed using Solid Works software and imported to ANSYS software for the Finite Element (FE) analysis. A proper boundary condition is taken into consideration to demonstrate the real behaviour of the power station structure. From the results, six most significant natural frequencies and mode shapes including the FRF in all three axes are selected. The highest natural frequency value occurred at 5.4 Hz with the maximum deflection of 0.90361 m in the z axis direction. This value is important in order to verify whether the structure can overcome the resonance phenomenon from the external disturbance forces in the future.
EN
The problem of propagation of vibration waves caused by the movement of rail vehicles in the ground is extremely important from the point of view of environmental protection against negative effects of dynamic impacts caused by rail transport. Therefore, there is a need to develop new methods for analyzing dynamic phenomena related to rail vehicle traffic. One of the methods that can be used to evaluate dynamic interactions is modeling using finite elements. The article presents a dynamic analysis of the track structure model and the impact of the application of its vibroisolation system on the level of ground vibration amplitude associated with the propagation of vibration waves from the track. The application of the finite element method allows for the analysis of the behavior of engineering structures in variable operating conditions dependent primarily on the speed of movement of vehicles on the track. Such analysis includes the use of a number of physical values that can be used to assess the impact of vibration on any engineering object. These values include, above all, acceleration at any measuring point on the measurement cross-section from the track to the engineering construction, e.g. a residential or industrial building as well as displacement or stress, which are dependent on the speed of the rail vehicle. Comparison of these values with generally available criteria and standards allows at the stage of designing the engineering structure for appropriate modifications to the substructure construction to limit the amplitude of the vibrations transmitted to the environment. These modifications consist mainly of the use of an appropriate vibroisolation system in the form of, for example, slabs or mats laid in the rail layer or pads underneath. Correct execution of the simulation requires careful preparation of the numerical model as well as a series of input data. The input data relate mainly to accurate material data concerning both engineering structures (bridges, viaducts, tunnels), rolling stock and soil parameters. Such data allow to prepare a spectrum of forces loading the modelled section of the track. This approach to the design process is particularly important due to the inability to modify the track after built it.
PL
Problem rozchodzenia się fal drganiowych powodowanych ruchem pojazdów szynowych w gruncie jest niezwykle istotny z punktu widzenia ochrony środowiska przed negatywnymi skutkami oddziaływaniami dynamicznych powodowanych przez transport szynowy. W związku z tym istnieje konieczność opracowania nowych metod analizy zjawisk dynamicznych związanych z ruchem pojazdów szynowych. Jedną z metod, którą można wykorzystać do oceny oddziaływań dynamicznych jest modelowanie z wykorzystaniem elementów skończonych. W artykule przedstawiono analizę dynamiczną modelu konstrukcji torowiska oraz wpływu zastosowania jego systemu wibroizolacji na poziom amplitudy drgań gruntu związanej z propagacją fal drganiowych od torowiska. Zastosowanie metody elementów skończonych pozwala na analizę zachowania się konstrukcji inżynierskich w zmiennych warunkach eksploatacyjnych zależnych przede wszystkim od prędkości ruchu pojazdów po torowisku. Analiza taka obejmuje użycie szeregu wartości fizycznych, które mogą służyć do oceny wpływu drgań na dowolny obiekt inżynierski. Do takich wielkości możemy zaliczyć przede wszystkim przyspieszenia w dowolnym punkcie pomiarowym na przekroju pomiarowym od torowiska do konstrukcji inżynierskiej np. budynku mieszkalnego czy przemysłowego jak również przemieszczenia lub naprężenia, które są zależne od prędkości pojazdu szynowego. Porównanie tych wartości z ogólnie dostępnymi kryteriami oraz standardami pozwala na etapie projektowania konstrukcji inżynierskiej na odpowiednie modyfikacje konstrukcji podtorzy celem ograniczenia wartości amplitudy drgań przekazywanych do środowiska. Modyfikacje te polegają głównie na zastosowaniu odpowiedniego układu wibroizolacji w postaci np. płyt lub mat układanych w warstwie torowiska lub podkładek podszynowych. Poprawne wykonanie symulacji wymaga dokładnego przygotowania modelu numerycznego jak i szeregu danych wejściowych. Dane wejściowe dotyczą przede wszystkim dokładnych danych materiałowych dotyczących zarówno konstrukcji inżynierskich (mosty, wiadukty, tunele), parametrów taboru jak i gruntu. Takie dane pozwalają przygotować widmo sił obciążających modelowany odcinek torowiska. Takie podejście do procesu projektowania jest szczególnie istotne ze względu na brak możliwości modyfikacji wybudowanego torowiska po zakończeniu prac budowlanych.
PL
Rozpatrywany jest model pojazdu wyposażony w sterowane tłumiki magneto-reologiczne (MR) oraz sterowane płaty aerodynamiczne. Analizowane są drgania pojazdu poruszającego się z dużą prędkością w trakcie przyspieszanie i hamowania. Celem tej analizy jest ustalenie wpływu sił powstających na płatach aerodynamicznych na drgania pojazdu oraz na zmiany nacisku kół na nawierzchnię drogi podczas przyspieszania i hamowania. W prezentowanej pracy przedstawione zostały wyniki badań numerycznych uzyskanych na podstawie opracowanego modelu pojazdu.
EN
We considered of a vehicle model equipped with controlled magneto-rheological (MR) dampers and controlled aerodynamic elements. The vibrations of the vehicle moving at high speed during acceleration and braking are analysed. The purpose of this analysis is to determine the effect of forces generated on aerodynamic elements on vehicle vibrations and changes in wheel pressure on the road surface during acceleration and braking. The presented work presents the results of numerical investigations obtained on the basis of the developed vehicle model.
9
Content available remote Simulation of bearing degradation by the use of the gamma stochastic process
EN
An effective predictive maintenance reposed on modeling, simulation, and on supervisory and prognostic techniques used to model the various phenomena. On this basis, and based on significant knowledge and parameters, we propose an approach based on stochastic processes that represent a mathematical structure for simulation, mainly the processes of continuous degradation and more particularly the Gamma process. Our work is devoted to the monitoring of the degradation process of the bearings at the level of a motor pump and makes it possible to evaluate the limiting operating time, as well as the evolution in time of the change of state. This methodology allows us to develop a mathematical model that describes the process of bearing degradation, thus providing a good prediction of failures and efficient maintenance planning for systems whose behavior is only partially predictable.
EN
A gravity damper is a one-way valve, employed for regulating the airflow rate in ducts, generally constituted by a series of rectangular panels (closure sections), connected to an articulated quadrilateral synchronizing the movements. If the device needs to process large masses of high speed air, as common in the case of energy conversion systems, disadvantageous dynamic effects can occur. In this study, vortexinduced vibration (VIV), occurring on a gravity damper for high values of the Reynolds number, is investigated. The analysis of this work couples numerical methods (Computational Fluid Dynamics with Large-Eddy Simulation turbulence model and Finite Element Method) to experiments: a full-scale accelerometric measurement campaign is actually performed at the wind tunnel facilities of the University of Perugia. VIVs are diagnosed and quantified through the experimental vibration analysis, which is interpreted through numerical simulations. The large amplitude of VIV is interpreted as due to a tendency towards lockin because of the approaching of the vortex shedding frequency to a natural vibration mode of the system. The integrated numerical and experimental framework finally inspires two different design solutions for mitigating the amplitude of VIV: these strategies are tested at the wind tunnel and they are indeed shown to be effective.
PL
Wraz ze wzrostem prędkości kolejowych pojazdów elektrycznych zwiększają się wymagania utrzymania sieci trakcyjnej w odpowiednim stanie technicznym. Ciągły monitoring i diagnostyka pozwalają wykrywać pogarszającą się jakość odbioru prądu z sieci jezdnej. Jedną z metod jest umieszczenie czujników przyspieszenia na przewodzie jezdnym. Analiza przebiegu przyspieszenia pozwala określić jakość współpracy sieci jezdnej z pantografem. Symulacja dynamiki takiego układu ułatwia dobór parametrów akcelerometrów. Wykorzystanie bezprzewodowej sieci sensorowej redukuje konieczność izolacji elektrycznej czujników od sieci trakcyjnej. W artykule omówiono projekt i realizację sieci sensorowej do rejestracji przyspieszeń przewodów sieci jezdnej. Zaprezentowano wstępne wyniki pomiarów laboratoryjnych.
EN
Together with increasing traction vehicle’s speed a need to maintain overhead contact lines in an appropriate technical condition constantly rises. Permanent monitoring and diagnostics is necessary to detect unfavorable phenomenon deteriorating current collecting quality e.g.: excessive wear of contact strips, incorrect vehicle’s pantograph force settings. One of the methods is to place acceleration sensor on the contact wire. Analysis of measured waveforms should allow quality estimation of cooperation the overhead contact line with the pantograph. Preliminary simulation of the dynamics of such a system facilitates selection of important accelerometer parameters. Wireless network selection as sensor network communication medium bypasses necessity for electric insulation between measurement system’s elements and overhead line. The design has to take into an account low power usage and renewable sources energy harvesting methods. The paper presents the results of simulation of dynamic pantograph cooperation with the overhead contact line. The design and realization of wireless sensor network to investigate the contact line acceleration are described. Preliminary laboratory measurement’s results are presented.
EN
The paper presents experimentally verified computational model of the collecting electrodes in ESP. Discretisation of the whole system is carried out by means of the modified rigid finite element method (RFEM). The aim of the simulations is to find correlation between stiffness of an anvil beam and vibration propagation, which guaranties the maximum amplitudes of vibrations and their proper distribution in the plates. The results of the conducted analyses may be useful to engineers and designers of ESP.
PL
W artykule przedstawiono eksperymentalnie zweryfikowany model dyskretny układu elektrod zbiorczych elektrofiltru suchego. Do modelowania układu zastosowano metodę sztywnych elementów skończonych (SES). Celem symulacji było poszukiwanie rozwiązań optymalnych sztywności drąga strzepującego ze względu na maksymalne amplitudy drgań oraz ich zrównoważony rozkład w układzie elektrod zbiorczych.
PL
Analiza drgań to bardzo często wykorzystywana metoda wykrywania usterek podzespołów mechanicznych maszyn elektrycznych. Wymaga ona posiadania pewnej wiedzy zarówno o samej metodzie, jak i o budowie maszyny.
EN
Cavitation is a common cause of failure in centrifugal pumps. Because of interaction of several mechanical parts and fluid, the vibration signal of a centrifugal pump is complicated. In this paper, the vibrations of a transparent-casing centrifugal pump are studied. Three states are studied experimentally: no cavitation, limited cavitation and developed cavitation. Each case was also confirmed by visually inspecting the cavitation bubbles. The vibrations of the pump was acquired by using an accelerometer that was attached to the casing. Discrete wavelet transform (DWT) analysis and empirical mode decomposition (EMD) are used to extract classification features from the acquired signals. Using these features, an artificial neural network (ANN) successfully diagnosed the cavitation condition of the pump. Finally, EEMD is also implemented. The results showed the success of EMD and DWT in cavitation diagnosis. The output of EEMD does not show significant change comparing to EMD.
EN
Fault diagnosis of an internal combustion engine is proposed herein by means of vibration analysis and a comparative analysis of normal operation and induced misfire scenarios. In order to validate previous works on misfire with pure gasoline, measurements also included tests performed with ethanol-gasoline fuel blends. According to results, changes in the fuel mix seem to have little impact on the performance and behaviour of the engine. And additionally, the particular frequency components that allowed differentiation between normal and faulty conditions were also present on all the fuel blends tested. Fast Fourier Transform was applied to obtain the frequency domain of the signal as a previous step to the subsequent identification process based on statistical characteristics extraction. A fuel blend classification method based on the analysis of the vibration signals of the engine was studied using envelope, Spike Energy and Peak Value techniques. Differentiation was possible with the extraction of the statistical features of the Peak Value spectrum of the longitudinal acceleration with a specific filter selection.
PL
Celem pracy jest określenie różnic w wynikach oceny komfortu uzyskiwanych różnymi metodami, oraz określenie zależności pomiędzy nimi. Zakres badań obejmował badanie drgań na siedziskach kierowców i załóg wybranych pojazdów i dokonanie analizy komfortu jazdy i określenie różnić w wynikach badań uzyskanych różnymi metodami i propozycja ich niwelacji. W pracy porównano metody badań eksperymentalnych pod kątem ich przydatności do oceny komfortu pojazdów specjalnych.
EN
The paper aims to determine differences between comfort assessment results achieved with the use of different test methods, and to define the interdependencies between them. The studies consisted in the following objectives: •vibration examination on the driver and crew seats of selected vehicles and the comfort of travel analysis, •determination of differences between examination results obtained with the use of various testing methods and proposal of these differences limitation. Experimental test methods were compared in the paper in the aspect of their suitability for special vehicles comfort evaluation. The paper has compared experimental test methods as far as their suitability for special vehicle comfort measurements is concerned.
PL
Wibrodiagnostyka maszyn wolnoobrotowych wymaga szczegółowej analizy tego trudnego tematu oraz wyboru odpowiedniej metody i oprzyrządowania. Autorzy przedstawiają problem na przykładzie badań przeprowadzonych w przemyśle wydobywczym. Ponadto nasuwa się spostrzeżenie, najprawdopodobniej wynikające ze współpracy mechaniczno-elektrycznej autorów, że metody dedykowane do analizy drgań np. łożysk nadają się również do analizy problemów w silnikach elektrycznych.
EN
Vibrodiagnostics of slow-speed machines requires a detailed analysis of this difficult topic and selection of appropriate methods and instrumentation. The authors present a problem for the example of research carried out in the mining industry. In addition begs the observation that the methods dedicated to vibration analysis, eg. bearings are suitable for analysis of the problems in electric motors.
EN
A static and dynamic analysis of Kirchhoff plates is presented in this paper. The proposed approach avoids Kirchhoff forces at the plate corners and equivalent shear forces at a plate boundary. Two unknown variables are considered at the boundary element node. The governing integral equations are derived using Betti’s theorem. The rectilinear and curved boundary element of the constant type are used. The non-singular formulation of the boundary (static analysis) and boundary-domain (free vibration analysis) integral equations with one and two collocation points associated with a single constant boundary element located at a plate edge are presented. Additionally, the classic three-node isoparametric curved boundary elements are introduced in static analysis according to the non-singular approach. Static fundamental solution and B`ezine technique are applied to the free vibration analysis. To establish the plate inertial forces, a plate domain is divided into triangular or annular sub-domains associated with one suitable collocation point.
EN
The paper represents an extension of a previous work where the problem of chatter in a rolling mill producing advanced high-strength steels (AHSS) was investigated by a combination of a linear lumped parameter model and the slab analysis. In this paper the authors show the detailed experimental study of the problem with a complete description of all the phases related to the vibrational investigation that lead to the solution of the problem. Furthermore, a different model based on the Orowan’s method together with a nonlinear model of the rolling mill is presented and simulations are performed.
20
Content available remote Wpływ modyfikacji ściernicy na stan niewyważenia wrzeciennika szlifierki SPD-30
PL
Obiektem badań była szlifierka do płaszczyzn, jest to szlifierka firmy Jotes, model SPD 30B. Celem pomiaru było sprawdzenie niewyważenia tarcz szlifierskich zamontowanych na wrzecionie obrabiarki. Ściernice na czynnej powierzchni zostały poddane modyfikacji. Wprowadzono zmiany ciągłości tej powierzchni aby można było łatwiej wprowadzać płyny chłodząco – smarujące w postaci mgły olejowej.
EN
The object of the research was planes grinder, this is a Jotes grinder, model SPD30B. The aim of the measure was to check the unbalance of grinding wheels mounted on the machine spindle. Grinding wheels on the active surface have been subjected to modifications. Changes were made continuity of the surface make it easier to introduce cooling fluids-lubricants in the form of mist.
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