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1
Content available remote Damping of vibration in an electric drive system with a long elastic coupling
EN
In the paper the uncomplicated structure of the active limiter of current reference for a BLDC motor control system is proposed. The limiter allows for uninterruptible operation of a speed controller due to the automatically adjusted rate of change of angular velocity reference depending on actual moment of inertia. The results of investigations, which confirm the effectiveness of the proposed structure, are presented.
PL
W artykule zaproponowano nieskomplikowaną strukturę aktywnego ogranicznika prądu zadanego w układzie regulacji prędkości kątowej silnika BLDC, która umożliwia bezprzerwowe działanie regulatora prędkości dzięki automatycznemu dostosowaniu szybkości narastania prędkości zadanej do dowolnego momentu bezwładności. Zaprezentowano wyniki badań, które potwierdzają skuteczność działania proponowanej struktury.
PL
Flender w monitorowaniu stanu skupia się przede wszystkim na bezpośrednim pomiarze drgań oraz analizie jego spektrum. Bardzo ważnym elementem badań jest także pomiar i analiza obciążenia momentem obrotowym bezpośrednio na wale przekładni lub sprzęgłach. Wraz z dodatkowymi informacjami na temat parametrów pracy przekładni, takich jak: ruch wału pływającego, temperatury czy ciśnienie, pomiary te pozwalają zdiagnozować stan przekładni w powiązaniu z czynnikami wpływającymi na jej pracę.
PL
W artykule przedstawiono drganiową metodę diagnozowania silników trakcyjnych wzbudzanych magnesami trwałymi, które są wykorzystywane m.in. w pojazdach elektrycznych. Metoda wykorzystuje właściwości maszyn elektrycznych z magnesami trwałymi, a mianowicie zjawisko indukowania się napięcia w uzwojeniu twornika pod wpływem drgań mechanicznych wirnika względem stojana. Przedstawiono genezę metody, podobieństwo do elektrodynamicznego czujnika drgań, wyniki obliczeń oraz badań laboratoryjnych mających na celu detekcję częstotliwości, które odpowiadają wibracjom, wymuszonych niewywagą wirnika.
EN
This article presents a vibration diagnostic method designed for permanent magnets (PM) traction motors. Those machines are commonly used in traction drives of electrical vehicles. Specific structural properties of machines excited by permanent magnets are used in this method – electromotive force (EMF) generated due to vibrations. This work presents: the method genesis, the similarity of permanent magnet machine and vibration sensor, results of calculations and laboratory tests.
EN
Using of laser vibrometers in vibration measurement systems brings additional benefits due to the lack of impact of the sensor on the tested measuring system. Recently, leading rolling bearing manufacturers are equipping their diagnostic measuring systems with non-contact sensors. Doppler laser vibrometers are used interchangeably for electrodynamic sensors. This paper attempts to assess the vibrometer in use for measuring vibration of rolling bearings in industrial conditions.
5
Content available Hybrid sandwich panels: a review
EN
A high specific stiffness, high specific strength, and tailoring the properties for specific application hale attracted the attention of the researchers to work in the field of laminated composites and Sandwich structures. Rapid use of these laminated composites and Sandwich structures necessitated the development of new theories that suitable for the bending, buckling and vibration analysis. Many articles were published on free vibration of beams, plates, shells laminated composites and sandwich structures. In this article, a review on free vibration analysis of shear deformable isotropic beams, plates, shells, laminated composites and sandwich structures based on various theories and the exact solution is presented. In addition to this, the literature on finite element modeling of beams, plates, shells laminated composites and sandwich structures based on classical and refined theories is also reviewed. The present article is an attempt to review the available literature, made in the past few decades on free flexural vibration response of Fiber Metal laminated Composites and Sandwich panels using different analytical models, numerical techniques, and experimental methods.
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
The article deals with atwo-mass above resonant oscillatory system of an eccentric-pendulum type vibrating table. Based on the model of a vibrating oscillatory system with three masses, the system of differential equations of motion of oscillating masses with five degrees of freedom is compiled using generalized Lagrange equations of the second kind. For given values of mechanical parameters of the oscillatory system and initial conditions, the autonomous system of differential equations of motion of oscillating masses is solved by the numerical Rosenbrock method. The results of analytical modelling are verified by experimental studies. The two-mass vibration system with eccentric-pendulum drive in resonant oscillation mode is characterized by an instantaneous start and stop of the drive without prolonged transient modes. Parasitic oscillations of the working body, as a body with distributed mass, are minimal at the frequency of forced oscillations.
EN
A dynamic advancement of the design of combustion engines generates a necessity of introduction of strategies of operation based on the information related to their technical condition. The paper analyzes problems related to vibration based diagnostics of valve clearance of a piston combustion engine, significant in terms of its efficiency and durability. Methods of classification have been proposed for the assessment of the valve clearance. Experiments have been performed and described that aimed at providing information necessary to develop and validate the proposed methods. In the performed investigations, the vibration signals were obtained from a triaxial accelerometer located in the engine cylinder head. A parameterization of the obtained vibration signal has been carried out for the engine operating under different engine loads, rotation speeds and valve clearance settings. The parameterization pertained to the specific features of the vibration signals, the derivative of the vibration signal as a function of time as well as the envelope of this derivative. In the first approach, the authors developed a classifier in the form of a set of binary trees that additionally allowed distinguishing the features significant in terms of the identification of adopted classes. For comparison, the authors also developed classifiers in the form of a neural network as well as a k-nearest neighbors algorithm using the Euclidean metric. Based on the performed investigations and analyses a method of valve clearance assessment has been proposed.
PL
Dynamiczny rozwój konstrukcji silników spalinowych generuje potrzebę wprowadzenia strategii eksploatacji jednostek napędowych, opartej na znajomości ich stanu technicznego. W artykule poddano analizie zagadnienia, związane z drganiową diagnostyką luzu zaworów tłokowego silnika spalinowego, istotnego ze względu na efektywność pracy silnika i jego trwałość. Zaproponowano wykorzystanie metod klasyfikacji do oceny poprawności luzu zaworowego. Przeprowadzono i opisano eksperymenty, które miały na celu dostarczenie informacji koniecznych do zbudowania i zweryfikowania zaproponowanych metod. W przeprowadzonych badaniach pozyskano sygnały drganiowe z trójosiowego czujnika przyspieszeń drgań zlokalizowanego na głowicy silnika. Dokonano parametryzacji uzyskanych przebiegów czasowych sygnału drganiowego dla silnika pracującego pod różnym obciążeniem, z różnymi prędkościami obrotowymi oraz z różnymi luzami zaworowymi. Parametryzacja dotyczyła zarówno cech sygnału przyspieszeń drgań, pochodnej przyspieszeń drgań względem czasu jak i obwiedni tej pochodnej. W pierwszym podejściu zbudowano klasyfikator w postaci zbioru drzew binarnych, który przy okazji pozwolił na wyodrębnienie istotnych, ze względu na przyjęte klasy, cech. Dla porównania zbudowano także klasyfikatory w postaci sieci neuronowej jak i algorytmu k – najbliższych sąsiadów z metryką euklidesową. Na podstawie przeprowadzonych badań i analiz zaproponowano metodę oceny luzu zaworowego.
EN
Entropy measurements are an accessible tool to perform irregularity and uncertainty measurements present in time series. Particularly in the area of signal processing, Multiscale Permutation Entropy (MPE) is presented as a characterization methodology capable of measuring randomness and non-linear dynamics present in non-stationary signals, such as mechanical vibrations. In this article, we present a robust methodology based on MPE for detection of Internal Combustion Engine (ICE) states. The MPE is combined with Principal Component Analysis (PCA) as a technique for visualization and feature selection and KNearest Neighbors (KNN) as a supervised classifier. The proposed methodology is validated by comparing accuracy and computation time with others presented in the literature. The results allow to appreciate a high effectiveness in the detection of failures in bearings (experiment 1) and ICE states (experiment 2) with a low computational consumption.
PL
The article presents findings from research on the effect of vibrations on the accuracy of measurement with an automatic precise digital leveller. A special research station was created to induce vibrations on a leveller and to measure vibration parameters that affect staff reading. It contains description of discovered relationship between the vibration parameters and the mean error of a single height difference measurement. The range of frequencies for which the measurement was possible was estimated. The reliability of the measured values obtained under specific vibration conditions was also analysed. The results of current research were compared with similar studies on analogue leveller Ni 002. The conclusions described in this paper can be helpful in engineering measurements under adverse conditions of ambient vibrations.
11
Content available remote Development of a new hexagonal honeycomb steel damper
EN
This paper presents a new metallic damper called hexagonal honeycomb steel damper (HHSD) for damage mitigation in structures subjected to earthquake excitations. The HHSD is composed of steel plates having several hexagonal and welded to the top and bottom anchor plates. The damper takes the advantages of hexagonal honeycomb geometry and steel material capability to dissipate seismic energy. The quasi-static cyclic test was performed experimentally and numerically on a series of specimens to evaluate the robustness of the HHSD. A three-dimensional finite element analysis of HHSD was carried out and verified with the experimental results. The results showed that the HHSD has low yield displacement, stable hysteretic behavior, a good range of ductility and high-energy dissipation capability. Additionally, the constitutive formulas of the damper are also derived based on the obtained results. Furthermore, it is found to have lightweight and inexpensive with ease of implementation as a potential alternative for new structures or seismic retrofitting of the existing structures.
EN
The concept of quasi-zero-stiffness (QZS) vibration isolator was proposed in recent decades to improve the low-frequency isolation performance without increasing the static displacement. This work is devoted to the concrete realization of a QZS isolator by utilizing transverse groove springs. Firstly, the QZS isolator is theoretically analyzed and some dynamical indices are analytically calculated. Then, the transverse groove springs are designed and the isolator prototype is assembled; the QZS feature of the prototype is basically fulfilled. Finally, the experiments are conducted by means of an electrodynamic shaker which generates sinusoidal base excitation for the isolator prototype; the experimental results clearly show the good isolation performance of the QZS isolator and meanwhile reflect some practical factors that should be noticed in actual applications.
13
Content available Multimodalne pomiary drgań struny
PL
W artykule zostały przedstawione badania drgań struny zrealizowane przy użyciu szybkich kamer wizyjnych, mikrofonu oraz akcelerometru. Obiektem badań były instrumenty muzyczne. Opisano zjawiska zachodzące w instrumencie podczas tworzenia się i wydobywania z niego dźwięku. Celem pracy było zbadanie różnic w wynikach otrzymanych poprzez pomiary wykonane z użyciem zróżnicowanych reprezentacji obrazowych i sygnałowych. Zaproponowano sposób pobudzania instrumentu, który pozwolił na wykonywane badań w sposób powtarzalny. Opisano metodologię wykonanych pomiarów oraz algorytm do analizy pomiarów wykonanych metodą optyczną, który umożliwił przetworzenie zarejestrowanego obrazu na sygnał foniczny. Na koniec zaprezentowano otrzymane wyniki z wszystkich modalności oraz wnioski z analiz.
EN
The article presents string vibration measurements carried out using fast vision cameras, a microphone and an accelerometer. Various types of acoustic guitars were selected for testing. The phenomena occurring in the instrument during the creation and extraction of sound from it were described. The aim of the study was to examine the differences in the results obtained through measurements made with different modalities and to determine which method gives the most accurate results. The measurements were carried out in an anechoic chamber, due to the need to maintain the closest possible ambient conditions during all measurements. A method of stimulating the instrument was proposed, which allowed for repeated tests. High-speed industrial cameras have enabled the recording of vibrations of selected points of the measured object. The work describes the methodology of measurements taken and the algorithm for analyzing measurements made using the optical method, which enabled the recorded image to be converted into an audio signal. The process of developing measurement data was discussed. Finally, the results obtained from all modalities and conclusions from the analyses were presented, and the possibilities of further experiments were proposed.
PL
W artykule poddano weryfikacji proponowaną w metodykę drganiowego badania degradacji konstrukcji budowlanych w zastosowaniu do oceny miar rozpływu energii drganiowej w segmentach murowych (ceglanych). Analizy teoretyczne i weryfikacja praktyczna badania wrażliwości informacyjnej proponowanych miar procesów drganiowych wskazują na szerokie możliwości ich zastosowań, w szczególności możliwe jest zastosowanie przedstawionej metodyki w zarządzaniu kontrolą jakości.
EN
The presented study subjected to the verification of dictated vibration methodology study of building structures degradation in the application to the assessment of vibration energy flow measurements in masonry (brick) segments. Theoretical analysis and practical verification of the information sensitivity testing of proposed measures of vibration processes indicate the wide possibilities of their applications, it is possible to apply the presented methodology in the quality control management.
PL
Przedstawiono wnioski wynikające z badań wibracyjnych i cieplnych hydrogeneratora-silnika umożliwiające ocenę jego stanu technicznego. Podano podstawowe przyczyny jego rekonstrukcji po ok. 40-letniej eksploatacji. Omówiono zakres proponowanej rekonstrukcji.
EN
The conclusions resulting from vibration and thermal tests of reverse hydro generator permitting the evaluation of its technical state are presented. Basic causes of its reconstruction after about 40 years of exploitation are presented. The scope of proposed reconstruction are discussed.
EN
One of the key methods for diagnosing the structural degradation of technical objects relies on observations of mechanical vibrations that accompany equipment operation and damage. Hardware and software advancements and the development mathematical methods for modelling and inference have increased the popularity of vibroacoustic diagnostics in mechanical systems. Displacement in the time domain of physical points in a vibrating object is the primary diagnostic symptom that undergoes further processing in the measurement system. At present, vibrations are usually registered with the use of accelerometers or optical sensors. Advanced tools for image recording, processing and analysis are deployed in quasi-realistic observations of motion that cannot be perceived by the human senses. This article discusses a method for visualizing vibrations based on deliberate deformation of the registered image through motion magnification. The presented approach is illustrated with selected examples.
EN
This paper presents the investigations of vibrations of a vehicle equipped with controlled magneto-rheological (MR) dampers and aerodynamic elements. A scaled sports vehicle model was developed to conduct this research. The tests were carried out with kinematic excitation resulting from road roughness and motion at a variable speed. During the airflow, the aerodynamic elements forces and moments on the test body. Vehicle vibrations are limited by the means of MR controlled dampers. The damping force is determined on the basis of an algorithm, where various strategies for determining forces in MR damper have been adopted. Two criteria were considered for assessing the effectiveness of the control algorithm - minimising vertical acceleration and changes in wheel normal reactions on road surface. This paper presents the results of those studies.
EN
This article specifies application of machine learning for the purpose of classifying wear level of multi-piston displacement pump. A diagnostic experiment that was carried out in order to acquire vibration signal matrices from selected locations within the pump body is described herein. Measured signals were subject to time and frequency analysis. Signal attributes related to time and frequency were grouped in a table in accordance with pump wear level. Subsequently, classification models for the pump wear level were developed through application of Matlab package. Assessment of their accuracy was carried out. A selected model was subject to confirmation. The article includes its summary.
19
Content available remote Drgania silników elektrycznych
PL
Drgania silników elektrycznych są jednym z częstszych objawów uszkodzeń, jakie mogą pojawić się w układach napędowych maszyn. Przyczyn takiego stanu może być wiele, dlatego tak ważne są umiejętne diagnozowanie i odpowiednie interpretowanie sygnałów drganiowych pozyskiwanych z obiektów przemysłowych.
EN
In this paper, the authors present an engineering method to identify the transmission paths of structure-borne sounds. The method is based on the use of a standardised impact sound source with an insulation case. The advantage of this approach is the possibility of obtaining repeatable results because the method allows the separation of structure-borne and airborne sounds; the latter do not interrupt the measurement even in the case of loose connections or elements of low acoustic insulation. The research on the verification of the method was performed on the façade of the Cracow Philharmonic building; the main structure-borne sound transmission paths were determined successfully. Knowledge of the sound transmission paths allows the subsequent design of efficient vibroacoustic protection.
PL
W artykule zaproponowano inżynierską metodę identyfikacji dróg transmisji dźwięków przenoszonych drogą materiałową przy użyciu wzorcowego źródła dźwięków uderzeniowych z odpowiednią obudową dźwiękoizolacyjną. Zaletą tego podejścia jest możliwość uzyskania powtarzalnych wyników dzięki odizolowaniu dźwięków uderzeniowych od powietrznych, które nie zakłócają pomiaru w razie występowania nieszczelności lub elementów o niskiej izolacyjności akustycznej. W celu weryfikacji metody przeprowadzono badania budynku Filharmonii Krakowskiej – wyznaczono główne drogi transmisji dźwięków przenoszonych drogą materiałową. Ich znajomość jest niezbędna do projektowania skutecznej ochrony dźwiękoizolacyjnej.
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